sum. Hybrids don't exist. Not yet, anyway.
Humankind took a turn when, while diving in places they shouldn't, humans found a specimen that rests exactly between human and animal, uncanny, wrong to human eyes.
They named it merfolk.
And the next step was, of course, capture, explore, study, disturb - not exactly in that order, but you get the message.
You are kindly pressured into accepting a role to study a single subject that has been captured and caged, but not only that, you are now also responsible for teaching the subject your mother language, and you're doing it by sharing a house with it with no possibility to leave until they decide you're done.
tags. interspecies, merfolk, greatwhiteshark!sukuna, hybrid au, sharkuna, p in v, oral f!receiving, mound nuzzling, scenting, possessiveness, blood, biting, apex predator sukuna, double cocks, different cocks, dp, anal sex, exhaustion, multiple orgasms, dubious consent, period sex, orca!toji, octopus!suguru, eel!mimiko&nanako, possessiveness, lore so much lore, parasite, based on the dolphin x scientist experiment in the sixties, have fun reading it.
art: @kcokaine
🦈 MEGALODON MASTERLIST:
ETHOGRAM ENTRY I — Week 1–8: Acclimation, Refusal, Observation
ETHOGRAM ENTRY II — Month 6–14: Speech Emergence, Trust as Method
ETHOGRAM ENTRY III — Year 2: Handling, Trade Behaviors, Mutual Reliance
ETHOGRAM ENTRY IV — Year 3: Terminal Sampling and Summer Storms
ETHOGRAM ENTRY V — Year 3: The Cove and the Wonders beyond the Veil
ETHOGRAM ENTRY VI — Year 3: Shark Week and Resolutions
ETHOGRAM ENTRY VII — ??????: Merfolklore, Saltblood and the Becoming.
ETHOGRAM ENTRY VIII — Epilogue: Selkies, Guidance and Home.
ETHOGRAM ENTRY IX — Attachment #1: Prey
ETHOGRAM ENTRY X — Attachment #2: Decision
ETHOGRAM ENTRY XI — Log File #001 - Orcas
ETHOGRAM ENTRY XII — Log File #002 - Mating
ETHOGRAM ENTRY XIII — Log File #003 - Rupture
🪸 Appendages references for all of you who would like to know what was he using to impale you 🫦
🐚 MEGALODON FAQ.
🦈 Some FANARTS and yapping about him and worldbuilding because I have the best readers in all the internet, that's not a question.
↪︎ oh-my-sanity + oh-my-sanity | jin-jamm-desu | nevergreen24 | moonsquid49 | whendesdaythursday | readerinthedark05 | the House
He is half out of the cave before you have fully caught your breath.
It is the first thing that matters once the panic leaves enough room in your head for anything else. Not the scrape along your shoulder, not the way your chest still works too hard from fear, not the lingering image of black-and-white bodies cutting the water into smaller and smaller pieces around you.
Sukuna is already moving toward the mouth of the cave, and the shape of him says more than his face ever needs to.
He is not thinking. He is deciding.
There is a difference, and you know it now.
Thinking is when he goes quiet and strange, when his eyes narrow and stay half-lidded and the claws of one hand drag absent, shallow lines into rock like he is tracing routes only he can see.
Thinking is patient, ugly, controlled.
Thinking is what he does before he chooses the best angle to ambush, the best word to bait, the right time to lunge.
This is not that.
This is rage stripped down to intent. It lives in the set of his shoulders, in the low line of his spine, in the way his tail cuts once through the water and makes the whole cave seem to tighten around him. It lives in the black widening of his pupils until the crimson ring is just a thin red insult around something far older and meaner.
He has heard Toji, he has seen the scrape on you, and now the whole of him is turning in one direction.
Out.
Your first instinct is stupidly human. It has not left you, no matter what saltblood did, no matter what shape your lower half took. You reach.
You throw yourself after him and catch his arm with both hands.
Your seal body is still adjusting to urgency in tight spaces. On land you used to step into someone’s path, plant your feet, use your weight.
Now you pull yourself over the smooth stone shelf with your palms and your core when you’re going out of water, flippers dragging and catching faintly on rock.
When you’re in, you lunge, you swim towards him on a little desperate movement and by the time you get to him you are breathless from the remnants of fear. It does not matter. You get your hands around his biceps anyway, arms locking hard, cheek almost brushing the line of his shoulder.
“Sukuna.”
He does not stop.
He does not even look at you at first. He drags you a fraction with him because your grip means less to his momentum than a loop of kelp would, and the only reason you do not end up hauled half out into the open water clinging like a remora is because he finally pauses out of irritation. His body goes taut with the effort of not shrugging you off violently.
“You will let go.”
“No.”
The word leaves your mouth too quickly, sharpened by the image of the reef fissure and Toji’s face filling the entrance while the pod sealed every direction that meant survival. Your fingers tighten, nails pressing against wet skin and the black lines that band his arm. He is warm despite the cold of the cave water. You can feel muscle shifting under your grip, a dense, living threat.
He turns his head then, slow enough to make it deliberate. His eyes flick down to where you cling to him, then up to your face. The expression is not soft. It is annoyed first, then edged with something darker because he can still smell the leftover fear on you. It offends him. It always has.
“They chased you.”
“Yes.”
“They tried to eat you.”
“Yes.”
His upper lip lifts in a sneer, a start of a snarl.
“Then move.”
You shake your head, hard. Your hair floats around you with the movement, soon settling again, heavier than the water’s density.
“No.”
Something in his face changes at your repetition. Not surprise. He knows you can be stubborn. He knows because he spent years watching you refuse good sense whenever good sense felt too close to surrender. He knows because he watched you argue with the board through clenched teeth and then throw your whole life into the sea because they wanted his brain on a tray. He knows because you keep asking questions even when the answers make your life worse.
He still hates the timing.
One clawed hand comes up, not quickly, and settles against the side of your face. The touch is rough only because he is rough, not because he is trying to hurt you. His thumb presses at your jaw, pushing your face up slightly so you have to hold his gaze.
“They will not chase you again when I am done.”
That certainty would have thrilled you once. It would have sounded like safety with teeth. Now it curdles in your gut because the pod did not move like random aggression or stupid dominance. They moved like a mechanism built out of bodies that trusted each other’s angles. They moved the way you used to watch coordinated hunters move on grainy footage in marine behavior seminars, pausing frames and drawing arrows with a laser pointer while professors called it intelligent predation like intelligence made it less terrifying.
And Sukuna — Sukuna is Sukuna. Too large, too violent, too quick, too certain. He is not easy prey for anything. But you have seen what orcas do to great whites.
Not myths. Not stories. Data. Evidence. Torn livers.
Bodies rolled and stunned and harried until even mass and muscle mean less than numbers and strategy. You have spent too many years around water to romanticize apex predators as invincible.
You know what orcas do to sharks.
You know what a pod can do to one.
You slide one hand from his arm to his chest and push. It is like trying to move a cliff face with your palm, and you feel stupid the second you do it. He does not shift by even a fraction. The broad plane of his sternum remains where it is, warm and immovable under your hand. Your seal half bunches awkwardly under you, flippers angled wrong against the stone because you do not have the leverage you want, because moments like this are when you miss your legs with a flash of real irritation. Legs could wrap. Legs could brace. Legs could box him in, if not physically then emotionally, turn your body into argument.
Now all you can do is press your palm to his chest like it means something.
It means something to you, if not to physics.
“I don’t want you going.”
His nostrils flare.
“That is foolish.”
“Maybe.” Your throat is still sore from fear and from the long swim home, but you force each word clean. “You going alone to pick a fight with an orca pod is also foolish.”
His mouth curls. Not amusement. Offense.
“I would win.”
The answer is immediate, effortless.
It lands in the water between you like a fact rather than a boast, and the worst part is that a part of you believes him. You’ve seen him hunt. You’ve seen him move in ways your eyes barely catch up to. You’ve seen him take violence with the same matter-of-fact ease he uses to eat.
You’ve watched Toji bleed because Sukuna decided one boundary had been crossed and one fin was an acceptable lesson.
He is not bluffing. He really does believe he could tear through them.
And he probably could do major damage. He is too big, too fast, too brutal in close range. One-on-one, maybe even one-on-two, you can imagine him winning by simply refusing the rules. You can imagine him taking bodies apart in ways that leave the water full of panic.
But pods are not duels.
Your mind flashes again to Maki below you, Mai above, Naoya cutting the path before you even fully chose it. Toji hanging back just enough to let the machine work. Not chaos. Not individuals. Structure.
You take a breath that comes in thin and tastes faintly metallic with leftover panic.
“I know what orcas do,” you say.
He clicks his teeth, impatient.
“You know what humans say.”
“No.” The word comes out stronger than you expect, sharpened by the old anger of classrooms and notes and all the useless expertise that still lives in you. “I know what I studied. I know what I’ve seen.”
His gaze shifts slightly, enough to say continue or stop. You continue because stopping means he leaves.
“You think I don’t know how impressive you are?” you ask, and there is a strange sting behind the words because the answer matters more than it should. “I’ve seen you hunt. I’ve seen you move. I know you’re stronger than most things that should exist. But I also know what orca pods do to great whites. I’ve seen it in footage, in necropsy photos, in papers. I know how they herd. I know how they wear a shark down and keep wearing it down until size stops mattering.”
His jaw tightens, but he still does not leave. That’s enough to keep talking.
“You’d hurt them,” you say, quieter now because the image itself is getting under your skin. “You’d probably kill some of them. I know that. But I’m not afraid you won’t do damage. I’m afraid you’ll do enough damage for it to become a bloodbath, and then what. Then you’re torn open in ten places because you wanted to prove a point.”
His upper lip curls, offended all over again by the idea that his death could be folded into a tactical argument.
“You worry like prey.”
“And you answer everything like violence is the only language that counts.”
“It is the only language they used with you.”
You close your eyes for one beat. He’s not wrong. They hunted you. They boxed you in. They were going to eat you because you were alone and soft and looked enough like what they already take from the water to slot neatly into their instincts.
Still.
You open your eyes and stare at him until he has to acknowledge the stubbornness in your face.
“You do not get to die over this.”
His pupils narrow slightly.
“You do not decide that.”
“Then I’ll make it very inconvenient.”
That gets something close to amusement out of him, dark and brief. It disappears just as fast. He can smell you’re serious. He can feel the tremor under your skin that says this isn’t only about logic. Fear has wrapped itself around something warmer and uglier and more personal.
You slide lower, because your upper body is tiring from the way you have to hold yourself even underwater, and shift your grip so your arms go around his forearm instead. You hug his arm with all the leverage you can manage, cheek pressing briefly to wet skin and tattoo lines. It is pathetic as restraint. It is also the most honest thing you can think to do.
He glances down at you and snorts, a harsh little breath through his nose.
There’s that damned urge again, the one that makes you miss your legs like missing a weapon. If you still had them you could throw one over his lap, wrap around his waist, make yourself into a living obstacle.
He chuckles then.
It’s not nice. It’s that low, dark rumble out of his chest that always sounds like laughter sharpened on bone. The vibration travels through his arm into your cheek where you’re pressed to him.
The sound infuriates you because it means he finds this at least a little entertaining.
You lift your head just as his face lowers, and for a half second your body expects teeth on skin, a light punitive bite to make you let go. He does that sometimes when you annoy him past patience — nips your shoulder, catches the soft edge of your upper arm, not hard enough to break but enough to warn.
His teeth brush your ear instead.
Not a bite. A nibble. A deliberate drag of serrated edges so careful it makes your whole body go rigid for a completely different reason. Heat crawls up your neck instantly. You hiss his name and he pulls back just enough to show the shape of his mouth curving at one corner.
“You’re impossible,” you mutter, because if you don’t say something your own body will betray you harder than it already has.
“And you’re clinging,” he answers. “One of us is at least honest.”
You flush hotter, which helps nothing.
“I’m serious.”
He clicks his teeth softly.
“So am I.”
You take a breath, gather yourself, and lower your voice because if he won’t stop for reason maybe he’ll stop for something closer to the inside of you.
“I don’t want you picking senseless fights.”
The chuckle dies. His expression flattens into something more dangerous.
“It is not senseless.”
“Sukuna—”
“Toji tried to eat you.” Each word comes out distinct and ugly, as if he has to keep them from turning into a snarl. “His pod chased you. They touched what is mine.”
There it is. Not safety. Not justice. Possession sharpened into motive. It should make you angry. Right now it only makes your chest ache with a mess of things you refuse to unpack while he is trying to go start a war.
You tighten your hold on his arm.
“You know what I am now.”
His eyes narrow.
“Yes.”
“A seal.”
He says nothing.
“And seals are…” You grimace because the phrasing is humiliating, but maybe humiliation is useful if it delays him. “They’re exactly what orcas love to eat. Prime prey. Fat. Soft. Easy to handle if they get you alone. Gourmet shit, basically.”
One of his brows draws down. He looks insulted on your behalf and annoyed by the information at once.
You keep going because it’s working just enough that he hasn’t ripped free yet.
“That doesn’t make it okay,” you say. “It doesn’t make what happened less terrifying. It just means it isn’t personal to them the way it is to you.”
His mouth turns into a hard line. He clicks his teeth once, then again, a habit you’re starting to recognize as him turning a thought over so hard he could bite through it. You feel the motion travel through his arm where you hold him.
“They should know better.”
You almost laugh because what a sentence. What a perfectly ridiculous, arrogant, Sukuna sentence to say about predators following their nature.
“Why. Because I’m with you.”
“Yes.”
He says it like it’s obvious. Like affiliation should rewrite instinct on sight.
You close your eyes for one second and open them again.
“That’s not how pods work.”
“It should.”
“That’s not an argument.”
“It is mine.”
You almost tell him he is impossible again. Instead you shift your grip and hug his arm harder, forehead brushing the edge of his bicep. Your voice comes out softer, because logic has gotten you only so far and what’s left is the truth.
“I was scared,” you say. “And I’m still scared. But right now I’m more scared of you going after them alone.”
That lands, finally.
You feel it more than see it at first — a tiny stilling under your hands, a pause in the restless anger of his muscles. Sukuna does not go gentle. He does not go soft. But he does pay attention when you stop trying to win and just say what hurts.
He exhales through his nose, a long, irritated breath that stirs the hair at your temple.
“You worry too much.”
“Yes.”
“Foolishly.”
“Yes.”
His gaze drags over your face, lingers at your throat where your pulse still jumps too fast, then moves away toward the cave mouth again. The water outside is darker now, evening settling through the kelp and rock. The cave feels smaller because all his intent is still pointed outward, but it no longer feels quite so imminent.
You risk a little more.
“You know my major,” you say quietly. “You know that’s how I ended up there. Marine biology. Predator behavior. Migration. Diet patterns. The stupid irony is not lost on me, by the way.”
He glances down at you, expression unreadable.
“I spent years studying this,” you continue. “And I’ve seen too many cases where a lone shark ends up dead because a pod decided to make an example of it, or decided a liver was worth the effort, or just decided the water belonged to them that day. They don’t fight like sharks. They don’t fight like you. They grind. They coordinate. They feint. They keep going until the stronger thing is too hurt to matter.”
He listens. That’s already more than you feared you’d get.
“You would win some part of it,” you repeat. “I know you would. But I don’t care about some part. I care about you coming back.”
The words are out before you can polish them into something safer. They hang there, raw and embarrassingly direct.
Sukuna’s eyes flick to your face with a sharpness that makes your stomach dip. For a second he says nothing at all. Then one corner of his mouth moves, not quite a smile, not quite mockery.
Something lower and stranger.
He lowers his head until his temple brushes yours for one brief, almost absent moment. If you were still human in the old way, maybe you’d call it tenderness. As it is, it feels more like acknowledgment through contact.
“You make it difficult to leave,” he says.
“You’re welcome.”
That actually gets the smallest hint of a real huff out of him, amused despite himself. It fades quickly.
You are not done. You know better than to stop at the first crack.
“If you care so much,” you murmur, “then don’t go.”
He rolls his shoulder under your grip as if testing whether you’ll hold harder. You do.
He could break free. He chooses not to.
The silence stretches just long enough that your mind tries to fill it with disaster again.
Then he says, flat and irritated,
“I won’t go if you care this much.”
You blink up at him. You expect to hear the trick in it. Some loophole. Some phrasing that means I won’t go now, I’ll go in ten minutes when you’re asleep. Sukuna is entirely capable of that kind of technical honesty.
“Really,” you ask, because trust is still not something you hand out without checking the blade first.
His lip lifts.
“Do you want me to lie more prettily.”
“No.”
“Then stop asking foolish questions.”
Relief hits you so fast it almost makes you sag. You don’t, because you don’t entirely trust this yet, but your grip loosens by a fraction without your permission.
He notices. Of course he notices.
You clear your throat.
“You could still try talking to Toji.”
That finally gets a real laugh out of him, low and brief and wholly disbelieving. It shudders through his chest and arm and into your hands where you hold him.
“Talking,” he repeats, as if the word itself is ridiculous.
“You know what I mean.”
“I do not.” He looks genuinely offended by the concept. “I hunt with him. He hunts with me. Prey dies. We eat. Then we leave. There is no talking.”
You squint at him.
“There is definitely talking. I heard all of you.”
“That is not talking. That is deciding where the meat goes.”
You almost smile despite yourself because the simplicity is so violently him that it becomes absurd.
“You could still tell him,” you say. “Who I am.”
His expression flattens again.
“That I’m me,” you press on. “That scientist. That human he met with you before.”
“I know who you are.”
“Sukuna.”
His pupils narrow slightly. He is listening even while he pretends he isn’t.
“Maybe if he knows I’m not random prey,” you say, “it changes something. Maybe not everything. I know enough about orcas not to assume they’ll suddenly become polite because you asked. They’re opportunistic and clever and manipulative as hell. Toji especially. I know what kind he is. He learned human speech by using it against people. That alone should tell you enough.”
His jaw shifts once, annoyed all over again that you know facts that don’t flatter him into immediate violence.
“But maybe,” you continue, “if he knows I’m attached to you, he doesn’t keep testing. Or maybe he does, but at least he’s doing it with information.”
Sukuna goes silent. Really silent this time. Not absent. Processing.
You take the chance to let go of his arm and resettle yourself more comfortably against him before your shoulders decide to give out. The moment your hold changes, one of his hands comes down to your hips as if it was always going there.
You’ve noticed that lately. More and more often. The way he touches the softness of your seal half when he’s thinking, the slight press of claws into the plush skin over your hips and flanks.
It started as assessment when you were changing — checking temperature, checking tone, checking whether your body held warmth right. It turned into something else by degrees so small you only noticed after it had already become habit.
He kneads.
There isn’t a prettier word for it. His broad hand spreads over your hip, claws just dimpling the skin enough to leave faint impressions, and then his fingers flex in an almost absent rhythm.
Press. Ease. Press. Ease.
Testing and enjoying at the same time. The first time he did it you thought he was checking for swelling. The tenth time you realized he was doing it when he was annoyed or restless or just had you close enough to reach.
It reminds you horribly of a cat. A giant, homicidal, sea-born cat with too many teeth and absolutely no shame.
It also feels good.
It feels like a massage if the masseuse might eat people and never admits to affection.
You try not to smile at the thought. He’d take it personally.
His claws press slightly deeper, not enough to hurt, just enough that you feel the drag through the dense softness of your new body. He looks away while doing it, like if he doesn’t meet your eyes the action doesn’t count as indulgence.
You think it is cute.
You would rather drown again than say that out loud.
“You’re fidgeting,” you murmur instead.
He pinches one side of your hip in response. Not hard. A warning.
“You’re still talking.”
“You like when I talk.”
“No.”
You huff out the smallest laugh, because there is no point arguing the obvious. His hand keeps working at your hip, slow, methodical, his claws sliding lightly under the plush skin and releasing. The kneading eases some of the leftover tension in your muscles from the chase. It also makes heat settle low in you in a way that’s almost unfair given the conversation you’re having.
He pulls you closer with the same hand after a moment, a smooth drag across stone and water until you’re pressed along his side. His warmth seeps into you. You can feel the heavy line of his torso, the scarred roughness where human skin gives way to shark body beneath the water.
He doesn’t look at you while he does it. He just arranges you where he wants you and continues his absentminded, possessive handling like your softness is a thing he’s discovered and keeps needing to confirm.
You let him. Because it feels good. Because after fear your body wants contact it recognizes. Because his heat is familiar in a way the rest of the sea still isn’t.
He speaks eventually, voice low.
“You should let go. I should get food.”
You don’t move.
“For us or for your pride.”
His hand pauses for half a beat, then resumes kneading as if the interruption never happened.
“For food.”
You tilt your head to look at him.
“And maybe if Toji happens to be there, you’ll accidentally find a way to snarl at him.”
He says nothing.
That silence tells you everything.
You stare at the side of his face. He’s looking out toward the cave mouth, expression flat, jaw set. The hand at your hip has not stopped moving.
Press. Ease. Press. Ease.
“You were going to,” you say, because now that you know the shape of his silences it’s impossible not to call them out.
Still nothing.
You exhale through your nose.
“You’re really impossible.”
He pinches the edge of one flipper with two claws, just enough to make you twitch.
“You’re alive.”
You want to stay angry at that. You can’t. Not fully. Not when the relief of him staying is still spread through you like warmth.
So you do the only thing left. You lean in and nibble his shoulder.
His skin there is rougher than a human’s, salt and old scar and muscle under your teeth. You don’t bite hard. Just enough to annoy.
Sukuna’s head turns slightly.
“Careful.”
“You said I can bite now.”
“You can.” His voice lowers. “Not me.”
“You’re very authoritarian for someone who claims he doesn’t do talking.”
He huffs, amused despite himself.
You let your forehead rest briefly against his shoulder and feel the slow rise and fall of his breathing. Outside, currents move through the kelp. Inside, the cave holds a quiet that feels earned and temporary.
“I’m serious, Sukuna,” you say after a moment, softer. “Please don’t go pick fights for my sake.”
His hand stills at your hip. Then the kneading resumes, slower.
“It is not only for your sake.”
That makes you pull back enough to look at him again.
“No?”
His eyes flick to yours at last, dark and unreadable except for the thin red ring around the pupils.
“Toji touched what is mine,” he says. “That offends me whether you’re frightened or not.”
There is no use arguing the mine right now. The word has become one of his facts, the same way currents and hunger and territory are facts. You know what he means by it. You also know the word doesn’t erase your own will. You are here because you keep choosing to be, and he knows that even if he dresses it up as ownership.
Still.
You trace one finger lightly over the black banding near his wrist and choose your next words carefully.
“If you tell him who I am,” you say, “and if he has any interest in not making this into a blood feud with you, maybe that’s enough.”
Sukuna’s mouth curves slightly, humorless this time.
“He likes blood feuds.”
“I know.”
“He likes provoking.”
“I know.”
“He likes human meat.”
“I know,” you repeat, and you hate the way your body remembers the words.
Toji himself learned enough human language to lure people.
You remember that too vividly now. How many coastal disappearances got filed as accidents. How many strange stories men laughed off because it was easier than admitting something in the water could sound like your own kind and still want to eat you.
Sukuna studies your face while you’re thinking that, and the hand on your hip changes rhythm again — less kneading now, more a slow drag of claws just against the skin, a grounding touch.
You take a breath.
“That’s why I’m not saying trust him. I’m saying information matters.”
His eyes narrow.
“You sound like Suguru.”
“That is one of the worst things you’ve ever said to me.”
He actually shows teeth in brief amusement at that.
“Good.”
You huff.
He falls quiet again, but it’s not the same dangerous silence as before. It’s less pointed outward, more inward. Calculation at last.
Thinking instead of deciding.
You stay tucked against him while he does it, because you know better than to break contact when he’s choosing restraint instead of action. Your body gradually unwinds from fight or flight. The ache in your shoulders from clinging eases. Your flippers relax against stone and water. His heat seeps deeper. The cave’s dimness settles around both of you like a held breath.
He starts kneading again in earnest. Not absentmindedly this time. Deliberately. One hand braced at your waist, the other working at the plush softness over your lower half with a slow, almost methodical pressure that makes it obvious he enjoys the sensation.
You’ve caught him doing this enough times that you can read the pattern now.
He does it when he’s restless. He does it when he’s thinking too much and needs part of himself occupied. He does it when he wants you close and won’t say that plain.
He doesn’t name it. He doesn’t even seem to think about naming it. He just does it because he wants to and because your body is there.
You let your eyes drift half shut for a second and say, because the truth is easier when you’re tired,
“That feels nice.”
His hand pauses for the smallest instant.
Then his claws press in again, just a little deeper, and his voice comes out lower than before.
“I know.”
Of course that’s his answer. Not good. Not I’m glad. Just the blunt fact that he can feel your body’s responses and understands them on instinct. It’s irritating. It’s also somehow reassuring in the exact way you don’t want to admit.
You slide one hand up to the side of his neck and rest it there, not restraining him anymore, just touching. The muscle under your palm is dense and warm. You can feel the echo of tension still coiled there, waiting.
“You’re still angry,” you murmur.
“Yes.”
“At me?”
“No.”
“At Toji.”
“Yes.”
“At the whole pod.”
He glances down at you.
“Yes.”
“At the fact that I went alone.”
His mouth flattens.
“Yes.”
You sigh quietly.
“That one’s fair.”
His thumb digs into the softness at your hip in what might be approval or simple continuation of the same restless need to feel you under his hand.
The silence stretches long enough to become companionable. Outside the cave, fish move in the dark. Somewhere farther out a distant pressure change travels through the water, too far away to be immediate danger.
Sukuna hears it and ignores it — his attention is on you now, split between watching the entrance and making sure you stay where he put you.
You think, because your brain refuses not to, about how ridiculous your life has become.
Years ago you were in a lab, staying late over data sets and coffee gone cold, writing grant applications and pretending men who interrupted you in meetings mattered less than they did.
Then a secret project, a cliff island, a tank house cut in half by glass, a great white merfolk with too many teeth and too much attention.
Then escape. Fever. Saltblood. Becoming. A cave under the sea. Orcas that know how to speak enough human to use it as bait.
And here you are, pressed to Sukuna’s side trying to keep him from starting a fight because you’re afraid for his life.
The thought almost makes you laugh again.
Instead you say,
“I still think you should tell him.”
Sukuna exhales through his nose.
“You won’t stop.”
“No.”
He looks faintly aggrieved by your consistency.
“You would pester the sea itself if it annoyed you enough,” he mutters.
“You say that like you aren’t currently proving the same thing.”
His mouth twitches once, irritation and acknowledgment braided together.
Then, at last.
“If I see him.”
It’s not much. It’s a concession. A thread. You take it immediately.
“You’ll tell him.”
“I’ll make sure he understands.”
“That’s not the same—”
“It is to me.”
You close your eyes for half a second and reopen them. Fine. That is probably as close as you’re getting to diplomacy from him. If he intends to deliver the information in the form of a threat wrapped around Toji’s throat, that is still technically communication.
“I’ll take it,” you say.
“You should.”
You tilt your head and look up at him.
“You’re unbearably smug for someone who was about to do something very stupid.”
He leans down just enough that his mouth is close to yours, not a kiss, just pressure and threat and warmth all mixed together.
“And you’re unbearably interfering for someone who almost got eaten.”
You don’t pull away.
“Maybe I learned from the best.”
That finally makes him show enough teeth to count as a real grin.
Then, because he can never let a moment stay too soft for too long, he pinches your flipper again. You jerk and glare. He looks pleased with himself.
“You’re awful.”
“You’re soft.”
“You always say that like it’s an insult.”
“It is a statement.” His hand returns to your hip and resumes the slow kneading. “You make that difficult too.”
Heat rises under your skin again, less from embarrassment this time and more from the simple intimacy of being touched this way while your bodies settle after fear. There is something almost domestic about it, if domestic can include claws and territorial threats and discussions of orca predation.
You wonder, not for the first time, what this would look like to anyone else. Then you decide you don’t care.
He shifts after a while, pulling you more fully against him so your upper body rests along the slant of his chest and his arm bands your waist. The position is half protective, half ownership, entirely Sukuna.
“You should rest,” he says.
“I’m not tired.”
“You’re lying.”
You are, a little.
The crash after fear is setting in. Your limbs feel heavier. Your thoughts keep snagging on the image of the pod circling. The safety of the cave is making the adrenaline wear off in waves.
Still, you don’t want to stop talking yet. Talking means he stays here and doesn’t vanish into the dark with murder in his head.
So you ask,
“Did you really think you’d win.”
He looks almost offended by the question.
“Yes.”
“Against all of them.”
“Yes.”
“Even with coordination.”
His hand flexes at your hip.
“You assume I would let them keep theirs.”
You stare at him for a long second and then laugh despite yourself, because of course that would be his angle. Not weathering the formation. Breaking it. Cutting through the pattern until the pod stopped behaving like one thing and started behaving like individuals again.
It would probably work for at least some of it.
That doesn’t make it safe.
You lift your hand to his face, thumb brushing the edge of one marking near his cheek.
“You’re terrifying.”
He doesn’t deny it.
“You’re alive.”
Again, that answer.
Again, the way he uses it as if it explains everything he does and every choice he almost made.
Maybe, for him, it does.
You let your hand stay where it is. He tolerates it with the kind of stillness that means he likes it more than he’ll admit. The water around the cave mouth darkens fully into night now, the outside world reduced to drifting silhouettes and occasional flashes of bioluminescence in the far currents.
The cave is warm by comparison now, warm because he is, warm because the stone holds what little heat the day left behind, warm because you’re both still breathing and no one is bleeding in the dark.
You realize then that your grip on his arm loosened long ago. You are no longer holding him in place.
He is just… staying.
The thought softens something in you that was braced for a fight.
So, softer too, you say,
“Thank you.”
He doesn’t ask for what. He knows. For staying. For listening. For not turning your fear into another body count.
He looks away toward the cave entrance, jaw shifting once.
“You care too much,” he mutters.
You smile faintly.
“You’ve said that before.”
“And I was right before too.”
“Probably.”
His hand at your hip presses in with one last slow knead, claws just grazing the plush skin. Then he stills it, palm broad and warm over you, holding more than touching now.
After a long silence, he says,
“Tomorrow I’ll hunt near the outer current.”
You tense slightly despite yourself.
He feels it at once and glances down at you.
“Near. Not with them. If I see Toji, I’ll tell him.”
You study his face, measuring the truth of the promise. He meets your gaze without blinking.
No loophole. No trick. Not a surrender, but not a lie either.
You nod slowly.
“Okay.”
“Okay,” he echoes, as if the word is strange in his mouth and somehow yours to say first.
Your body finally lets fatigue claim more ground. You settle further into him, head heavy against his shoulder, the steady rise and fall of his breathing doing something your own nervous system can’t quite do alone yet.
He curls a little more around you, instinctive, keeping the shape of his body between yours and the cave mouth. The movement is protective in that brutish way he has, one that would look like dominance to anyone watching and feels like shelter from where you are.
You let your eyes close.
Just before sleep starts to drag at you, he speaks again, voice low enough that it almost gets lost in the water.
“If I get hungry enough,” he says, “I’ll eat you instead. Then you won’t have to worry about dolphins’ goth cousins.”
Your eyes open just enough to glare at him.
“Orcas,” you mumble, too tired to be properly offended. “Not dolphins.”
His mouth rumbles against your hair in that dark almost-laugh again.
“Same ugly family.”
“You’re not funny.”
“And you’re still here.”
The words settle in you warm and heavy, not because they’re sweet — he doesn’t do regular sweet — but because they’re true.
You’re still here. He’s still here.
The pod is somewhere beyond the reef and the dark and the currents, and for tonight he’s not going to them.
For tonight, that’s enough.
You let sleep pull you under with his arm around your waist, his hand spread possessively over the softness of your seal half, claws barely dimpling the skin as if even in rest some part of him has to keep confirming you’re real.
ETHOGRAM ENTRY III — Year 2: Handling, Trade Behaviors, Mutual Reliance
The call comes on a Tuesday that looks like every other day in here — pale light, slow tide, the same mechanical breath of pumps and filters pretending to be ocean.
The phone on the wall never rings gently — It snaps the quiet in half like it has always resented it.
You dry your hands on a dish towel that’s already damp and pick it up on the third ring, because letting it go longer feels like defiance you can’t afford.
“Dr. —” you begin, and the name in your mouth tastes like paperwork.
A man answers.
Not the one you usually report to, not the polite voice that pretends to care about your well-being.
This one is clipped, tired, important in the way men get when they’ve decided they don’t owe you softness.
“We need your quarterly,” he says. “In full.”
The words make something in your shoulder blades tighten.
“I sent the last batch three weeks ago.”
“Partial.”
“It wasn’t partial. It was measured.”
A pause, the kind that punishes you for speaking back.
In the background you hear other voices, pages turning, a chair dragged across the floor.
He’s in an office that smells like stale coffee and authority, and you’re in a house built to keep two living beings contained.
“Your methodology has changed,” he says.
“It’s improved.” you correct, before you can stop yourself.
On the other side of the glass wall, Sukuna is surfaced at the shore ledge, upper body out, the water sliding off him in thin sheets.
He’s not pretending to sleep, He’s watching you with that lazy stillness that always makes you feel like you’re the specimen with a clipboard, not him.
“You’ve grown... personally involved,” the man continues. He doesn’t say it like a concern, he says it like a diagnosis.
You stare at the phone cord. Twist it once around your finger. Untwist.
“He responds better to sustained interaction. He learns faster when there’s continuity, when it isn’t a rotation of handlers.”
“He’s not a child,” the man says flatly. “He’s an asset.”
The word makes your stomach roll.
You keep your voice even anyway, because your anger will only feed them.
“He’s a person. An individual.”
A second of silence, then a faint laugh — short, unimpressed.
“Don’t start with that. You’re overly emotional. It’s been noted.”
You feel heat rise up your neck.
Not shame.
Rage held under your tongue like a bitter tablet.
“If you want results,” you say, carefully, “then you want trust. You want language. You want him calm enough to cooperate. And yes, he is calmer with me.”
“So you admit attachment.”
“I admit efficacy.”
He ignores that. Of course he does.
“What we want is quantifiable progress. We want demonstration, recorded on tape. We want comprehension tests. We want—” papers shuffle, “—comparative behavioral mapping. Social tendencies. Dominance signals.”
Your eyes flick to Sukuna again.
His mouth curves, almost imperceptible.
He knows what they’re asking.
Maybe not the words, but the tone — people outside deciding what to take from him next.
“I can provide social observations,” you say slowly. “Within the limits of a single subject in isolation.”
“You’re creative,” the man answers, which is not a compliment. “Make it work.”
And then, like he’s tossing you a bone, he adds,
“We’ll be sending a team in a few weeks to evaluate next steps.”
Your fingers tighten on the receiver.
“Next steps?”
“You’ll be informed.” he says.
“You’ve kept me in the dark for a year. I need to know what happens when—”
“You need to do your job,” he interrupts. “That’s all.”
Your jaw locks.
“You will have your quarterly. But I want it in writing that you won’t introduce invasive procedures without my presence.”
Another pause, longer.
When he answers, his voice is colder.
“You’re not in a position to bargain.”
“I’m the only reason he hasn’t eaten anyone else you’ve thrown at him.” you say, and you hate that you have to play their language to be heard.
In the glass reflection, Sukuna’s eyes narrow, amused at the venom in your voice.
As if he’s pleased you’re finally biting back.
The man exhales, irritated.
“Send your report. We’ll talk later.”
The line clicks dead.
You stay with the phone against your ear for a second too long, listening to the empty hum, as if it might turn into an answer if you wait hard enough.
When you finally hang up, the house feels smaller.
You don’t move right away, you stand there in the kitchen, hand still hovering near the receiver, and let the anger settle into your ribcage.
Behind the glass, Sukuna shifts.
The motion is economical — one hand flexing, claws scraping faintly against sand, the shark half of him adjusting in the water with a slow sweep of tail. He doesn’t come closer yet.
He doesn’t need to.
His attention fills the space without effort.
“Emotional,” he says, and the word isn’t quite clean, but it’s good enough to make your spine stiffen.
You turn your head toward him.
“You heard that.”
A faint tilt of his chin. Not yes, not no. He likes making you say things out loud.
“Don’t.” you warn, because you can already hear the shape of his mockery forming.
His mouth pulls into something sharp.
“They talk. You take. You shake.”
“I don’t—”
“You do.” His gaze drops to your hand, the one you’ve curled into a fist without noticing. “Your blood go fast.”
You swallow.
You hate that he knows you this way, that your body betrays you around him, that he reads you like you read a chart.
“It’s nothing.” you lie.
His top lip lifts slightly, a sneer, baring the tips of teeth.
“Liar.”
You let out a breath that feels more like surrender than air.
“They’re sending a team. They still won’t tell me what happens after.”
Sukuna’s expression doesn’t change, but the water around him seems to tighten — less idle drift, more gathered presence.
“After.” he repeats, tasting the word.
“After the research.” you explain, because he forces you to be clear. “After they decide they have what they want.”
“What they want.” he says, and there’s contempt in it, thick and steady.
You pick up your notebook from the counter just to have something in your hands.
“More. Always more.”
His eyes stay on you.
“And you?”
You hesitate.
“What do you want?” he clarifies, voice lower, slower, like he’s choosing words that will stick.
The question lands wrong.
Too intimate for a kitchen.
Too honest for a place built on lies.
You look down at the notebook.
“I want you alive.”
A beat.
Then he huffs, soft and derisive.
“Stupid.”
“You asked.”
He shifts closer to the glass, torso rising a little more out of the water. The tattoos across his chest — those unmistakable black marks — look darker when they’re wet, like ink that never dries.
“You want ocean.” he says, like he’s naming one of your habits. “You want leave. But you stay.”
“I don’t have a choice.”
His gaze narrows.
“You always have choice.”
“Not here.”
You could leave, he’s right. Then someone else would take you place, someone that would use violent methods to extract what they want from him.
It’s easier to pretend you have no choice and abdicate of your freedom in order to keep him as safe as you can.
He doesn’t argue directly.
He never does when the truth is ugly, he simply watches you until the silence makes you keep talking.
“I sent them enough to keep them complacent,” you admit, voice quieter. “Not enough to make them... excited.”
He understands that kind of strategy.
You see it in the way his eyes brighten slightly, like a predator recognizing another predator’s patience.
“You keep,” he says. “For you.”
You swallow.
“Yes.”
A slow smile, all teeth and no comfort.
“Good.”
The approval shouldn’t warm you.
It does anyway, shamefully, like sunlight through the glass ceiling.
You turn away before he can see too much of your face.
“I’m going to work.”
“You always work,” he says, a complaint disguised as observation.
“It keeps me sane.”
He makes a low sound, unimpressed.
“Talk.”
You shut your eyes briefly, then open them and pick up your pen.
Fine. You’ll talk.
You’ll feed him words because it keeps him engaged, because it keeps him from sinking into the kind of silence that feels like coiling.
You settle at the edge of the shore ledge — close enough that your feet can dip into the shallows, far enough that you can still stand if you need to.
The sand is damp under your thighs.
The water kisses your ankles in slow, shallow pulses.
Sukuna drifts closer, head level with yours now, eyes tracking your mouth.
“Tell me,” you say, as if you’re directing an interview instead of negotiating with something that could break you. “You said before... great whites aren’t always solitary.”
His gaze flicks, amused at how you dress curiosity up as research.
“Humans,” he begins, and the word comes out with its usual blend of disdain and grudging respect. “You like stories. Lone hunter. Big teeth. No friends.”
You roll your eyes.
“You’re not exactly friendly.”
“Exactly.” He leans his forearms on the sand, shoulders broad, claws half-sunk. “Not friendly. Still... together.”
You angle the notebook on your knee.
“When?”
“Food,” he says simply, then expands when you keep waiting. “Place with seals. Place with whales. Place with blood in water. Many come.”
The way he says many is strange — flat, as if numbers don’t impress him, but memory does.
“Like a feeding ground.” you murmur, writing.
He watches your pen move.
“Looks like party,” he says, tone dry. “Not party. Just... same thing. Everyone want.”
You glance up.
“Do you... recognize individuals?”
His lips curl as if the question is naive.
“Sometimes.”
“Sometimes,” you echo. “So there’s variation.”
He taps a claw against the sand once, impatient.
“Some stay near others. Some go alone. Some... young, travel. Two. Three.”
Your pen stills.
“You traveled with another.”
His gaze shifts away, to the far end of the tank.
For a moment he looks older than he ever lets himself appear — less amused, more... remembering.
“Juvenile,” he says. The word is clumsy, but he forces it out. “Not big yet. Teeth new. Hungry.” His eyes cut back to you. “Always hungry.”
There’s a flicker of humor in that last part, like he’s mocking his own past.
“Who?” you ask softly, surprising yourself with the gentleness.
Sukuna’s mouth tightens.
“Dead.”
The answer is immediate, brutal, a door slammed shut.
But his claw drags a short line in the sand as he speaks, absent, a physical outlet for something he won’t name.
You nod, and you don’t press.
You’ve learned which questions make him bite.
“Dominance,” you try instead, shifting to safer ground. “When many gather... what happens?”
Now he perks up, because this is territory he enjoys — hierarchy, control, the language of bodies.
He leans closer.
“Big first.”
“Size determines rank.”
“Mostly.” He shows teeth briefly. “Sometimes not size. Sometimes... mean.”
You snort softly.
“You.”
He gives you a look like you’ve finally said something intelligent.
“When together,” he continues, “they talk with body. Nudge. Slam. Bite small.”
His claw taps the outside of your calf, right where your leg meets water, a light, almost teasing touch.
“Like this.”
You jerk slightly anyway, reflex more than fear, and his eyes gleam.
“You do it to me.” you accuse.
“I teach.” he corrects, smug.
“You torment.”
“Same.”
Your mouth twitches.
“And cooperative hunting?” you ask, because you’ve read the papers, because you want to compare his lived knowledge to the sanitized language of journals.
His gaze sharpens.
“Yes.”
“How?”
He settles his weight more firmly on the shore, arms braced, posture like he’s about to demonstrate.
“One go near prey,” he says. “Make prey move. Panic. Other wait. Ambush.”
“A decoy.” you murmur.
He makes a sound that could be agreement.
“Simple. But work.”
You scribble notes, then glance up.
“Have you done it?”
He looks at you, and the answer is in his face before his mouth moves.
“Yes,” he says, and his voice has that quiet satisfaction in it, like he’s describing a craft.
“With another great white?” you press, unable to help it.
He pauses, then shrugs one shoulder.
“With many. With orca sometimes.” He bares teeth, expression turning sour. “Orca think they king. Annoying.”
You blink.
“You hunted with orcas.”
“Sometimes same food,” he says, dismissive. “Not friends.”
“So it’s opportunistic coordination.”
He watches you write and gives a small, approving hum when you use a word he likes — big words, human words that make you feel clever.
He likes them the way he likes watching you squirm — as proof he can pull something out of you.
You spend an hour like that, trading information for proximity, your stress slowly draining into the page.
Then the sun shifts behind clouds and the ceiling glass goes gray, and you realize you’ve been sitting with your legs in the water without flinching, without checking his hands every second.
You realize you trust him.
The thought lands like a bruise.
Sukuna’s gaze lifts to your face as if he’s been waiting for you to notice.
“You calm now.” he observes.
You don’t deny it.
“Talking helps.”
He taps his claw lightly against your ankle again — less dominance now, more insistence that you stay present.
“You talk,” he says. “I listen. Trade.”
“What do you want?” you ask, even though you already know it’s never simple.
His pupils widen slightly, dark swallowing more of the red ring.
He leans in just enough that you feel the warmth of him before he touches you.
“Touch.” he says.
Your breath slows. You keep your voice steady.
“What kind of touch?”
His mouth curves, and for once it isn’t purely cruel.
It’s hungry, but controlled.
“Study,” he says, mocking your own language. “Like you. I study you.”
You swallow and look down at your notebook, because meeting his eyes when he says things like that makes you feel too exposed.
“Fine,” you say. “But after you let me do a full oral exam.”
A pause.
He blinks, slow.
“Mouth.”
“Yes.”
His grin sharpens.
“You want my teeth.”
“You have seventy-some teeth. Constant replacement. The patterning is unique in hybrids. I need to see.”
“Need,” he repeats, amused. “Sure.”
You glare at him, and he laughs without sound — just a breathy shake in his chest.
“You won’t bite me.”
A slow blink.
“I will not bite,” he repeats carefully, like he’s carving the promise into stone.
You exhale.
“Okay.”
The fact that you’re negotiating terms with him like a contract makes you want to laugh and cry at once.
You set your notebook aside on dry sand and rinse your hands in the shallow water, scrubbing your nails like ritual.
You don’t want fish oil on your skin. You don’t want blood. You don’t want anything that might make him decide you taste like food.
Sukuna watches your preparation with that patient attention he reserves for things he respects.
When you finally shift closer, kneeling at the waterline, he rises further out of the water and settles onto the shore ledge.
The shark half of him stays submerged, tail sweeping once, then still. His upper body is all muscle and wet skin and ink-black markings, and the membrane between his fingers flexes when he plants his hands in the sand on either side of you.
He’s close enough that you can smell him properly — the clean salt, the faint metallic edge that never fully leaves him, the animal warmth under it all.
“You nervous.” he says, tone almost conversational.
“I’m careful.” you correct.
“Same thing.”
You roll your eyes, but your hands hover for a heartbeat.
He notices. He always notices.
Sukuna leans forward slightly, closing the distance without touching you, and tilts his head.
“Look.” he says, as if granting permission.
You swallow and lift your hands to his face, fingers braced along his jaw the way you would with a large dog — except this isn’t a dog, and the power under your palms is different, ancient and coiled.
His skin is rougher near the edges of his mouth, smoother along his cheekbones.
You trace the line of one tattoo that cuts near his eye and feel the raised texture where ink sits under skin.
“Open.” you say.
His mouth curves, and he opens it slowly.
The first thing that hits you is the sheer architecture — rows that look too sharp to belong to anything that breathes air, enamel meant for tearing.
His gums are darker than yours.
His tongue is broad, the surface textured in a way that speaks of water and friction and prey that struggles.
You force yourself not to react like a startled animal.
You’re here to keep your mind from dissolving.
You slide two fingers in, careful, staying near the front, touching one tooth at a time.
They’re cold at first — water-cooled — then warm where his breath hits them.
You trace the serrated edge of one and feel the precision of it.
Sukuna stays still, eyes half-lidded, watching your face more than your hands.
“You like.” he murmurs.
“It’s... incredible.” you admit, and it’s the most honest you’ve sounded all day.
He makes a small, pleased hum.
You shift your fingers slightly, pressing gently at the gumline, noting the angle, the spacing, the way the teeth sit like interlocking blades.
“You get quiet.” he murmurs around your fingers, the sound vibrating faintly against your skin.
“I’m working,” you say, lowly.
“You look like prey when you work.” he answers.
Your heart trips. Your fingers still.
Sukuna’s eyes gleam.
You pull your hands out a fraction and glare.
“I am not prey.”
His mouth curves.
“You are in my mouth.”
You hate the heat that rises in your face.
You hate that he can provoke it with a sentence.
You shove your fingers back in with more firmness than necessary.
“Hold still.”
Sukuna hums, amused, and lets you continue.
Your thumb slides, accidentally, against the corner of his mouth.
He closes his jaw a fraction — enough to trap your fingers without pressure.
You freeze.
“Still okay?” he asks, and the words come out with that exact, cruel softness you’ve come to recognize — the one that makes your consent feel like both power and humiliation.
You swallow and force your voice to stay steady.
“Yes. Still okay.”
His grin deepens, satisfied with the tremor he hears anyway.
He releases you and opens wider, as if rewarding compliance.
You keep going, refusing to let him make you shy. You count. You map. You murmur notes out loud, partly for memory, partly to keep your mind anchored away from how close he is, how his forearms bracket your hips, how the warmth of him seeps into your skin.
When you’re done, you don’t pull away right away.
Your hands remain on his face, fingertips tracing the line of a tattoo that isn’t ink — at least not originally. You’ve learned enough from his skin to suspect the markings are more than decoration, something old and ritualistic that humans copied poorly when they started trying to categorize his kind.
You touch the edge near his cheekbone.
“These weren’t done by humans.”
“No.” he says.
“By who?”
He blinks.
“Mine.”
You tilt your head.
“Your people tattoo each other.”
He snorts softly.
“You always want rules. It is not rules. It is claim. It is story. It is warning.”
You trace the line with your thumb.
“And yours says what?”
Sukuna’s eyes narrow, and for a moment he looks almost pleased to be asked.
Then he answers, quietly,
“It says do not come close.”
Your throat tightens.
You don’t say what you’re thinking — that you came close anyway, that now you live close enough to count his breaths.
Instead, you move your hands down, to the membrane between his fingers, lifting one webbed hand and stretching it gently to see how the skin pulls.
He watches you with that same focused patience, as if letting you learn him is its own kind of indulgence.
“You are gentle.” he says suddenly.
You snort.
“Don’t get used to it.”
His mouth curves.
“Too late.”
The trade shifts, like it always does.
“My turn.” he says.
You blink.
“To examine my dentition?”
He narrows his eyes in a way that is all mockery and intent.
“To examine my scientist.”
You feel heat climb your throat, rapid and ridiculous, as if you have not spent two years sharing space with him, swimming within arm’s reach of his teeth, listening to him talk about how he and his kind tear seals apart.
You start to slide back, to put distance between your body and his, but his hands are already moving.
Those big, webbed hands leave the shore and come to your waist with practiced ease.
He does not grab sharply. He does not bruise. He presses, thumbs digging into the curve above your hip bones, fingers wrapping around to the small of your back.
“Trade.” he reminds you. “You learn me, I learn you.”
“We have different definitions of research ethics.” you manage.
“Yours are boring.” he says.
He doesn’t push you down, he leans in.
His torso crowds closer, his weight a steady, undeniable presence between your knees.
Your balance goes, and you end up leaning back on your hands in the sand, looking up at him from entirely too close.
Sukuna’s gaze drops to your throat, then to your chest, then back to your face.
He catalogues you with the same unhurried precision you used on his teeth.
“You soft everywhere.” he says, almost contemplative. “Even where you think you not.”
“You have said that before.” you mutter.
“Keeps being true.”
His hands shift. One slides down to your thigh, fingers pressing into the muscle, testing resistance. The other trails up your side, skimming ribs through fabric, pausing where your breath hitches.
He notes every reaction.
You have no illusions about what this is.
He is not gentle because he has become domesticated.
He is gentle because he has full control and this is the option he is choosing in this moment.
It would be easier if that did not make something inside you loosen.
He leans down until his mouth is level with your shoulder.
His breath skims your skin, hot in contrast with the cool air of the House.
His nose pushes aside the collar of your shirt, baring the curve where neck meets shoulder.
“Warning marks.” he murmurs, eyes flicking to the faint white lines there from old accidents, old clumsy dives, a childhood of climbing rocks and ignoring caution. “Your kind scars small.”
“So do yours.” you say quietly, thinking of the thick pale lines crisscrossing his upper chest, the missing piece of dorsal fin, the dent near his flank that could only be human harpoon work.
He makes a sound that might be agreement.
Then his teeth graze the skin above your collarbone.
Not a bite, a hint.
Enough pressure to prick awareness, to let your body know that the potential is there.
Your breath stutters.
Your hand finds his forearm without thinking, fingers wrapping around inked skin.
He feels solid under your palm, wet warmth radiating up your arm.
“Sukuna,” you say, not in protest, not exactly, but more as an anchor point.
He pulls back a fraction, crimson eyes watching your face.
“You trust me.” he says.
Not a question.
A statement he is checking for weaknesses.
You exhale slowly.
“More than is wise.”
He smiles, slow and feral and satisfied.
“Good.”
It becomes a pattern.
You study him — he studies you.
You take meticulous notes on the minor ways his pigmentation shifts over time, on the way his gill slits flare when he exerts himself, on how his eyes respond to light changes in the tank.
He lets you trace the raised edges of old wounds, lets you press fingers to places where the human portion of him transitions into shark, feeling the subtle change in skin texture.
In return, his hands learn your body in the same steady, exploratory way.
He pokes at the soft concavity above your knee. He squeezes the muscle of your calf as if testing how much strength is hidden there. He slides his thumb along the inside of your elbow and watches the shiver pass through you with genuine curiosity.
Sukuna’s hands come to your thighs, thumbs pressing into soft flesh, not bruising, just claiming space.
He pokes, squeezes, probes like he’s cataloging you the way you catalog him.
He has no shame about curiosity.
He never has.
When he pinches lightly, you swat at his wrist.
“Stop that.”
He catches your hand with his other one, claws careful not to scratch. He holds it for a moment longer than necessary, eyes on your fingers as if he’s comparing them to his.
“Soft.” he says again, the word still half-insult.
“Human,” you reply, and you’re not sure which of you is repeating the other anymore.
His gaze drops, and his mouth brushes the inner side of your thigh.
Not deep, not violent — a controlled nip that stings like a thin line of heat.
You inhale sharply, fingers curling into the sand.
“Sukuna—” you warn.
He doesn’t bite again. He licks, slow, deliberate, tongue rougher than any human’s, a texture made for water and friction.
The sting eases into a pulsing awareness that makes your skin feel too awake.
His pupils widen, dark swallowing most of the red ring.
For a second he looks less smug and more satisfied, as if the taste hit something in him that quieted the edge.
“You bleed easy.” he murmurs.
“You bit me.” You grumble.
He lifts his gaze to your face.
“Still blood.”
You swallow.
“Are you done?”
Sukuna’s mouth curves.
“Not yet.”
You should be furious, should push him off and stand up and remind both of you that this is dangerous.
Instead, you breathe out slowly and say.
“Then keep it controlled.”
Sukuna pauses, eyes narrowing, like your calm is more interesting than your anger.
“Say stop.” he says, low.
You meet his gaze.
“If I say stop, you stop?”
His jaw shifts.
“Yes.”
The promise has become ritual.
It should feel clinical. It doesn’t.
It feels like a thread you can hold onto when everything else in this place is made of glass.
Later — hours later, after you’ve rinsed and written and forced your mind back into “research” — you ask him for something else.
Not because you want to.
Because you don’t want the board’s hungry hands on it first.
You sit at the waterline with your notebook, tanktop, shorts, and a pen that keeps slipping between your fingers because your palms sweat.
Sukuna surfaces close, resting his forearms on the shore ledge, eyes bright with that quiet, cruel amusement he gets when he knows you’re about to embarrass yourself.
“Appendages.” you say, forcing the word out like you’re reading from a manual.
His mouth curves.
“You finally ask.”
“Shut up.”
He shifts his weight, and the movement is fluid, controlled — his shark half adjusting under the surface while his torso stays steady above.
He reaches down, fingers disappearing briefly beneath the waterline, then lifts his gaze back to you.
“You look,” he says. “No touch until I say.”
You hate that you obey instantly.
“Fine.”
He gives you a slow, satisfied blink, then moves again.
You keep your eyes on the notebook for a second longer than necessary, writing the words as if anchoring them will keep your pulse from betraying you.
When you look up, you force your face into something neutral — scientist, not lonely woman in a glass house.
Sukuna watches you watch him, smugness curling at the edges of his expression.
You can see his whole self when he lays like that — horizontal, humanoid and shark-like parts above the water, resting on the shallow part of the shore.
He doesn’t make it easy. Of course he doesn’t.
He drags out the moment like a lesson, letting you sit in the heat of anticipation and embarrassment.
When he finally allows you closer, you scoot forward on the sand, careful not to slip, careful not to rush.
You keep it clinical.
You keep it measured.
Your hands move with the same deliberate gentleness you used on his teeth.
You observe shape, texture, placement, the way his hybrid physiology solves problems in ways your textbooks never accounted for.
You note the band of dark pigment near the base of his lower cock, the way the skin shifts and adapts between air and water, the way everything about him is built for function and dominance at once.
While his lower cock looks more human-like, big, thick, a flared glans that matches the tone of his torso’s skin, a little pointy at the edge — his upper cock looks like a tentacle. Broader at the base, thinner at the end, like a long tongue, but with a slit at its edge, similar to his glans.
You wonder if both have similar properties, sensibility, function.
You press lightly, touch carefully to test temperature, skin, texture, softness.
He lets out a huff at some point, but doesn’t move.
Sukuna watches your face the entire time, eyes bright with the quiet pleasure of making you do this without fleeing.
“You pretend,” he murmurs. “Professional.”
“I am professional.” you snap, and your voice comes out higher than you want.
His grin deepens.
“You blush.”
You look down at your notes so fast you almost cramp your neck.
“I’m writing.”
He hums, pleased.
“Write more.”
You grit your teeth and continue, forcing your hand steady.
When you’re done, you pull your hands back, rinse them in the shallows, and pick up the pen again. Your notes are neat, tight, more thorough than anything you’ve ever sent the board.
These pages are for you.
Sukuna’s hand catches your wrist as you lay the notebook on the dry sand.
His lower body is back in the water.
You go still, breathing careful.
He holds you without squeezing, claws pressing lightly against your skin.
His gaze drops to your pulse point as if he can see it jumping under his fingers.
Sukuna settles his forearms again, relaxed like he hasn’t just made your pulse visible in your throat.
“My turn,” he says.
You don’t look up right away.
“We already traded.”
He hums.
“Not this.”
Your chest tightens.
“Sukuna—” you try.
He leans closer, voice low and sure.
“You always learn me. Now I learn you.”
Two years ago, that sentence would’ve been a threat that made you sick.
Now, it still makes you shake, but the shaking isn’t only fear.
It’s the strange, quiet reality that he’s become the only person who touches you with any honesty in this place — no pretense, no politeness, just a blunt attention that treats your reactions as real.
His hand slides down to your fingers, then releases you and plants on the sand again, bracketing you.
He leans forward, and the space between you shrinks until you can feel the heat of him against your knees.
He doesn’t lunge.
He doesn’t force.
He waits, and the waiting is its own pressure.
Sukuna’s hands come to your thighs when your expression gives him what he wants.
Warm. Heavy. Unavoidable.
He spreads you with ease, not forcing, not rushing — just making space the way he makes space in the water when he swims, as if the world should part around him.
Your face burns anyway, because you are still shy in ways you can’t seem to kill, and he knows it.
He likes it.
He uses his teeth to catch the fabric covering your sex and pull, the material giving way too easily under serration meant for meat. Your shorts and underwear are gone in a second, they never stood a chance.
The sound is small and obscene in the quiet of the House.
You gasp, a strangled sound you try to swallow, and your cheeks go hotter because he hears everything.
Sukuna pauses — not out of hesitation, out of control.
He inhales slowly, and you feel the warmth of his breath against you, the way his attention narrows until it’s almost tangible.
He looks up at your face, eyes wide, pupils blown.
“Still okay.” he says, and it isn’t a question the way it used to be.
It’s a demand that you be honest.
You swallow. Your hands curl into the sand.
“Yes.”
Sukuna’s mouth curves, satisfied — never gentle, but contained in a way that makes your chest ache with the strange safety of it.
He lowers his head again, you keep your breath steady.
When his hands shift — when his thumbs press into the softer parts of your inner thighs, when he tests what makes you tense and what makes you go loose — you find yourself grabbing at his hair without thinking, fingers tangling in damp strands at his temple.
Sukuna stills at the contact, as if the touch registers as a choice.
Then he continues with slow, relentless focus, learning you the way he learns everything — through attention, through patience, through the quiet arrogance of someone who knows he can take his time.
He spreads your folds, slides the rough pads of his fingers outside, inside, pinches and looks closely when you twitch and clench around nothing. He presses at your nub with a claw and you jolt, which amuses him, you notice.
The House’s pumps keep breathing, the tide keeps moving, the ceiling glass holds the sky far above you like a distant promise.
And eventually, when your muscles stop fighting and your mind stops trying to turn every sensation into a category, you let your head fall back against the sand and you exhale a sound you didn’t mean to give him.
Sukuna’s eyes lift again, watching your face like it’s the real study.
He pulls back just enough to speak, voice rough.
“You hide.”
You blink, dazed.
“What.”
“You hide sound,” he says, and his tone is both mocking and... almost annoyed, as if you’re denying him data. “Why.”
Because you were taught to be quiet.
Because you were taught your desire is shame.
Because you’re in a facility that will call you hysterical for feeling anything at all.
You can’t fit all that into words.
So you manage.
“Habit.”
He scoffs softly and returns to you, not allowing the conversation to become refuge.
You answer with your body — by staying, by not pulling away, by letting him see what he’s doing to you.
His breath warms your skin.
His eyes half-lid.
He stops testing with his hands and tests with his face, diving in between your legs and nuzzling the patch of kempt dark hair on your mound while his lips tease your clit without warning.
You tense. He opens his mouth and his long tongue unrolls to probe at your slick folds, sliding between them to taste you.
The sensation is immediate and overwhelming, not because it’s graphic, not because it’s violent, but because it’s different — his tongue broader, rougher, built for water, pressure, and the relentless patience of a predator that doesn’t tire.
You gasp despite yourself and press the back of your wrist to your mouth to muffle the sound, embarrassed even though there’s no one to hear.
Sukuna’s hands tighten slightly on the plush flesh of your thighs, keeping you open, anchoring you.
He doesn’t rush.
He takes his time in a way that feels like a message — I decide the pace.
Your body reacts with betraying ease, heat coiling low and spreading upward, making your thoughts smear at the edges.
You try to keep it in your head, try to keep it labeled — stimulus, response, nerve clusters, behavior conditioning — anything to keep from drowning in how intimate it is to be touched like this by someone who has learned your language and uses it to ask for your consent like a knife to the throat.
You fail.
You make a small, broken sound anyway, and Sukuna’s eyes lift again, watching your face as if that’s the true reward.
He shifts his mouth slightly — pressure changing, angle changing — and you feel your legs tremble under his hands.
You bite down on your lip hard enough to sting and hate yourself for how your body welcomes it.
His hands slide up, thumbs pressing into the softer flesh near your hips, kneading lightly as if testing, exploring, learning the way he always does.
You can’t stop thinking about the board calling you emotional, about the way they’d sneer if they saw you like this, about how they’d weaponize it, call it proof you can’t be trusted.
But you also can’t stop the truth — this is the first time in months you feel fully here in your body instead of trapped in your head.
Your fingers dig into the sand. Your spine arches slightly despite your effort to stay composed.
Sukuna’s hands press you down, not harsh, just firm, steadying.
“Look.” he says, and there’s command in it.
You hesitate, then lift your gaze.
His eyes are fixed on you with an intensity that makes your chest ache.
He looks... hungry, yes, but also focused, as if you’re the only thing in his world worth studying.
“You are mine.” he says.
The words should make you scared, probably.
They should make you fight.
Instead, something in you loosens further, because mine is still better than asset, still better than specimen, still better than the board’s cold language that reduces living bodies to value.
You swallow.
“I’m not—”
Sukuna nips your thigh again — not deep, not cruel — enough to make your sentence dissolve in a mewl.
You inhale sharply and glare down at him.
He looks smug.
“You talk too much.”
You laugh once, breathless and disbelieving.
“Says you.”
His eyes gleam again.
He returns to his work with slow, relentless attention, and you stop trying to label it because the labels don’t matter anymore.
He learns you quickly, he repeats his motions that have you squirming, he picks pace when he hears your breath hitching, he pulls you closer and sinks his tongue inside of you when he feels how your muscles twitch under his palms and your body heat spikes as your lust uncoils in your lower belly like molten lava.
When the edge finally comes — when your body tightens, when your mind blurs into a single, bright line — you reach down and touch his head, fingers sliding into wet hair at his temple again, and the contact grounds you.
Sukuna stills immediately at the touch, not because he’s startled, but because he registers it as a choice.
He looks up again, eyes wide.
“Stop?” he asks, voice rougher now.
You shake your head, breath shaking.
“No.”
He watches you for a second longer, then continues — slower, controlled, as if he’s guiding you over the threshold instead of forcing you off it.
When it finally breaks through you, it doesn’t feel like fireworks. It feels like something unclenching that you didn’t realize you’d been holding since you arrived here.
You exhale a sound you can’t swallow back.
He has you arching and gasping, clenching around his tongue as he takes your orgasm as a triumph, latching his mouth on your cunt and letting those sharp teeth graze lightly on your mound and puffy lips.
You whine his name at the sensation and the lingering fear that he will bite you just because he can be a bastard sometimes, but he slowly slides his tongue out of your tight core, lapping at it once before licking his own lips.
Sukuna stays close, mouth lingering for a moment longer as if savoring the aftertaste of your reaction, then pulls away and rests his forehead briefly against your lower belly.
The gesture is shockingly quiet.
Not affectionate in a human way.
More like... claiming, grounding, listening to the way your body calms.
His hands loosen on your thighs.
“More.” He says, lowly, voice gravelly, raising his forehead from your belly to look at you — pupils blown wide, deep black swallowing bright red, his gaze scorching your skin.
You feel like he’s looking through you, not at you.
Your heart beats fast once again, blood rushing in your ears but you have already lost that thing that kept you at least three feet away from the jaws of an apex predator.
Common sense.
You nod at him and that’s all he needs to pull back his torso just enough to flip you to your belly and drag you further down into the water.
You yelp because the sensation of being dragged in sand is never incredibly pleasant, and you settle your forearms and knees however you manage on it to keep your head above the water.
He’s hungry. He’s still paying attention.
His massive shape cages you with two strong arms before one of them wrap around your torso diagonally, a clawed-webbed big hand encasing the front of your thin neck almost fully and dragging a low groan from your throat.
He uses it to keep your head above the water. He fixes his elbow on the et sand right in front of your sternum, between your boobs. If he’s not careful he can end up strangling you.
You trust he won’t.
His other massive, warm, clawed hand travels up from your thigh to your waist with abandon, squeezing lightly, feeling you up and anchoring you as he moves up, leaning in until his broad chest presses against your shirt covered back.
You can feel him slightly against your skin where the shirt rode up with the slow movements of the faint waves in the tank.
You take a deep breathe and look up at his face towering just above your head.
Dark eyes, giant pupils swallowing the flame of his irises like two black holes that make you feel like you’re the next one being consumed.
He is truly magnificent.
Painfully so.
You part your lips, meaning to say something about his face but what leaves your mouth is a loud, ragged mewl as he — no warning, no nothing — bucks his lower half in, flared head of his thick lower cock pressing, breaching, sliding inside and stretching your tight cunt in a crude, sharp thrust that has him bottoming out inside of you at once.
You see white at the edges of your vision and the pain burns in a bright way.
The stretch is painful, your velvety walls fluttering, clenching and trying desperately to adjust to that girth and size. You gasp, pant and whine, fingers curling in the sand as your body jerks and writhes uselessly under his weight.
His claws dig into your skin, fingers closing around your neck and feeling your pulse spike.
He lowers his head until he’s basically looking at you upside down.
He licks at your cheekbones, tasting your tears as he feels his cock twitching inside you, being massaged by your warm walls, basking in the delicious feeling of your pussy gripping him in a tight vice. His upper cock lays between the curve of your ass, leaking against the small of your back.
Your breathes are still ragged and wet with your sobs as he slowly pulls himself out until only the fat head of his cock stays inside.
You feel the difference, you feel empty suddenly without that massive intrusion — but soon you learn that he did it so he could fill you up even more.
Unlike a human man, he doesn’t let go of your hip or your neck to fidget with his cock and align it with your entrance.
No — he bucks his hip again, adjusting, pressing, and you feel that pointy tip of his upper appendage sliding in between your ass cheeks, intruding, probing at your puckered rim.
You jolt and your body shivers, but he takes mercy on you.
His big hand lets go of your throat and cups your jaw, keeping your face up, keeping your eyes on his.
“Relax.” He orders, voice low, almost gentle.
“Won’t fit— Sukuna— fuck,” you feel the panic uncoiling inside you.
He lowers his head again, this time he settles it besides yours, his cheek — warm, wet — presses against your cheek and he breathes deeply once, twice, three times, forcing you to match his rhythm until your heart stops hammering your ribs.
“Relax.” He repeats without moving his head, and you slowly, very slowly, feel your body relaxing under his ministrations.
He moves, unhurried this time. He rocks his hips, the tip of his cock dragging in and out, in and out, erring to leave your cunt but never doing so as the pointy tip of his upper cock pokes, presses and finally breaches your tight asshole.
The stretch is still painful, weird honestly, but he slides in so much easier even though you’re so, so much tighter there.
That upper dick is made for lubrication and oviposition, you manage to remember as he presses and pushes his powerful hips, spreading you open inch by thick inch.
He reminds you to breathe with a squeeze on the hinges of your jaw, and he grunts, heavy, luscious, once he finds himself completely sheathed by both your hot, cozy holes.
Fuck, you’ve never felt so fucking full.
You can feel your lower belly bulging from how big he is. How both his cocks consume every single inch avaliable.
You don’t really know how you managed to fit him inside, but you won’t think about it now.
Now you can only think about the hand leaving your waist to sneak up under your shirt and bra, pulling it up with no patience just so he can freely feel and cup one of your breasts, granting him another dragged moan from your lips as he squeezes it lightly.
“Soft.” He murmurs, as if you didn’t already hear that many times from him.
“You’re fucking big.” You catch yourself confessing instead of cursing him, a little breathless.
You feel his grin widening, his cheek is still against yours, and you feel the rumble raising from deep don his chest — which is still pressed against your back, mind you — in a dark noiseless chuckle.
He knows he’s big, and he likes he’s stretching you to his shape.
Because he knows you’re his.
He decided it, he claimed it and he’s doing it again.
“Fuck.”
It’s not a curse, it’s a warning.
And it takes shape in a single beat as he starts to actually move, slow, languid thrusts at first, because he’s not breaking you. He’s keeping you. And still they have you panting and mewling, brows knitting together as your body takes his size again and again.
Your knees scrap on the soft giving of the sand underwater, your hands find purchase around his wrist and forearm — that one still supporting your head by the jaw.
And he is fucking you partially underwater, so the sensation is simply unique in so many ways. You’re lucky there’s no sand intruding to turn it into a terrible experience.
He slowly picks his pace and you can feel the restrains snapping one by one as his movements grow rougher.
His claws sink into the soft flesh of your hip once his hand is back there to anchor you better as he fucks into your ass and pussy in a now ruthless rhythm.
His chest is not pressed against your back anymore and his face once again looms over your head with his hunched form — still he cups your jaw, keeps your face from the water, keeps his eyes bored into yours, transfixed, almost etching his lust in your body with each powerful snap of his hips against the fat of your ass.
You’re far gone when he starts to rut inside of you like a beast in heat, hammering his cocks in and out so viciously the water splashes every-fucking-where, but he doesn’t care and you’re too fucked out to even notice.
His hand explores and squeezes your plush flesh with abandon, and it finds your bundle of nerves between your legs again, pressing on it, circling, sliding and rubbing just to hear your screams and broken moans as he keeps stretching and pounding into you restlessly.
He pries out of you three, four orgasms in the span of five hours he keeps you at his mercy, releasing almost two years of gathered tension when his thick cum spurts inside of both your holes — not just once, probably half a dozen times — and it keeps being pushed out by the relentless thrusting only to be refilled again and again.
Your throat is hoarse of calling his name, begging, crying and moaning, your hands once closed around that wrist of the hand keeping your head up and then fell, limp, again on the sand.
Your eyes have rolled back and your body spasmed with every orgasm, every high you rode as he made sure to carve his shape inside of your warm, velvety walls.
Maybe he simply grew addicted too fucking quick at the hot, tight sensation of your human pussy and ass squeezing and milking his appendages.
Maybe he really needed to release all of the semen he has produced during the years he was kept.
Maybe he just couldn’t stop once he heard your cute mewls and moans escaping.
Whatever reason got him so frantically mounting and breeding you again and again, you’re free to explore once you regain your conscience.
Which, miraculously, happen while he’s still sheathed inside of you, chest heaving, cocks pressing deep, deep inside, purging the excess cum and water out of your holes as his body seems to finally need some rest.
He manages to get you further up in the shore, sliding slowly out of your ruined gaping entrances as he allows you to plop on the sand properly, tired, muscles sagged.
You’re shaking, sand sticking to your skin, hair damp at your temples.
You feel exposed and heavy and strangely clean, like something sharp has been pulled out of you.
You don’t move at first, just breathe, shallow pulls and little, soft moans and sobs.
He keeps his hand cupping your jaw to keep it elevated from water and sand, his cocks are tucked in again inside that subtle slit on the shark-half of his body.
He adjusts you to lay on your side, head able to look at him when you open your eyes and they can focus once again.
Sukuna lifts his head when your eyelids flutter open, his eyes still wide.
He looks... pleased.
Not in a triumphant way. In a way that makes your chest tighten, because it hints at a need he won’t ever admit.
You swallow and manage, voice still hoarse and mind scrambled.
“That was... a trade.”
He snorts softly.
“Everything is trade.”
Your thoughts travel towards the notebook, toward the research pages waiting to be filled.
“And now... you’re going to let me pretend... this is all science.”
Sukuna’s grin turns sharp again, familiar.
“You will write. You will lie to them. You will keep for you.”
Your breath catches, you furrow your brows. A little bit of life returning to you as you realize.
“You know I’m lying.”
He leans closer, voice low.
“I know you choose me.”
The words are simple, the meaning isn’t.
You stare at him, throat tightening, and the fear returns — not of him, not of teeth, but of what the board will do when they realize your subject isn’t just learning words.
He’s learning humans.
He’s learning leverage.
He’s learning you.
“You heard the call,” you whisper. “They’re coming.”
Sukuna’s gaze sharpens. The smugness fades into something colder.
“Team,” he says, tasting the new word. “Many.”
“Yes.”
He glances toward the far end of the facility, toward doors and locks and the invisible world beyond the glass ceiling. When he looks back at you, there’s a flat certainty in his eyes that makes your stomach twist.
“They will try take.” he says.
You feel your throat close.
“I don’t know what they’ll do.”
Sukuna’s hand rises and cups the back of your knee, claws careful, not scratching. His thumb presses lightly into the soft spot like a reminder of his control — but also, strangely, of his presence.
He looks like he’s considering grabbing you and taking to the depths of his tank.
“You will tell me,” he says.
It’s not a request.
It should terrify you.
It also steadies you, because it’s something solid in a situation that keeps shifting under your feet.
You blink hard, forcing yourself back into motion.
Your body is sore, your mind is still fuzzy. You can’t really sit down and you make a face when you realize it.
You reach for your shirt — you’re still laying on your side, still with his big hand holding your face — bunched up with your bra above your boobs and pull it back down with clumsy hands.
Sukuna watches you redress with a kind of quiet satisfaction, like he’s letting you rebuild your armor while still knowing what’s underneath. Your shorts never left, they’re simply ruined in the middle and that’s how he could ruin you with his tongue and his cocks.
He takes another mercy on you.
Letting go of your head slowly, he reels himself up so his upper body is flat on the sand, his back pressed on it, and his lower body still mostly in the water.
He’s big enough, large and strong enough to support you, and in one fluid movement he reaches, grabs and hauls you over his torso.
You yelp once again and he simply lays your flimsy human body on top of him.
Chest to chest.
He’s uncomfortable, that position has to be terrible for him, but he’s the sole responsible for your lack of... well, everything. You really feel sore to your bones.
“Rest.” He rasps an order, keeping one arm wrapped around your waist to keep you from sliding off him or trying to get up, the other bent behind the back of his head to use his forearm as a pillow.
“Just a little.” You mumble and let yourself relax over him. He’s warm, and he’s firm under you. At this point you don’t even care that you’re wet, that he’s wet, that your skin will become wrinkled — it already is from how long you’ve been kept submerged as he pounded into you.
You close your eyes and let your mind drift, let yourself rest for a while until your body decides to let you move again.
You slide off him when you wake up, not mentioning how you have drooled on his chest. You manage to walk, still a little wobbly, to the shower where you take a hot bath, washing off the sweat, the sand, the salt and the remaining cum that drips off your sore sex.
That was, indeed, a trade.
You don’t sleep yet, you change your clothes, put another short, another shirt and walk back to the shore where he has simply rolled his massive body to a better position now that he doesn’t need to function as a water mattress for you.
You grab your notebook, flip to a page that isn’t part of the official log — no headers, no facility codes, no neat categories. Just your handwriting, private and dense.
You write — TEAM COMING. NO DETAILS. SUBJECT AWARE.
“Language,” he says, as if it’s obvious. “You make marks. You speak. I want.”
Your pulse jumps.
He’s moved beyond speaking.
He wants literacy.
He wants access to everything you’ve tried to keep behind pen and paper.
A year ago, you would’ve laughed. Now, you just feel cold.
You force your voice steady.
“If you can read, they’ll... they’ll never let you go.”
His eyes narrow.
“They already not let go.”
That simple truth hits you like a slap.
You exhale slowly.
“Okay. But not everything.”
His mouth curves.
“You keep secrets.”
“Everyone does.”
He watches you a beat, then gives a slow nod — acceptance, not agreement.
He understands secrets.
He just doesn’t like when they aren’t his.
You begin with simple words, the same way you started speech — TABLE. WATER. SAND. YOU. ME.
You point. You write. You read aloud.
Sukuna watches, absorbs, repeats, his mouth shaping the sounds while his eyes track the letters with unnerving focus.
He learns faster than you want him to.
By the end of the week, he’s picking out words from your taped labels without prompting.
He taps the glass near the kitchen and says “SINK” with almost perfect clarity, then looks at you as if daring you to deny him.
By the end of the month, he’s staring at your official logs when you write, head tilted, gaze moving left to right like he’s mapping patterns.
You start hiding your private notebook under the mattress again, like a teenager with contraband, and the shame of it makes you want to laugh.
The next time the board calls, you give them what they want — numbers, observations, a controlled slice of Sukuna’s behavioral knowledge:
Aggregation around resource-rich zones.
Dominance signals through nudges and body contact.
Opportunistic coordination during hunts.
Individual variation in sociability.
You omit the words “choice” and “mine.”
You omit the way he asked to read.
You omit the way he asked about after.
When the call ends, you find Sukuna at the shore ledge again, waiting like he always does.
He doesn’t ask what they said.
He doesn’t have to.
He watches your face, your shoulders, the way your hands move too fast as you put the phone back.
“You lied,” he says, calm.
“Yes.”
He looks pleased.
“Good.”
You swallow, and the weight of what you’ve become presses against your lungs.
“You can’t keep doing this,” you whisper. “You can’t—” you gesture vaguely between you and him, the intimacy, the trades, the quiet dependence. “They’ll use it.”
Sukuna leans closer, eyes bright with something dangerous.
“They already use you.” he says.
The words hurt because they’re true.
He reaches out, claws careful, and hooks one finger under the edge of your sleeve, tugging lightly — not to tear, not to force, just to pull you closer until your knee brushes the damp sand at the waterline again.
“Come,” he says.
You should refuse.
Instead, you sit.
You let your feet sink into the shallows.
You let the water climb your ankles.
Sukuna settles half-out of the water beside you, shoulder near your thigh, the heat of him bleeding into your skin as it did countless times before. He looks up at the glass ceiling, at the slice of sky beyond, and you follow his gaze automatically.
The sky is bruised purple tonight. Stars are faint behind cloud cover, but they’re there.
You feel him shift slightly. His claw touches your calf, drawing a slow, absent line — not quite a caress, not quite a claim. Something in-between that only exists because you’ve spent a year teaching each other new ways to exist in the same cage.
“You are afraid.” he says, not as an accusation this time.
“Yes.” you admit, and your voice is smaller than you want.
He exhales, a low breath that stirs your skin.
“Good,” he says, and the word is strange — almost gentle, if you don’t think about it too hard. “Fear make you watch.”
You turn your head toward him.
“And what do you watch?”
His eyes slide to you, sharp and steady.
“Doors.” he says.
Your stomach drops.
“You can’t—”
He cuts you off with a quiet, amused sound.
“You think I only learn words?”
You stare at him, heart tightening.
Sukuna’s mouth curves, and the expression is all teeth again — ominous, confident, cruel in the way only someone certain of their own strength can be.
“Team will come,” he says, voice low. “They will try take. They will try hurt.”
His claw presses into your calf slightly, grounding you.
“And I,” he adds, eyes locked on yours, “will choose.”
The threat isn’t loud.
It doesn’t need to be.
You swallow hard, staring up at the dim sky through reinforced glass, and the prison feels suddenly like a thin, fragile thing — sand and water and metal pretending it can hold a creature who’s started to understand exactly where the seams are.
Beside you, Sukuna stays half on shore, half in water, close enough that your body stops shaking.
He listens while you talk about nothing again.
He lays his head on your thighs, forearms bracketing your hips, claws half-digging in sand.
He allows you to play with his pale hair without punishing you.
ETHOGRAM ENTRY I — Week 1–8: Acclimation, Refusal, Observation
They don’t call them merfolk at first.
They call them interference — the sort of word men in uniforms use when they want something to sound technical enough that you stop picturing it. Interference in sonar returns. Interference in shipping routes. Interference in the water column that makes instruments stutter and screens bloom with static.
Then the word changes to asset when they start to believe the interference is alive, and to threat when the first bodies wash up with wounds no propeller can explain.
You’re still in grad school when the footage leaks for the first time — grainy, stolen, timed wrong so the date in the corner flickers between two numbers like it can’t decide what decade it belongs to.
A Coast Guard helicopter hovering over midnight black water.
Men shouting into headsets.
Something pale rolling under the surface, too long to be a shark, too deliberate to be a wave.
The second leak is worse, because it’s close enough to force the brain into detail.
A fishing boat half-caved, deck slick. A torn net that looks chewed. A hand — human — still locked around a rail, knuckles white with death. And below it, caught in the floodlight sweep, a face that shouldn’t exist — high cheekbones, a heavy brow, eyes reflecting red like a fox’s in headlights, a mouth opening in the water to show teeth laid out for cutting.
After that, nobody laughs when the old men in coastal towns talk about sea devils.
Nobody tells the widows they’re exaggerating.
The government does what it always does when the ocean produces something inconvenient — it builds vocabulary around it until it can pretend it’s in control.
By the late seventies the public gets a story — migrating predators, rising aggression, “unknown species interactions.”
By the eighties the ports get posters that tell you what to do if you see “unidentified marine life with human-like features.”
By the early nineties, the sea has been carved into zones and the zones have been carved into budgets.
And in quiet rooms where the air smells like stale coffee and copier toner, men decide that if something can be caught, it can be studied.
They don’t only find one kind.
That’s the part that turns the world in a direction it can’t walk back from.
It isn’t a single myth. It’s a spectrum.
Bodies that move like seals with hands that can grip.
Bodies that sing like whales with throats built for speech and lungs built for pressure.
Bodies that cut through currents like sharks, all power and patience, and a kind of attention that doesn’t look away once it lands on you.
Humans start naming them the way humans name anything they intend to own — by taxonomy, by function, by threat level.
There are binders with laminated sheets. There are classifications for fin shape, dentition, dermal texture, vocal range.
There are notes on tool use — yes, observed.
On social behavior — varies.
On territory — absolute.
The first attempts to approach end with blood in the water.
The next attempts come with guns.
They learn fast — the ones in charge, at least.
They stop sending divers and start sending cages.
They stop trying to coax and start trying to trap. They drag things up from trenches and coastal shelves like they’re hauling nets of tuna, and when what’s inside those nets screams — when it curses, when it bites through steel, when it looks a man in the face and understands — somebody writes a memo that says containment priority and another that says communications potential.
It’s in that world that you become useful to them.
Not because you’re naive.
Not because you’re eager.
Because you’re the wrong kind of person in the wrong kind of building, and they can spend you without losing anything they value.
A woman in a men’s field.
A woman in a men’s world.
You’re a marine biologist with a mouth that doesn’t stay shut when it’s told to.
You grew up with salt under your nails and a father who taught you to respect the ocean the way you respect a stranger with a knife — carefully, without entitlement.
You got your degree on scholarships and spite and the promise you made to yourself that you’d never become one of the people who treat living beings like resources.
Then you wrote a paper — one that argued, plainly, that the “unknown species interactions” were deliberate, intelligent, and likely social.
You used the word people once.
Just once.
In the wrong journal.
It got you laughed at in faculty lounges and noticed in offices you didn’t know existed.
The call comes on a Tuesday. Not a phone call in the casual sense, a message delivered through your department chair with a sealed envelope and a suggestion that you dress professionally.
The meeting is held in a building that doesn’t have a sign.
The hallway carpets swallow sound.
The men inside have smiles that don’t reach their eyes, and they keep calling you Doctor like it’s a leash they’re testing for strength.
They tell you it’s an opportunity.
They tell you it’s a national security matter.
They tell you you’ll be compensated, that your work will matter, that you can help set ethical precedent from the inside.
One of them says, with a practiced softness, that women bring a certain patience to communication studies.
Another says you’ll be safer than their male staff because the subject will perceive you as less threatening.
It’s almost funny, in a way that makes your stomach clench, how easily they speak around the truth.
You don’t volunteer.
You don’t sign with enthusiasm.
You argue, you demand to see oversight, you ask what happens if you refuse.
A man with gray hair and a ring that looks too expensive for his hand leans back and regards you like a specimen.
“If you refuse,” he says, “we will find someone else. Someone who doesn’t believe these things are people. Someone who will do what they’re told and call it what it is — science.”
You picture a cage, a living being dragged into it and left there with nobody who thinks it matters.
You hear yourself say, thin and controlled.
*“Where is the facility.”
That* is how they win.
Not with persuasion, with the fact that they can always choose worse.
They fly you out two weeks later.
The transport is unmarked, paperwork calls it a research posting and lists a coastal address that leads to nothing but rock and scrub on any public map.
They hand you a binder with protocols that read like instructions for handling explosives.
No direct contact unless authorized.
No unsecured food items.
No swimming.
No entering the water environment.
No approaching the subject during feeding.
As if these rules exist to protect you, and not because they can’t afford to lose the asset.
The facility is isolated the way prisons are isolated — not because it’s beautiful, but because distance is another lock.
A stretch of coastline where cliffs bite into gray sea, where wind that tastes metallic — the kind of place where even gulls don’t bother to linger.
From the outside, it looks almost modest — low buildings, reinforced doors, power lines buried.
Once you’re inside, the scale reveals itself in pieces — hallways that lead to corridors that lead to a central structure built like a bunker.
They walk you through the “house” last, like they’re saving the main attraction.
It’s called the Hybrid Habitation Unit in the documents, though no one says the full name out loud.
In conversation, it’s the House.
As if giving it a familiar label will make what happens inside feel domestic instead of controlled.
They open the final door and you smell chlorine and salt at once.
The air is cool, kept at a temperature that makes skin want to gooseflesh.
The House is immense.
Two stories, open plan, no interior walls except where plumbing demands them. One half is land — tile and concrete dressed up with pale sand that has been sifted clean, a sloped “shore” that meets water with a gentle, artificial tide.
The other half is water — an enclosed ocean made of reinforced glass and engineered currents, deep enough that the far end disappears into darker blue.
A wall of glass divides the environments like a line drawn by a nervous god.
Not a window — a barrier designed to hold back a body with the strength of a machine.
There are cameras mounted high, but they aren’t wired.
They tell you they’re for later installation, because they can’t risk transmitting anything from this site, and it’s secure enough that they don’t need surveillance inside the House yet.
You don’t believe them.
You also don’t see any obvious microphones, and you realize with a slow, unpleasant clarity that the lack of constant monitoring is not trust. It’s neglect. It’s the kind of oversight that happens when the people in charge think the two lives inside are expendable.
A scientist you haven’t met before — thin man, nervous hands — stands beside you and gestures toward the water.
“He’s at the back,” he says, like he’s talking about an animal in a zoo enclosure. “We’ve been observing baseline behavior.”
“He.” you repeat, not as a question, as an insistence.
The man’s eyes flick away.
“Specimen C-3. Selachian-hominid hybrid. Captured in coastal waters after—” he clears his throat. “After several incidents involving missing divers.”
You turn your gaze into the tank.
At first you see only water and the slow drift of particulates.
Then something shifts in the darker end, and your brain locks onto shape the way it locks onto a threat.
A tail.
Not a fish tail from a fairy tale. A great white shark’s tail — immense, crescent-shaped, built for speed.
It moves with lazy economy, a single sweep that displaces water in a way you can feel through the glass as pressure.
The body attached to it is long and thick, scarred in pale lines that cut across grayish-salmon skin. There are dents in the dorsal fin, jagged bites out of it like old battles taken as trophies. There are netscore marks around the thickest part of his torso where something once cinched and cut.
And above the shark body, there is a man.
Broad shoulders. Muscular arms with membranes webbing between fingers, the skin stretched there like nature has designed him for water first and hands second. Claws at the tips — not delicate, not decorative. Practical. Black markings curl over his chest and across his shoulders in patterns that look like ink until you realize they align too neatly, too intentionally, like someone has painted a map of violence onto him. The tattoos continue down, disappearing into the grayish-salmon of his shark body in bands and lines that echo the same language as the ones on his human skin.
His hair is pale, almost a washed-out pink, drifting around his face underwater like seaweed.
His eyes are open.
Crimson.
Not bloodshot, not irritated. Just red, the way some animals’ eyes are red when light hits them wrong.
But this isn’t a reflection problem.
He’s in the dim end of the tank, and his gaze still catches, sharp as a hook.
Bored into you.
He watches you.
The scientist beside you speaks again, voice lowered as if volume might provoke something.
“He’s... intelligent,” he says. “We’ve tested problem-solving. He responds to patterns. He appears to understand—”
You don’t let him finish, because something moves near the surface and your attention snaps upward.
At the front of the tank, close to the shore-mimic, a second shape floats.
A body.
Not human. Not shark. Something in between — sleeker than the great white shark, with smoother skin and fins more like an orca’s, black-and-white bands dulled by death.
Mauled. Skin torn, bite and claws marking the ripped flesh — but there’s no blood oozing from it. It’s been dead for a while.
It turns slowly in the current, face tilted toward the glass as if still trying to look through it.
There are more bite marks in the torso that make your throat tighten.
You look at the man beside you, and your voice comes out cold.
“You put him in with another?”
“We needed to assess interspecies communication,” he says quickly. “We had reason to believe—”
“He killed it.”
The man swallows.
“Yes.”
You stare at the dead thing until the scientist shifts his weight like he can’t stand your gaze on the consequences.
Behind the glass, the great white merfolk doesn’t move toward the body.
Doesn’t show interest.
Doesn’t even look at it.
His attention remains on you, steady, almost bored.
Like he already knows you’re going to be the more interesting creature in this room.
They leave you alone that first day with a cart of supplies and a list of tasks.
Your living quarters are inside the House, on the land side — a bed tucked into a corner with no door, a small bathroom separated by frosted glass, a kitchen with a stove and cabinets stocked with canned food and vacuum-sealed packets.
There’s a desk facing the tank, paperwork already stacked there — forms for observation logs, for vocalization attempts, for behavioral notes.
A tape recorder.
A bulky early-model laptop that hums like it hates being awake.
They expect you to work.
They expect you to do what they want without question, because what are you going to do, walk out into the giant endless sea and call a taxi?
You set down your bag and stand for a long moment, letting the silence settle on your shoulders.
The water makes its own noise — the low churn of pumps, the soft slap of artificial tide against the shore.
Somewhere in the building, a generator thrums with the consistency of a heartbeat.
You can see him even from here.
Lurking at the far end, tail barely moving, body held in that effortless suspension that belongs to creatures built for water.
You lift a hand, almost without thinking, palm toward the glass.
His eyes narrow.
You don’t wave.
That feels like performance.
You keep your hand there, still, a simple acknowledgment.
After a beat, he turns away.
Not fleeing, not submitting — dismissing you like you’re a sound he’s decided not to care about.
The first week is a routine forced into your bones.
You wake to cold air and the faint sting of disinfectant.
You eat because you have to, you check the lock mechanisms on the doors because anxiety makes hands want something to do, you read the protocols until the words blur, not because you plan to obey, but because you need to know exactly what they’ll accuse you of breaking later.
Feeding happens twice a day.
A hatch in the ceiling above the water side opens with a hydraulic sigh, and a crate lowers down, sealed until it hits a platform just beneath the surface.
The first time, you watch from the shore, arms wrapped around your own ribs.
He appears from nowhere.
One moment the water is empty, the next the crate is surrounded by movement. A tail flick. A rush of pale-pink. His hands — those large, webbed hands — clasp the crate and tear it open as if the seals are paper.
Fish spill out, thick and bloody.
He takes them with violent efficiency, teeth closing, head snapping with the instinct of a shark and the deliberation of a man.
He eats like someone who has never had the luxury of slow meals.
You swallow down your nausea and make notes anyway — speed, posture, breathing breaks.
The way his eyes flick toward you between bites, checking your reaction.
The second time, you try speaking.
Not commands.
Not “Hello” chirped in a bright voice like he’s a pet.
You speak as you would to someone trapped in a room with you, someone who deserves to hear another voice even if he never responds.
“My name is—” you stop yourself.
Names matter.
Names can be used.
“You can call me whatever you want,” you say instead, and you hear how strange it is as soon as it leaves your mouth. “They want me to teach you. They want you to talk.”
His jaw works. He swallows. Blood clouds into the water around his mouth.
He doesn’t look at you.
But when he turns, when the last fish is gone and the crate sinks empty, his gaze slides across your face with a kind of appraisal that makes your skin prickle.
You keep talking anyway.
You tell him what day it is.
You tell him the weather.
You tell him you hate the smell of chlorine because it’s the smell of pools, not the ocean, and this place is pretending it can build an ocean out of cement and money — no matter that the actual, real ocean is separated from you two by only layers of concrete and very resistant glass.
You don’t expect him to care.
You do it because the silence feels like surrender.
Weeks pass.
The scientists come once, briefly, standing at the entrance like they don’t trust the walls.
They ask for progress.
They ask if he’s vocalizing.
They ask if you’ve attempted tactile contact.
You keep your expression neutral and tell them he is observant, responsive to patterns, noncompliant with direct instruction.
They nod as if that’s acceptable, because they don’t have to live here.
They don’t have to feel watched every time they turn their back.
When they leave, you sit on the sand-mimic shore and let the anger settle in your muscles like a toxin.
You start to understand the House as a stage designed for mutual visibility.
There’s nowhere you can go where he can’t see you unless you lock yourself into the bathroom, and even then you feel the weight of his presence across the glass wall, the knowledge that he knows the shape of your day now.
You cook.
You wash dishes.
You write notes.
You pace.
You sleep with your back turned toward the tank and still wake with the sense of eyes on you.
At first, he stays at the far end, a shadow with very sharp teeth.
Then, gradually, he begins to drift closer.
Not in a friendly way.
In the way an apex predator changes position when it decides a new part of its environment is worth monitoring.
He starts surfacing more often.
Hauling himself onto the shallow ledge where the water meets the mimic beach, resting with his torso out of the water and his shark body still submerged.
When he does, the air fills with the smell of him — salt, raw meat, something metallic like blood that never quite leaves.
The first time you see him fully in that posture, you forget to breathe for a second.
It isn’t only that he’s large.
It’s the combination of human familiarity and animal wrongness.
The way his chest rises with breath, ribs moving under tattooed skin, and below that the thick pale-pink-gray body that could cut you in half if it wanted.
The way his hands rest on the sand, claws half-sheathed, fingers spread to support his weight.
He closes his eyes sometimes, face tilted toward the overhead lights as if they’re sun. But you can’t fully believe he’s sleeping. Not when predators like this can rest with one part of themselves awake.
You learn his scars the way you learn maps.
A long pale line across his left pectoral, healed jaggedly, like a harpoon wound. Smaller nicks along the fin ridges that run down his shark torso. A chunk missing from the edge of his dorsal fin, the tissue around it thickened from recovery.
Someone tried to take him apart and failed.
You wonder who taught him to hate humans so specifically.
You also wonder if he ever hated them, or if he simply hunted the way nature designed him to hunt, and humans decided that being on the wrong end of teeth meant the creature with the teeth was evil.
Your compassion doesn’t erase the fact that he killed people.
It doesn’t erase the floating corpse you saw, turning slowly in artificial current.
It just keeps you from pretending the answer is simple.
You talk more on the days he surfaces.
Not because you think he’s learning — because there’s something in you that refuses to treat him like a silent object.
Because you can’t stand being the only human voice in this place without using it for something other than logging data.
You tell him about the first time you dove in open water without a guide rope, how the vastness made your body feel small in a way that was almost comforting.
You tell him about your research dreams, before this — the kind of work that involved observation without interference, studying ecosystems without touching them, the kind of science that doesn’t require cages.
You tell him about the men who sit in conference rooms and draw lines on maps as if the sea belongs to them.
Sometimes you catch his attention in small ways.
A twitch at the corner of his mouth when you curse under your breath about the food they send you.
A slow blink when you mention the word freedom in a sentence that isn’t a demand.
A shift in his posture when you say, flatly, “They put me here because I’m disposable.”
That day, his eyes open.
They fix on you with such direct focus that your spine straightens without permission.
You keep your voice steady.
“Don’t pretend you don’t understand that word.”
His nostrils flare.
He draws in air, and you realize how carefully he’s been listening, not just to your sounds but to the way your body moves when you make them.
He doesn’t speak.
Not yet.
But he doesn’t look away, either.
The first time you put your hand in the water is not brave, it’s a quiet kind of desperation.
It happens late at night, when the House is dark except for the muted underwater lights that keep the tank from becoming a black void.
The water side glows faintly blue, a false moonlight.
You can see him at the far end, suspended and still. Or you think you can. The water distorts, shadows shift.
Your eyes strain for the movement that would confirm he’s awake.
You sit on the shore ledge and slide your fingers into the water, just the tips at first.
The chill bites, the water laps against your skin with a gentleness that feels like mockery in this place.
Your pulse speeds up anyway, because the primitive part of the brain doesn’t care about ethics.
It cares about proximity to teeth.
Nothing happens.
You let your hand sink deeper until your wrist is submerged.
Feels nice as it adjusts to the temperature.
You keep your breathing slow.
You miss being able to dive, to swim, to float.
You imagine yourself as you used to be, floating in open sea with nothing above you but sky, nothing below but depth, trusting the ocean not to swallow you simply because it can.
The water moves.
A current shift, subtle.
You freeze so hard your shoulder aches.
You don’t pull your hand out right away.
You make yourself wait.
You refuse to let your fear dictate everything you do in this House.
A shape glides past in the deeper water, too far to see clearly, but close enough that you feel the pressure change along your skin like someone exhaled nearby.
You pull your hand out then, not fast, not panicked. Controlled. You wipe it on your pants as if that will remove the feeling of being noticed.
You go to bed with your heart still working too hard.
In the morning, you find a damp mark on the shore sand where something heavy rested in the night, close to where your hand had been.
It feels like a message.
By the second month, the boundaries between your job and your life have blurred into something ugly.
You write fewer logs than they want.
You speak less into the tape recorder.
You can’t bring yourself to reduce him to bullet points the way the protocols demand.
You keep your notes, but you keep them messy, human, full of questions instead of conclusions.
You also begin to understand that he has his own patterns.
He surfaces when you cook.
He lingers by the glass when you write.
He watches you eat with an intensity that isn’t hunger so much as study.
He tracks the rhythm of your day the way a hunter tracks prey movement, except you don’t fully believe he’s waiting for an opening to kill you anymore.
If he wanted you dead, he could have done it the first week.
Through the glass? No.
But there are hatches.
There are maintenance points.
There are moments when you have to lean close to the water to clean filters on the shore edge.
There are dozens of ways a creature like him could force a mistake.
Instead, he waits.
He learns.
You try to teach him words, eventually, because that is the assignment, and because part of you can’t let go of the idea that language might be a bridge instead of a weapon.
You draw symbols on waterproof boards.
You point to yourself, then to the word for human.
You point to him, then to the word for you.
He watches without moving, eyes following the marker tip.
When you repeat a sound, slow and careful, his head tilts slightly, the motion controlled as if he’s deciding whether it’s worth mimicking.
Some days he ignores the board entirely.
Other days, when you stop and set the marker down with a sigh, he moves closer to the glass and taps it once with a claw, a sharp click that makes you flinch.
You look up.
His gaze is steady.
Tap. Tap.
Not random, not impatience.
Rhythm.
You realize, with a strange jolt, that he’s repeating the cadence you used when you spoke earlier.
Not the words.
The pattern.
Your throat tightens.
You want to be pleased.
You also want to be afraid of what it means when something like him chooses to learn.
The day he touches you is quiet.
No alarms, no power failure, no storm.
It’s late afternoon.
The overhead lights have that hum they always have, the kind that sinks into the bones until silence feels wrong.
The water is calm.
The artificial tide makes a soft, steady sound as it creeps up and retreats, up and retreat, like the House is trying to imitate breathing.
You’ve been talking more than usual because loneliness does that to a person, your words have been spilling out with less structure, drifting into stories and complaints and little scraps of memory.
You’re sitting on the shore ledge with your feet on the sand where the water laps.
Not in the water.
Just close enough that the cool dampness kisses your toes.
You tell him, mostly to fill the air,
“When I was a kid, I wanted to be taken under. Not like—” you stop, hearing how it could sound. “Not to die. To be shown what the ocean looks like when it isn’t filtered through glass and research grants.”
Your toes curl as the water reaches them.
The sensation is small and grounding.
You glance toward him.
He’s on the shallow ledge, torso out, eyes half-lidded.
He looks like he might actually be resting.
His hands are on the sand, claws sunk slightly into the grit, tattoos stark against wet skin.
You exhale, slow.
“It’s stupid, I know. Humans always want what they can’t have.”
You don’t notice him move until it’s too late.
It isn’t a sudden rush.
It’s a controlled slide, the kind of motion that doesn’t waste energy.
One moment you’re watching the rise and fall of his breathing, the next his hand is in the water close to your ankle.
Your body reacts before your mind catches up.
You jerk your feet back, scraping sand, trying to put distance between skin and claws.
His fingers close around your ankle.
Warm.
Not slimy like you’d expect from fish.
His skin is textured, rough in a way that suggests dermal denticles, a surface designed to cut through water.
His grip is firm enough that you feel bone under it, not crushing, but absolute.
Claws press lightly, precise, as if he knows exactly how much pressure will break skin and chooses not to.
Your breath catches hard.
You grab at the sand with your hands, palms digging in, trying to anchor yourself like a child trying not to be dragged by a wave.
He pulls.
Slowly.
Not because he lacks strength.
Because he’s savoring the way your body panics.
The way your fingers scrabble for purchase.
The way your muscles tense in a futile attempt to resist something built to dominate currents.
You drag in a breath, sharp, and force your voice to work.
“Stop!”
His crimson eyes are open fully now.
Focused.
Watching every shift in your face, every tremor in your hands, like this is data.
He doesn’t stop.
You try to scoot backward, backpeddaling, hips lifting, but the angle works against you.
The sand gives.
Your breathe is fast and shallow and panic raises by the second.
Fuckfuckfuckfuckfuck—
Your nails rake against tile beneath the thin layer of grit.
Your body slides toward the water with humiliating ease.
Fear floods your throat.
Cold and clean.
It makes your mouth go dry.
He pulls you into the water.
The shock is immediate, water up your calves, thighs, then your hips.
The cold clamps down, stealing breath.
You gasp despite yourself, and he tightens his grip to keep you from thrashing free.
You think, brutally,
*This is it.
This is how I die.*
Not because he’s tugging you under — your head is still above water — but because the shift in environment changes everything.
On land you have your rules, you have walls and traction and air.
In water, he is the rules.
He drags you deeper with the same patient pull, guiding you away from the shore where you could stand and run.
Your hands slap at the water, trying to swim backward without knowing how, and the motion is pathetic compared to his. Desperate.
You feel your heartbeat in your ears, too loud, too fast, as if your body is trying to warn itself.
He reaches the far end of the tank, where the depth increases and the light dims.
He stops there, and for a moment you hang in place, held by his grip and the buoyancy of water.
Then his other hand comes up.
It slides to your waist.
You stiffen so hard it feels like your muscles might cramp.
His fingers span your hipbones easily.
He holds you with both hands now, positioning you the way you might position a specimen for examination — head above water, torso supported, legs floating uselessly.
Your lungs drag in air in short, shaking pulls.
Your hair clings to your face, framing the expression of fear and the constant inner fight not to cry in front of an apex predator.
His face is close enough that you can see detail — the fine scars at the edge of his mouth, the way his lips are darker at the corners, the black lines of tattoo that frame his eyes and make his expression look perpetually sharpened.
His teeth show when his mouth parts.
Rows of them, not exaggerated like a monster’s, just real — triangular, serrated, built to saw through flesh.
Seeing them this close makes your stomach turn and your skin go cold despite the warmth of his hands.
He watches you react.
There is something in his gaze that isn’t simple hunger.
Curiosity, yes. Control, undeniably. And beneath that, a kind of amused contempt, like he’s always known you were fragile and this is him proving it on his terms.
You force your voice through clenched fear.
“You don’t... need to do this.”
His nostrils flare.
He draws in a slow breath, and you realize he’s smelling you the way sharks taste the water — reading chemical information, stress, sweat, the subtle shift in your body that betrays terror.
He leans closer.
Not to bite.
To inspect.
His forehead brushes near your temple, not quite touching.
His cheek passes close enough that the fine hairs on your skin lift.
He inhales again, deeper, as if committing you to memory.
Then his fingers move.
He presses a claw lightly against the inside of your wrist where your pulse jumps.
Not enough to cut, enough to make you aware of the point.
He holds it there, patient, feeling the frantic rhythm under your skin.
Your breath hitches.
His eyes narrow, and you understand with a sick twist that he’s enjoying the fact that he can feel your fear in physical measurements.
His hand shifts to your throat.
You choke on air, reflexive panic spiking.
His thumb rests at the hollow near your collarbone, the place where skin is thin and vulnerable.
Two fingers curl around the side of your neck, careful of the artery, but present enough that your body screams at you to fight.
You don’t.
Not because you don’t want to.
Because you know what would happen if you provoke him into using the strength he’s been withholding.
So you stay still.
You keep your head above water and your eyes on his face and you let yourself feel the humiliation of being held like something small and easily managed.
He studies your expression as if it’s a language.
Then, unexpectedly, his grip eases — only slightly, but enough that you realize he isn’t trying to drown you.
He is making a point.
His fingers slide to your hair, he takes a strand between claw and thumb, lifts it, lets it drift through water like kelp.
His gaze tracks the way it floats, then returns to your face, as if comparing you to the environment he knows and deciding where you fit.
His hand moves to your mouth.
He cups your jaw with the heel of his palm, fingers along your cheek. The webbing between them brushes your skin, strange and intimate.
You can feel the calluses there, the texture of something built for frictionless movement now touching a human face.
You swallow, throat bobbing under his thumb.
His eyes lock onto the motion.
For a moment, the air between you thickens with something you don’t want to name, because naming it would make you complicit in it.
*You are terrified.
You are trapped.*
And you are close enough to feel the heat of him, the solid warmth of his body radiating through water as if the cold can’t touch him.
He tilts his head slightly, like he’s considering biting, like he’s considering speaking.
When he opens his mouth, no sound comes out at first.
Just a slow exhale that ripples the water between you.
Then, rough and low, he produces a syllable.
It isn’t English, not cleanly.
It’s the shape of a sound you’ve made a hundred times in his presence, pulled through a throat that isn’t used to it.
A vibration more than a word.
Your name doesn’t exist in his mouth yet.
But your role does.
“Hu... man.” he says, mangled, almost mocking.
Your lungs seize.
Shock cuts through fear for a moment so sharply it makes you dizzy.
He watches your reaction like he’s watching a light turn on.
And then he smiles — small, sharp, all teeth and intent — and you understand that the first time he speaks is not obedience.
It’s leverage.
He keeps holding you there, steady, letting the realization sink into you the way cold seeps into bone.
He can learn.
He can choose when to show it.
He can decide what parts of himself to reveal and what parts to keep hidden until it benefits him.
You stare at him, chest rising and falling too fast, waterline trembling at your chin.
Your voice comes out thin.
“You’ve been— listening.”
His eyes don’t blink.
He shifts his grip, pulling you a fraction closer, and his claws press into the fabric of your clothes at your waist, anchoring you.
Not hurting, just claiming space.
Another sound rumbles from his chest, too low to be a laugh but close enough that the meaning lands anyway.
When he finally moves, it’s not to release you immediately.
He turns you slightly, guiding you like a swimmer guides a child, and for one horrible second you think he’s going to drag you under, into the dark end where you can’t reach air fast enough.
Instead, he brings you back — slowly — to shallower water.
He pushes you toward the shore ledge and lets you find footing in the sand.
His hands stay on you until you’re stable, until you could, in theory, run.
Only then does he let go.
You stumble backward, water streaming off you, breath coming in hard pulls.
Your legs shake.
Your hands lift as if to defend yourself, useless.
He remains in the water, half submerged, watching you with that same focused attention he’s used for weeks.
Predator.
Prisoner.
Student.
Teacher.
You back away from the edge, dripping onto tile, every nerve raw.
You don’t turn your back on him, even though the instinct to flee is screaming.
You stop only when you hit the dry sand line, when you can feel the difference beneath your feet.
He doesn’t pursue.
He doesn’t lunge.
He simply rests his hands on the shore ledge and leans there, looking at you like he’s satisfied with what he’s learned.
You manage to speak, though your voice trembles with anger and fear braided together.
“What was that.”
His eyes half-lid again, that familiar pretense of disinterest returning as if he can put it on like a coat.
But his mouth moves, slow, deliberate.
And he says, clearer this time, the consonants still rough but the meaning unmistakable.
“Now,” he murmurs, “you know.”
He slips back into deeper water with a single powerful sweep of his tail.
The current changes around him like the world rearranging itself to accommodate his body. In two breaths he’s already farther away, shadow reclaiming him.
You stand there, soaked and shaking, staring into the tank until your eyes burn.
Because he didn’t try to kill you.
He tried to teach you something.
That the House is not yours.
That the rules on paper mean nothing once you’re in his element.
That he has been watching you the same way you’ve been watching him, and he is no longer content to be the only one behind glass.
You don’t know what the scientists will say when you report this, if you report it at all.
You don’t know if the next time he decides to pull you into the water, he’ll be as careful.
You do know one thing, with a clarity that makes your stomach twist.
The experiment has changed.
And whether you like it or not, you are no longer the only one attempting communication.
ETHOGRAM ENTRY VIII — Epilogue: Selkies, Guidance and Home.
Suguru keeps calling it guided like that word makes it gentle.
It isn’t gentle, it’s controlled, it’s monitored, it’s the difference between a fire in a hearth and a fire that eats your whole house because you thought you could ignore it.
In the inlet, the days stop being counted by storms and hunger and start being counted by rules.
Sukuna learns quickly that a human body can be stubborn in ways teeth can’t solve.
You don’t become sea in one violent moment. You become sea the way stone becomes smooth — by constant pressure, by repetition, by surrendering to the only environment that will have you.
When the fevers come, they come like they’ve been waiting for a quieter place to do their work.
They don’t arrive with warning. One moment you’re sitting on warm rock with your legs submerged and your head resting against Sukuna’s forearm, half listening to Suguru talk about coastal tribes and inherited symbionts, the next your skin is too hot to bear your own touch, your throat tightens, and your limbs jerk as if your body is trying to flee itself.
Suguru’s tentacles are there before Sukuna’s temper fully wakes. He braces you, coils around your calves and thighs, keeps you on your side so you don’t choke, keeps your spine from arching hard enough to strain your throat while tissue forms.
Sukuna’s pupils blow wide every time you make a sound.
He sits over you like a storm that refuses to move, one hand at your jaw to keep you steady, the other pressed to your belly to feel how your muscles clamp and release. He doesn’t soothe you with soft words.
He doesn’t know how.
He says, “Breathe,” in a voice that makes it an order your body can obey when your mind is too exhausted to do anything but panic.
He says, “Hold,” when your fingers claw at stone.
He says, “I’ve got you,” once, rough and irritated, like he’s angry the sentence exists in his mouth.
Suguru pretends he doesn’t hear that last one. Mimiko and Nanako don’t, they grin at each other in the water and file the moment away like ammunition.
Suguru makes it practical too. He doesn’t treat your change like a miracle and he doesn’t treat it like a punishment.
He treats it like engineering.
Like guiding a current so it doesn’t carve the wrong path.
The first days after the worst fevers are quiet, mostly because you don’t have the strength to be anything else. You sleep in Sukuna’s heat, wake to swallow water wrong and cough until your eyes tear, then drink what Suguru hands you and try again.
Mimiko and Nanako circle like bright, smug little knives, always close enough to be present and always far enough that Sukuna can’t justify lashing out without looking like an animal.
They touch you a lot.
Not in a way that shames you — more like they’re mapping you.
Checking your skin temperature with the backs of their fingers, flicking water at your face to make you blink and adjust, tugging gently at your wrists to teach you how to roll with a wave instead of bracing against it.
Sukuna hates every touch that isn’t his.
He keeps his body on the rocks more than he wants, tail heavy, spine aching from the drag, just to keep you pinned into warmth and proximity. He’s learned that if he’s close enough, you breathe steadier. If he’s close enough, you stop looking like you might slip away when no one is watching.
Suguru notices and doesn’t comment — Suguru notices everything and only speaks when it matters.
“Your blood still thinks it belongs to air and land.” Suguru tells you one morning when you wake with your hands at your throat, rubbing the sore place beneath your jaw. “So we teach it otherwise.”
You look at him with dull exhaustion and some stubborn spark underneath.
“How?”
Suguru’s tentacles rise, slow and deliberate.
One coils around your waist, another around your thighs, anchoring you. He doesn’t do it to scare you, he does it because he’s learned you can’t be trusted to stay still when pain spikes. He’ moves you slowly, raising your body when another tentacle wraps around your torso, keeping your arms glued to your sides.
He makes it look like you weight nothing.
Sukuna’s claws scrape stone, he’s there like he always is nowadays, besides you.
His eyes narrow hard.
Suguru glances at him once, flat.
“We’ve been through this. Do you want her safe or do you want to posture?”
Sukuna doesn’t answer. He shifts closer until his chest brushes your shoulder, heat pressing into you like a shield.
Suguru maneuvers you skillfully and dips you into the water up to your neck.
Sukuna follows to be close, to be able to help you if you need.
Your breath catches automatically. You tense, old reflex flaring — brace, fight, rise.
“Don’t!” Mimiko says, impatient and soft at once, right beside your face. “Stop fighting it.”
Nanako floats behind you, hands under your elbows to keep you from flailing.
“Think of it like going limp in someone’s grip,” she adds, smiling like she knows exactly how that sounds. “If you lock up, you sink wrong.”
You glare weakly, but you try.
Suguru’s voice stays calm.
“When the lamellae open, you’ll want to cough. You will cough. That’s fine. What you don’t do is panic.”
Sukuna’s hand clamps your hipbone, keeping you from twisting away. His mouth is near your ear, voice low and rough.
“If you panic, I will hold you until you stop.”
It should sound like a threat — with him it always does. It also sounds like a promise.
You swallow, jaw tight, then nod once.
Suguru dips you under.
Water closes over your head and the first instinct hits like a kick — up, up, up.
Your body jerks. Suguru’s tentacles tighten, firm but not crushing. Sukuna’s grip on your hip goes iron.
You hold your breath and force your muscles to go looser.
There’s a strange pressure under your jawline, a swelling sensation that is not swelling. Tissue shifting. Something trying to open that has never opened before.
You cough underwater.
Bubbles burst from your mouth in a panicked stream.
Your eyes fly open.
For a heartbeat, everything in you screams.
Suguru’s voice comes through water like a vibration.
“Let it happen. Don’t chase the surface.”
You stop fighting long enough for your throat to do its ugly work. The cough becomes a sputter. The sputter becomes a rough, controlled expulsion. The lamellae — immature, raw — flutter open for a tiny exchange that isn’t breath the way you used to know breath, but something like it. Enough to keep your brain from tipping into full alarm.
Sukuna hauls you up immediately after, because his patience ends where your life begins.
You break the surface coughing hard, gulping air, face flushed and furious.
“Are you trying to drown me?” you rasp.
Mimiko snorts.
“You’re still talking. That’s a good sign.”
Nanako grins.
“And you didn’t pee. That’s also a good sign.”
You blink.
“What?”
Nanako shrugs, unbothered.
“Humans do that when they panic. Suguru says it’s useful data.”
Suguru doesn’t smile.
“Again later. Not now. Your body needs rest between pushes.”
You glare at him like you want to bite. Then you sag, exhaustion hitting you in a wave, and Sukuna drags you against his chest, arm locking around your waist. He presses his chin to your head and breathes out hard through his nose as if he’s angry at your weakness and relieved you’re still there.
You stay like that, clinging without thinking, while Suguru watches your throat work and your breathing settle.
It doesn’t happen in one session. It happens across days, then weeks.
In between the water work, Suguru forces you to eat like your body is building a new architecture, because it is. Fatty fish. Soft seaweed. Dense, oily things Sukuna drags up from deep and drops with a look of disgust. Suguru has you chew until your jaw aches, swallow until your stomach threatens revolt, then sleep in Sukuna’s heat until the food becomes part of you.
And slowly, your body stops feeling like it’s losing.
The first visible changes show up at your hips.
One morning you wake and your pelvis aches like you’ve been riding something for hours, the deep joint pain of bones that are being told to reorganize. You shift, hissing, and Sukuna’s eyes snap open immediately.
“What,” he demands.
“Everything hurts,” you mutter, voice thick with sleep and irritation. “My hips—”
Suguru is already there, as if he never sleeps. He crouches in the shallows, tentacles coiled lazily, eyes sharp.
“Good,” he says.
You glare.
“That’s your favorite word.”
“It’s accurate,” Suguru replies. “Your lower half is committing.”
The phrase makes your stomach flip.
Committing. Like you’re signing something with your bones.
Mimiko and Nanako float in the shallows, heads tipped together like they’re gossiping. Nanako says loudly,
“She’s molting.”
You glare weakly.
“I’m not molting.”
Mimiko’s smile is sweet in a way that means it isn’t.
“You’re changing. Your bones are shifting. Call it whatever makes you less dramatic.”
Sukuna’s eyes narrow at them.
“Stop talking.”
Nanako’s grin widens.
“Or what. You’ll sulk louder.”
Sukuna makes a low sound in his throat, the kind of sound that used to make you flinch in the facility.
Now it mostly makes you feel… held.
You can’t explain that without hating yourself a little, so you don’t.
Over the next days, your thighs change.
At first it’s only sensation — your muscles feel denser, as if they’ve thickened from the inside. Your skin on your legs starts to behave differently. Less dry. Less prone to cracking. It holds water like it wants to keep it. When you press your palm to your thigh, the skin feels slightly slicker, not slimy, just… adapted.
Then the hair changes.
You notice it when you run your hand down your shin and realize you can’t feel the fine growth the way you used to. It’s not that you go hairless, it’s that the texture shifts into something closer, finer, like short velvet that lies flat and doesn’t catch water the same way.
Mimiko grabs your ankle one afternoon and turns your foot to examine it, eyes bright with curiosity.
“You’re getting flipper-soft,” she chirps.
You try to yank away.
“That sounds disgusting.”
Nanako laughs.
“It sounds correct.”
Sukuna’s hand closes around your other ankle in a possessive counter, holding you steady while Mimiko inspects. His pupils are narrow now, not blown with hunger, but his attention is sharp and irritated.
“She is not a toy.” he growls.
Mimiko looks at him, unimpressed.
“Neither are you.”
Nanako adds, sweet as poison.
“But you still get played with.”
Sukuna’s lip lifts. His claws flex.
Suguru’s tentacle taps Sukuna’s forearm like a reprimand.
“Focus. If you scare them off, she loses teachers.”
Sukuna hates that sentence.
He hates that it’s true.
He holds still, jaw tight, and lets Mimiko finish her inspection.
The first structural change happens at your feet.
It’s not sudden.
It’s progressive, horrifying in how methodical it is.
Your toes start to feel… less independent.
The sensation of separating them, wiggling them individually, becomes dull. The joints feel thicker. When you walk on rock, you start to hate it because the shape of your foot is subtly wrong — pressure points shifting. Your arches ache. Your ankles feel heavier. The ache in your hips deepens into something that feels like pressure in the joints, like your bones are grinding and smoothing, grinding and smoothing, trying to find a new alignment. Your knees ache when you bend them. Your ankles ache when you try to stand. You start moving more in the water because land feels increasingly… unhelpful.
Suguru stops letting you walk as much.
“You’re not meant for stone anymore.” he says, blunt.
That sentence should terrify you, but it lands with a strange, exhausted relief. You’ve been fighting land since the day you escaped. Your body has been losing that fight with every storm and every cracked lip and every hollowed-out night.
So you stop walking, and you let the sea take more of your time.
Sukuna carries you more without comment.
He does it the way he does everything — without asking, without softness in his face, as if your weight is an inconvenience he’s decided to tolerate. He hooks an arm under your thighs and drags you into the water, keeps you flush to his torso as he moves so you don’t burn in the sun and don’t bruise your changing feet on rock.
Sometimes you rest your head against his shoulder and close your eyes, listening to the steady beat of his movements.
He never tells you to stop. He never tells you it’s too much. He simply holds you like it’s his job.
When the feet finally begin to fuse, you feel it before you see it.
One morning you wake and your feet feel wrong.
Not numb. Not dead. Wrong.
It starts as a webbing sensation between your toes — skin tightening, stretching, as if the spaces are being filled.
Your toes don’t spread like they used to. The webbing between them is thicker, more pronounced, and when you flex, you feel resistance where there used to be air and skin.
You stare at your feet and swallow.
Sukuna is watching from the rock beside you, upper body out of the water, forearms braced. He has been doing that more lately — staying on rock longer than he likes, just to keep you within reach.
You lift your foot slightly, flexing.
“It’s happening.”
Sukuna’s jaw tightens
“Yes.”
“You’re not surprised?”
He snorts.
“I’m not blind.”
Suguru surfaces behind you, calm.
“Good,” he says. “That means your body chose flipper formation rather than clinging to individual toes.”
You repeat, squinting.
“Chose.”
Suguru’s mouth curves.
“It’s not conscious choice. It’s adaptation. Your body prefers what keeps you alive.”
Nanako swims closer and peers at your feet with open delight.
“Cute,” she declares.
Mimiko, dry as ever,
“Don’t get attached to them.”
After that, your toes are not toes anymore.
They are joined by smooth webbing, the outline of digits still visible beneath the skin, but the spaces are gone. Your foot looks broader. The heel is thicker. The ankle joint looks slightly reinforced.
Nanako hums, pleased.
“Pretty.”
You stare, half horrified.
“That’s… uh, not my foot.” it’s all you manage.
Mimiko bumps your shoulder lightly with her own.
“Not anymore. Get used to it.”
And you do.
The lower half change accelerates after the feet.
Your calves thicken subtly, then lengthen into a shape that is less leg and more powerful taper. Your knees stop feeling like hinge points meant for walking. They become internal, less prominent, like the joints are repositioning for propulsion rather than stepping.
Your skin changes texture further — dense, sleek, with that fine, close coat that lies flat in water. The color comes in gradually too, a darker tone across the outer edges, lighter along the inside, faint speckling that makes your lower half look like it belongs to an animal built to disappear in shifting light.
You lose the human silhouette below the waist piece by piece.
Your thighs widen into a smooth torpedo shape, hips rounding with a layer of insulation you never had before.
Suguru calls it necessary.
Mimiko calls it cute.
Nanako calls it finally, you won’t freeze like an idiot.
Sukuna watches the fat settle on you with a strange, tight expression. He’s seen you starving, he’s seen your ribs too sharp. Seeing your body claim warmth again, claim endurance, triggers something in him that feels like relief and possession mixed into one.
He touches you more as you change.
Not sexually, not indulgently — checking, assessing. His claws trace the line where your human skin meets the new sleek texture, he presses his palm to your lower back, feeling the warmth you retain now. He holds your ankles — your flippers — between his hands and flexes them gently, testing range the way he used to test your wrists when you were weak from fever.
You let him, because his touch has become a language you understand — I’m here. You’re mine. You’re still alive.
When the hind flippers finally form, it happens during a night of fever you almost handle quietly.
Your lower half aches so hard you can’t sleep.
You float in the shallows, Sukuna holding you upright, chin braced against your shoulder. The water is warm enough that you don’t shake. Your throat feels thick but functional, you can exchange a little bit more underwater now, not perfectly, but enough that you don’t immediately panic.
Suguru appears like he always does when things reach a critical point.
“Tonight.” he says.
You blink slowly.
“What’s tonight?”
“The final structural shift,” Suguru answers. “If you fight, it will take longer and hurt worse.”
“The tail—” he corrects himself immediately, because you’re not a fish and he knows it, “—the hind flippers. The pelvis finishes. The legs commit fully. She’ll want to curl. She’ll want to kick. We keep her still.”
Sukuna’s jaw tightens.
“I will.”
It starts like an itch that isn’t itch.
You want to scratch and can’t find relief because the nerves are rewriting themselves.
You whine once, low in your throat, and Sukuna’s entire body goes rigid.
Suguru’s tentacles rise.
He wraps them around your lower half in a careful, firm cradle, suction cups anchoring without bruising. He keeps you in water because water will carry you through pain better than rock. He keeps the restrain tight to keep you from clawing at your own skin.
You plead, breathless.
“It burns.”
Sukuna’s eyes flare, the urge to tear Suguru away surging hard. He sees your face twisted with discomfort, sees your fingers flexing like you want to rip yourself apart, and his vision goes narrow.
Suguru doesn’t flinch.
“This is where humans ruin it,” he says, calm and cold. “They scratch, they tear, they introduce infection. They panic and fight the body’s work. You will not.”
Sukuna’s fists clench, his jaw tightens, he leans over you, pressing heat into you until your shaking eases.
“Hold still.” Sukuna orders, rough.
You stare at him, eyes wet, not crying so much as overwhelmed.
“I’m trying.”
He presses his mouth to your forehead — firm, grounding, not gentle enough to be tenderness — and growls,
“Try harder.”
It’s cruel.
It’s also the only language he knows to keep you from slipping.
Your calves and thighs begin to feel like they’re being pulled.
Not ripped — drawn.
The muscles rearrange. The bones feel like they’re softening, shifting, fusing in places your brain insists they shouldn’t.
You cry once from frustration and pain, face pressed into Sukuna’s forearm while he holds you still and growls at the sky like it’s responsible.
Suguru’s tentacles keep restraining you through the worst of it.
He doesn’t let you thrash.
He doesn’t let you tear yourself against rock or sea.
Sukuna watches looks like he’s about to commit to violence just to have somewhere to put the feeling.
When you whimper his name, It’s low, involuntary, the sound is thin, he leans down and presses his mouth to your hair, breath hot, arm tight around your ribs.
“Look at me.” he orders.
You manage to turn your head.
Your eyes meet his — crimson rim, dark center, attention sharp enough to pin you.
“I’m here.” you whisper, voice ragged.
He presses his forehead briefly to yours, then pulls back enough to watch your face.
“Stay,” he growls.
The pain hits in waves — deep joint ache, then a twisting pressure, then a burning sensation along the back of your thighs as tissue folds and reshapes.
You try to jerk.
Suguru’s tentacles hold.
Sukuna holds harder, heat and strength wrapped around your upper body like armor.
Your pleas come out broken, half words, half sounds. You don’t mean to make them, your body is simply loud.
Sukuna sees red.
Not at you, at the process.
At the idea that this is the price of saving you.
He restrains himself so hard his whole frame trembles.
When it’s done, you don’t realize immediately.
You simply sag, exhausted, and your breathing steadies in the water like you’re finally compatible with it. Sukuna keeps you close.
When the pain subsides, Suguru loosens the tentacles and lets you look.
Mimiko and Nanako hover close, curious and excited despite themselves.
Your legs are no longer legs.
The last traces of human leg are gone, folded into a shape that makes sense in the sea.
You stare, stunned, chest rising fast.
From the waist down you are a sleek, powerful body built for water, hips broad with insulation, hind flippers fanned at the end like strong, dark hands made for propulsion.
They’re there, okay, — still length, still structure — but they’re drawn into a new shape, thighs thickening, knees less defined, lower legs shortening subtly. The webbing at your feet has expanded into broad, strong flippers that don’t look human at all. Your ankles have become a smoother line. Your calves no longer taper the same way. Your lower half is built for water, not walking.
You touch your flipper with trembling fingers.
The skin is different.
Sleeker. Slightly thicker.
When you press, there’s new softness under it — a beginning layer of fat that holds warmth.
You swallow hard, tears stinging.
“I can’t— I can’t walk like this.”
Suguru’s voice is calm.
“You won’t. Not much. Seals can haul. They can pull themselves over rock. But your home will be water.”
Sukuna’s grip tightens around your waist. He says nothing for a moment.
Then, rough, “Good.”
It should irritate you.
It doesn’t. Because there’s relief tangled in the word, and you feel it like a thread tying you to him.
Mimiko and Nanako surface near you, eyes bright.
Nanako whistles softly.
“You’re beautiful.”
You swallow, throat tight.
“I’m…”
Mimiko’s voice is steady.
“You’re you.”
Suguru’s tone stays practical.
“You’re alive. That was the point.”
Sukuna doesn’t say anything. His arm tightens around you like he wants to crush you into his chest and keep you there, away from eyes, away from danger, away from the possibility that the sea could still take you despite all this.
You reach back without thinking and grip his forearm.
He looks down at your hand, then at your face.
“You live.” he says, rough.
You nod, overwhelmed.
“I think— yes.”
Nanako drifts closer, eyes bright.
“Seal legs are better anyway. Fast. Strong. Cute.”
Mimiko adds, deadpan,
“And you can bite people.”
You blink, then frown.
“I can bite people now?”
Sukuna’s mouth curls, pleased in a way that’s immediately irritating.
“You already bite.”
Heat crawls up your face. Mimiko and Nanako exchange a look and grin like they’ve been handed a gift.
Suguru clears his throat like he’s done with you all.
“Tomorrow,” he says, “we start adapting movement. In the water.”
You glance at the sea, then at Sukuna. The old fear prickles — panic reflexes, choking, the memory of coughing underwater.
Sukuna’s gaze holds yours.
“You wanted this,” he says, low.
“I still do.”
“Then go.”
It sounds like permission. It also sounds like a challenge.
You learn how to move.
It’s humiliating at first.
On rock, you have to pull yourself with your arms, dragging your lower half behind you.
Mimiko and Nanako laugh — kindly enough not to cut, cruelly enough to keep you from drowning in self-pity.
“Arms,” Mimiko instructs. “Use your arms. Stop trying to stand.”
Nanako adds, delighted,
“You look like a dramatic sea sausage.”
Sukuna growls at them.
“Shut up.”
They grin wider.
Suguru guides you in the shallows with a tentacle braced under the soft hinge of your tail and another under your ribs.
The water laps at your waist, then your chest. Your hips ache when buoyancy takes weight off them, and you realize how much your body has been fighting gravity.
Sukuna stays close, half submerged, hand hovering near your shoulder without touching, as if he’s trying to respect Suguru’s method while still refusing to be more than an arm’s length away.
Mimiko and Nanako circle, eager and impatient.
“Kick,” Nanako says.
“I— I know how to swim,” you protest.
Mimiko’s eyes narrow.
“Not like this.”
Suguru’s tentacle presses at your lower back, guiding the angle.
“Don’t fight the water,” he says. “Let it carry you. Your hips will learn.”
You try. Your body wobbles. You sputter when a wave hits your mouth unexpectedly.
Sukuna’s hand clamps your upper arm immediately, keeping you from jerking backward. His voice cuts through the panic like a blade.
“Enough.”
You inhale hard through your nose. You force your shoulders to loosen. You float.
Mimiko hums, pleased.
“Good.”
Nanako darts forward and flicks your seal tail with her eel tail.
You yelp, reflexive, and sputter again.
Sukuna’s snarl is instant.
“Touch her again and I’ll rip you in half.”
Nanako laughs in your face.
“He loves you.”
Sukuna’s eyes flash. Mimiko, smug, adds,
“He’s going to kill someone before you’re done becoming.”
Suguru’s tentacles tighten around your midsection, steadying you.
“He can kill someone after,” he says dryly. “Right now he can learn patience.”
Sukuna looks like he would rather chew rock.
Each success is small. Each one is earned with discomfort.
You learn to move in water with the new shape. At first you kick wrong, the old muscle memory trying to flex toes that don’t separate. Then Suguru has you stop trying to kick like a human and start moving like something built for it — hips rolling, thighs driving, the fused shape pushing water in wider, more efficient strokes.
Your flippers push against the current with a strength that surprises you when you finally learn. When you angle your hips and kick, you glide.
Your body feels… correct in the water. You’re still clumsy, still learning, but you’re no longer fighting the sea. You’re starting to belong to it.
When you finally manage a clean glide, the first time you move without flailing, you surface laughing — real laughter, bright and startled.
Sukuna watches you with a look he tries to keep hard. His eyes track you like you might break and vanish. His mouth stays set, but something in his posture loosens by a fraction.
Mimiko claps water at Sukuna’s face.
“She’s swimming.”
Sukuna’s gaze snaps to her.
“I can see.”
Nanako grins.
“You look relieved.”
Sukuna snarls.
“I look like I always do.”
Suguru’s eyes flick between them, amused.
“You look like you’re trying not to.”
Sukuna doesn't lose the opportunity to haul you in whenever you're near him.
He presses his mouth briefly to your temple again when you're done for the day and with your midsection wrapped by his arm — his way of affection, you learned.
Then he turns his glare on Suguru.
“If she gets fever again—”
Suguru lifts a brow.
“She will. But it will be different now. The body isn’t arguing the same way, saltblood is settled.”
Suguru is right.
The fevers still come for a while, but they don’t feel like your body is trying to kill itself. They feel like adjustments. Your appetite steadies. Your energy returns in small increments. Your throat’s lamellae mature enough that you can spend longer underwater without the panic spike, and when you cough, you recover faster.
You start laughing again.
You start exploring with Mimiko and Nanako like a hungry thing.
They drag you through kelp forests and show you how to hide between fronds when currents run cold. They teach you how to eat without cooking, and underwater — how to choose safe flesh, how to avoid parasites, how to recognize the wrong smell. They show you reef pockets where coral glows in colors that feel too vivid to be real, and you watch with awe that doesn’t need words.
All the while, they pester Sukuna.
They call him old. They call him clingy. They tell him he looks like he’s guarding a treasure and doesn’t know what to do with it.
Sukuna’s responses are predictably ugly.
He threatens. He snarls. He swims closer and crowds them in water until they dart away laughing, eel bodies slipping through gaps his bulk can’t follow.
He never actually hurts them.
You notice that too.
Suguru teaches you breath next.
He makes you dip under in controlled bursts, his tentacles holding you steady, his voice a calm thread in your mind when panic threatens. He teaches you to swallow underwater without choking, to let lamellae open and close, to recognize the sensation — tightness under the jaw, a faint fluttering in the tissue, a cool exchange you feel more than you understand.
The first time you manage ten seconds underwater without needing Sukuna’s mouth or hand, you come up with a laugh that sounds shocked.
“I did it!” you breathe.
Nanako claps her hands. Mimiko nods, approving in her restrained way.
Sukuna’s gaze stays on your face like he’s memorizing the expression. He looks… relieved. It makes him look strange.
Suguru’s tentacle taps your jawline.
“Good. Again later. Don’t get cocky.”
You glare at him.
“You’re awful.”
Suguru’s mouth curves.
“You’re alive. That’s my job.”
Sukuna’s protectiveness shifts as you change.
It stops being only hovering and growling and refusing to let anyone touch you. He starts doing things without being asked, practical and territorial.
He brings you food before you realize you’re hungry. Not just fish — fatty, oily ones, things that help your changing body and make your body feel satisfied in a way it hasn’t since the facility.
He catches them and drags them to you with a look like the act is beneath him, then watches you eat as if guarding you from your own tendency to stop when you’re tired.
He positions himself between you and strangers without thinking.
When merfolk pass through the inlet, curious eyes flicking toward you, Sukuna rises higher on the rock and lets his presence speak for itself.
Mine.
Mimiko and Nanako find endless delight in needling him about it.
“He’s nesting,” Mimiko says one day, voice loud enough for him to hear.
Nanako giggles.
“He’s brooding like a pregnant—”
Sukuna’s head snaps toward them, murderous.
Nanako laughs harder.
“Oh, that one hit.”
You flush for reasons that have nothing to do with the sun. The memory of what happened between you and Sukuna — twice, now — sits in your body like a secret you don’t know how to interpret.
The way he described his anatomy back then before demanding to explore yours, the way he’d been smug, the way you’d been ovulating without knowing it mattered… it all feels distant and close at once.
Sukuna’s gaze flicks to you briefly, as if he senses the thought.
His expression tightens.
He says nothing.
Suguru watches both of you and, for once, doesn’t comment.
When saltblood finally settles, it doesn’t announce itself with a dramatic moment.
It’s quieter.
You wake one morning and realize you aren’t afraid of the water in your lungs anymore.
Not because you want to inhale water — you don’t — but because the reflex that screams death has softened. You can submerge and let your body exchange in small, controlled ways without panic swallowing your mind.
Your skin holds warmth better. The sun doesn’t burn you as fast. The cold currents don’t slice as deeply. Your hunger is steady and meaningful instead of desperate.
Your body feels… built.
Built for this.
Suguru checks you with the same clinical focus he always has, tentacles feeling your jawline, your throat, your pulse. Then he nods once, satisfied.
“You’re taken,” he says.
The word makes your chest tighten.
Mimiko’s smile softens, genuine this time. Nanako’s eyes brighten like she’s proud.
Sukuna goes still, pupils wide, and something in his face looks like he’s bracing for loss even as he gains you.
You lean into his side without thinking, cheek against his shoulder.
“I’m still me,” you murmur.
Sukuna’s arm locks around your waist immediately, firm.
“I know.”
His voice is rough like he had to scrape the words out.
Suguru teaches you language the same way he teaches you breath — slowly, with no pity.
He shows you how merfolk shape sound underwater — not with human throat mechanics, but with altered resonance, with the new structures in your neck and mouth learning to work with water rather than against it.
You practice simple syllables. You mimic. You fail.
You try again until the shape stops feeling foreign.
You don’t speak their language yet. Not truly. But you can make the sounds now!
You can hold them without choking, and that alone feels like stepping into a room that used to be locked.
Suguru claps his hands once, like breaking a spell. “Good. Then it’s time you meet the rest.”
He doesn’t give you a chance to overthink it.
He leads you out of the inlet, Mimiko and Nanako flanking you like eager guards. Sukuna stays close behind, close enough that you feel his wake in the water. He doesn’t let you drift too far ahead. He doesn’t let you fall behind.
The first gathering you see isn’t a formal council. It’s simply… merfolk living.
They cluster near a reef edge where the current brings food and gossip. Bodies move through water with ease, different tails and forms — sleek fish-like lower halves, thick mammal forms, long ribboned shapes that make you think of eels and rays. Their upper bodies vary too: some more human, some more scaled, some with webbing and fins that flutter at their ribs.
Most of them stare at you.
Not hostile. Not welcoming. Curious. Measuring.
You feel suddenly naked, despite being in water.
Sukuna rises behind you like a wall. His presence shifts the whole group’s attention. Conversations — strange clicking and vowels you can’t reproduce yet — pause.
Eyes slide to him. Many look away quickly. Some hold his gaze with wary respect.
One figure moves forward with calm assurance, pale-haired, composed, eyes sharp. Their posture holds none of the flinching fear others show. They stop at a respectful distance and incline their head slightly toward Sukuna.
Sukuna’s expression doesn’t soften, but his attention sharpens. Like recognizing someone who matters.
You swim closer, cautious.
Suguru murmurs near your shoulder,
“Uraume.”
You look at him.
“That’s their name?”
Suguru nods.
“They’re old enough to remember when Sukuna was only rumor. They respect him. Not because they like him. Because they’ve seen what happens when you don’t.”
Uraume’s gaze flicks to you. They don’t smile. They don’t sneer. They simply look, and the look feels like being assessed by someone who values survival over sentiment.
They speak, and the language rolls through water in shapes you can’t mimic yet — clicks and low tones, a throat-sound that makes your jaw ache in sympathy.
Your new organs — lamellae, altered throat tissue — recognize the shapes even if your mind doesn’t. You can feel the potential to reproduce them, like your body is saying later.
Suguru answers in the same language, fluid and practiced. His voice shifts in ways that make it clear he’s spent years learning how to be understood here.
Uraume responds, gaze never leaving you for long.
Sukuna speaks once — short, rough, and clearly not as fluent as Suguru but far from the blunt beginnings you remember in the facility. The merfolk around you react subtly, a ripple of attention, a shift of posture.
Mimiko leans in and whispers in English, gleeful,
“He’s introducing you.”
Nanako adds,
“He sounds like he’s threatening them into being nice.”
Sukuna’s head snaps toward them with a glare that could curdle water.
They grin wider.
Suguru turns to you, voice quieter.
“They’re asking what you are.”
You swallow, throat working.
“Tell them… I’m becoming. I’m not here to hurt anyone. I just… want to live.”
Suguru relays it, voice smooth.
Uraume watches you for a long moment. Then they speak again, slower this time, and you catch a few sounds Suguru has been repeating in lessons — basic syllables, a simplified phrasing used when teaching language to someone new.
It’s still not English. It’s still not fully understandable. But the intent is clear enough, a cautious acknowledgement.
They glance at Sukuna again, and the respect is real.
Not affection, not friendship. Respect built on knowledge.
You realize, with a small jolt, that your life in the sea will always be tied to Sukuna’s shadow.
Some will keep distance because of him. Some will test you because of him. Some will watch you to see if you’re prey he claimed or a person who chose.
The weight of it settles in your chest.
You recognize only fragments of the other conversations happening — sounds you’ve practiced.
Human. Saltblood. Chosen. Not prey.
The last part you recognize because Mimiko taught you the term with a grin.
Uraume’s gaze shifts to you again. It’s not friendly. It’s not hostile either. It’s… assessing.
They speak again, slower this time, and you catch a word you recognize because Suguru drilled it into you — becoming.
You nod, awkward, then manage a rough version of a greeting in their language.
The sound comes out clumsy, but it comes out.
Uraume’s eyes narrow slightly. Not displeased. Interested.
They glance at Sukuna again and say something that makes Mimiko snort.
Nanako leans in with a grin.
“They said you’re brave or stupid,” she translates cheerfully. “It’s unclear which.”
You huff, embarrassed. Sukuna’s hand closes around your wrist, possessive and steady.
Uraume watches the gesture, then looks away as if it’s expected.
As the gathering continues, you meet more merfolk in fragments.
Most don’t speak English at all.
They speak to Suguru, not to you, their language flowing fast and confident. Some know a few English words — rough, learned, often misused.
You hear human, water, salt, Sukuna said in awkward accents. You hear your own name attempted once, butchered into something else.
A young merfolk with bright eyes tries to say “hello” and then dissolves into laughter when the sound comes out wrong. You laugh too, surprised by how light it feels.
Suguru watches you with quiet approval.
Sukuna’s hand brushes your lower back — firm, possessive, grounding.
He doesn’t say anything.
He doesn’t have to.
Other merfolk edge closer, curiosity winning over wariness. Some speak a few broken words with you, learned from Suguru, and the accent is thick, the grammar odd, but the effort is there.
“Human,” one says, then pauses, frowning, as if reconsidering. “Not… human.”
You manage a shaky smile.
“Not anymore.”
They stare at your seal lower half, at your flippers, at the way you hold yourself in water — still cautious, still learning, but no longer flailing.
Suguru keeps watching the interactions, his face holds a calm satisfaction.
“They’ll get used to you,” he murmurs. “Some will never care. Some will always be curious. But curiosity is better than knives.”
You look at him, grateful.
“Thank you.”
Suguru’s expression softens slightly.
“If you need anything,” he says, “you come to me. Any time. Fever returns, panic returns, language frustrates you, if he—” his gaze flicks to Sukuna’s looming presence, “—gets too possessive.”
Sukuna growls softly.
You nod, earnest.
“I will.”
Nanako beams. Mimiko pretends she isn’t pleased.
You manage a tired smile at them.
Suguru nods once, satisfied, then turns away to speak with Mimiko and Nanako, who cling to him like adopted daughters and act like they’ve never seen Sukuna in their lives just to annoy him.
Sukuna looks away like he’s annoyed by the whole exchange.
Then he shifts closer and says, blunt,
“We’re leaving.”
You blink. “Now?”
“Yes.”
Mimiko raises a brow.
“He’s stealing you.”
Sukuna’s gaze flashes.
“I’m taking her home.”
Nanako’s grin turns wicked.
“He said home.”
Sukuna snarls softly.
“Shut up.”
You can’t help it — you laugh. It’s small, surprised, and it feels good to have laughter that isn’t only exhaustion.
Sukuna’s attention snaps to your laugh, and for a second his expression looks… almost startled. Then he recovers, scowling as if joy is suspicious.
He guides you away from the reef with a firm hand at your back, steering you through kelp corridors and darker water.
The farther you go, the quieter it gets. The more the sea feels like it belongs to him.
He takes you farther than you expected, away from the social clusters, away from Suguru’s territory, away from eel laughter and curious eyes. The water deepens. The light changes. The ocean becomes quieter in that way it gets when you leave the shallow spectacle behind.
He moves with confidence, and now you can keep up.
Not perfectly, definitely not effortlessly, but you don’t feel like dead weight anymore. Your seal half drives you forward with strong strokes, your throat accepts the water without panic, your lungs don’t scream at you the way they used to.
Sukuna glances back once, making sure you’re there. His eyes narrow as if checking for weakness. Then he turns and swims faster, and you follow, heart beating hard with something like exhilaration.
He brings you to a place that doesn’t look like much from the outside — a jagged split in a rock wall below a shelf of coral, shadowed, hidden by a curtain of drifting kelp. The entrance is narrow enough that it feels like a throat, and your body’s reflex tries to spike with claustrophobia.
Sukuna’s hand clamps your wrist.
“Follow.”
You do.
Inside, the cave opens into a pocket of space shaped by current and time. The water is calmer here, held. The ceiling dips and rises, forming a sheltered dome. There are smooth stone shelves, patches of sand that have settled in corners, bits of drift and seaweed arranged in a way that looks accidental until you realize it isn’t.
This is a place someone lives.
Sukuna moves through it with familiarity. He brushes past a shelf and a cluster of small shells tumble softly, making a faint sound.
He looks irritated by the noise, as if even his own home shouldn’t dare announce him.
You hover uncertainly, flippers treading gently.
Sukuna turns, eyes narrowing.
“You’re tense.”
“I’m… in your cave.”
“Yes.”
“You live here.”
“Yes.”
It feels like stepping into someone’s bedroom. Like crossing a boundary.
Sukuna reaches out, grabs your waist, and pulls you closer without asking permission. His grip is firm, not cruel. It’s his way of shutting down your overthinking.
“You’re here,” he says. “That’s enough.”
Your throat tightens.
“You’re not… going to leave me somewhere else?”
You thought about it — where would you live after the becoming?
Sukuna’s eyes flash, offended.
“Why would I.”
“Because… you have the ocean now. You're back home. I'm... stable, I won't die. You don’t need me to survive.”
His jaw tightens.
“I didn’t need you before.”
The honesty stings.
Then he adds, rough, quieter,
“Now I want you.”
It’s not romantic.
It’s not gentle.
It’s blunt possession and blunt truth, and it hits you harder than soft words ever could.
You swallow.
“Okay.”
He shifts you toward a smoother sand shelf and presses you down onto it with a hand at your shoulder. The sand puffs faintly around you, cool and soft compared to rock. Your seal body settles easily in the water, buoyant, heavy in a way that feels right.
You take a slow breath.
The sensation is strange when you're quiet enough to pay attention to the exchange between water and oxygen — cool, invasive, then… manageable. Your throat tightens, then relaxes. The lamellae flutter open, not fully, but enough. The exchange happens in small, controlled pulses. You don’t choke. You don’t panic.
You blink, surprised after actually feeling, quietly, that odd sensation, and a laugh bubbles out of you — silent underwater, just a shake of your shoulders.
Sukuna watches, expression tight with something that might be relief.
You try to settle, to sleep.
Sukuna disagrees.
He moves in behind you, heavy and insistent, and curls around you the way he did in the cove — arm over your waist, torso pressed to your back, tail and shark half bracing to form a barrier. You’re not cold. You don’t need the warmth the same way anymore.
He still pulls you in as if your body is something he has to keep contained.
“You don’t have to—” you start.
His grip tightens.
“Yes.”
You blink, then let yourself relax into him, because arguing costs energy and because, if you’re honest, his hold still feels like safety.
He rests his chin near your shoulder, breath steady. You feel the vibration of him more than you hear it, a low sound like a satisfied growl that he would deny if anyone asked.
Your mind waits for panic. It doesn’t come. The cave is quiet. The current is gentle. Sukuna’s body is a wall behind you.
You drift.
Sleep underwater isn’t like sleep on land. It’s lighter, threaded with awareness, your body half listening for the wrong pressure or the wrong current. You wake once with a jolt, throat tightening, and Sukuna’s arm clamps harder immediately, a possessive reflex.
“You’re fine,” he rumbles, and the words are more for him than for you.
You breathe again, slow. The lamellae open. The exchange steadies.
You don’t drown.
When you finally settle into deeper sleep, Sukuna stays curled around you, firm and kept, as if your new body and your new life still need his claim to make them real.
And in the quiet of his cave — your first night fully taken by the sea — your lungs learn a new rhythm, your skin holds warmth like it was built for it, and your mind starts, bit by bit, to accept that you didn’t lose everything.
You changed.
You lived.
And Sukuna, who was made for loneliness, keeps you close like he’s decided he doesn’t want it back.
For those wondering how our favorite marine biologist's tail turned out to be, it's like this:
ETHOGRAM ENTRY II — Month 6–14: Speech Emergence, Trust as Method
You don’t sleep the night he pulls you in.
Not properly at least.
You rinse the tank water off in the shower until your skin stings, then sit on the edge of the bed with a towel around your shoulders and stare at the glass wall like it might blink.
The land side is dim, lit by the emergency strip along the baseboard, the water side is that false midnight blue they keep so the cameras — if they ever install them — can see.
He’s there and he isn’t there, a bulk of pale-pink-gray in the distance that your eyes keep trying to turn into certainty.
When you finally lie down, you do it like you’re negotiating with your own nerves — on your side, knees drawn up, face turned toward the tank despite every instinct that says not to offer your throat to something built to read pulse.
You listen to the pumps.
You listen for the slap of his tail against glass.
You listen for the wet scrape of claws on the shore ledge.
Nothing dramatic happens.
That’s part of what makes it worse.
The House keeps breathing on its artificial tide.
The generator keeps humming.
Your body refuses to forget his hand around your ankle, the warmth of it, the control.
Morning comes with a thin light behind clouds.
Your first thought is stupidly procedural — Log it.
Your second is bitter — If I log it, they’ll come in with restraints and needles and someone will decide the solution for the behavior is pain.
So you make coffee with hands that tremble only a little, and you open your notebook and you write in your own shorthand, the kind you learned in undergrad when you didn’t want lab partners to steal your observations.
Unprompted contact. No injury. First intelligible phoneme: “human.” Timing deliberate. Contact appears exploratory, dominance display.
You stare at the words until your eyes blur.
Then you write a second line, smaller.
He waited until I believed he wouldn’t.
At feeding, he surfaces earlier than usual. He doesn’t rush the crate this time, he drifts near the shore ledge and rests there with his torso out, water sliding off his tattoos in slow trails.
His mouth opens just enough that you can see teeth and the soft movement of his tongue as he breathes.
You keep your distance.
You don’t sit with your feet at the edge.
You stand further up the sand line where tile begins, arms folded tight enough to hold yourself together.
“You made your point.” you tell him, because silence feels like permission.
His eyes track you with the same steady attention as yesterday.
There’s no apology in his face, not even the hint of one.
He speaks again, rougher than you expect for a second attempt.
“Point.” he echoes, like he’s tasting the shape of it.
It hits you low in the gut, not in a romantic kind of way, in the way any proof of intelligence changes the air.
You swallow.
“Yes. That. You... you can understand.”
He watches your mouth when you say it.
Then he tilts his head, slow, and his lips move again.
“Understand.”
The consonants scrape out of him like they have to be negotiated past instincts meant for biting and tearing.
The word isn’t perfect, but it’s close enough that your skin prickles.
You take a careful step back anyway, not because you want distance, but because you need to remind him you still exist outside the water.
He doesn’t lunge nor grin.
He simply settles his forearms on the sand, claws sunk into the grit like anchor points.
When the hatch opens and the crate lowers, he doesn’t look at it right away.
He keeps looking at you, as if making you witness the choice to delay feeding is its own kind of power.
Then he turns and tears the seals apart with practiced ease, and the water blooms pink in slow spirals.
You force yourself to breathe evenly.
You force your hands to move.
The tape recorder stays off.
You write, because you have to put this somewhere that isn’t only your body.
After he eats, he doesn’t disappear.
He remains on the ledge, chest rising with slow, heavy breaths, eyes half-lidded like he’s sunning himself even though the overhead lights are clinical and mean.
He looks, for a moment, almost restful.
Then his gaze slides up again, pins you, and he says, quietly, as if it’s a joke he expects you to be smart enough to catch.
“Talk.”
Your jaw tightens.
“You don’t get to order me around.”
A small movement at the corner of his mouth — an almost-smile that shows too much tooth to be friendly.
“Do.”
The audacity would be funny if you weren’t living in his enclosure.
You exhale through your nose and let your anger turn into something usable.
“Fine. But we’re doing this my way.”
His eyes narrow, interested in the defiance.
You go to the desk and drag out the waterproof board and marker.
You don’t stand at the edge.
You sit where the sand starts to slope, far enough that his hands can’t reach without effort, and you write large block letters.
HUMAN.
You tap the word. Tap your own chest.
“Human.”
His gaze follows the marker tip.
He doesn’t repeat it this time.
He already owns that one.
You write.
WATER.
You point to the tank.
He shifts slightly, the shark half beneath him moving in the water like a sleeping engine.
You write.
NAME.
You tap the word and then gesture between you and him, a simple exchange offered like a truce.
His eyes go very still.
For a heartbeat you think you’ve pushed too hard, too fast, that he’ll decide the lesson is insolence and the correction is teeth.
Instead, his hand lifts.
He drags one claw through the wet sand beside him.
Three strokes.
A curve. Another line.
Not random.
Deliberate, practiced.
The shape isn’t English.
It’s a mark, a character, a symbol that means something to him.
He looks at you as if daring you to pretend you don’t understand what he’s offering.
Your throat tightens.
“That’s your name?”
He pauses, then makes the mark again, cleaner.
He taps it once with the tip of his claw.
“Mine.” he says.
The possessiveness in the word is almost tender if you don’t think about it too hard.
You nod slowly and copy the mark onto your board. Your hand shakes a little.
“I don’t know how to pronounce it.”
He watches you attempt it, then huffs a sound that could be contempt or amusement.
He drags his claw again, slower, and this time he adds something else — Roman letters, awkward at first, then steadier as if he’s seen them enough in your notes and labels to understand their purpose.
S U K U N A.
The letters are scratched into sand like a threat and a signature at once.
You stare.
He lifts his eyes to you, expression unreadable in that infuriating way of his, and says, more clearly than he has any right to this early in the process.
“Sukuna.”
The name settles in your chest.
It doesn’t fit the sterile labels in the binders.
It doesn’t fit “Specimen C-3.”
It’s too sharp, too specific, too owned.
You swallow.
“Sukuna.”
His gaze flicks over your face, measuring how it changes when you say it. Then he leans back slightly, satisfied, like he’s corrected your posture into something he can tolerate.
It becomes the first true exchange between you — you give him language, he gives you a name, and in that small transaction the House shifts.
Not softer or safer, but a little less one-sided.
You don’t tell the facility staff when they come to check on you — two men in polo shirts and steel-toed boots, clipboard in hand, eyes scanning the interior like they expect to find you in pieces —you give them numbers and controlled vagueness.
“He’s responding to basic cues,” you say. “Recognition is improving. I’m building a vocabulary framework.”
They ask if he’s vocalizing.
You let your face do what you’ve trained it to do in rooms full of men who believe they own the conversation. You keep your expression bored.
“Occasional sound mimicry. Nothing consistent.”
They nod like they believe you.
They don’t ask more, because if they ask more, they have to admit the subject might be more than a dangerous animal, and that creates paperwork nobody wants.
When they leave, you lock the inner door and lean against it until your shoulders drop an inch.
Sukuna is at the far end, watching the whole time.
When your eyes meet through glass, he lifts his hand and taps the barrier once with a claw.
Not a request.
A reminder.
He learns fast in ways that make your skin go tight.
At first it’s repetition — he parrots short words you use often, not when you teach them, but when they matter.
“Food.” “No.” “Stop.” “Come.”
The words scrape out of him as if he’s pulling them from the back of his throat with claws, but they are recognizable.
Then it becomes pattern.
He starts anticipating which words belong to which actions.
If you say “later” in the tone you use when you’re exhausted, he shifts his posture like he understands it’s not a refusal, it’s a postponement.
If you say “careful” when you’re cleaning a filter and your hand is too close to the waterline, he goes still in a way that feels deliberate, like he’s proving he can restrain himself when it serves him.
And then, quietly, he starts using language like a blade.
You discover it on a morning when you’ve slept poorly and your patience is thin.
The coffee tastes burnt.
The air feels too cold.
Your shoulders ache from tension that never fully releases.
You’re writing at the desk, knee bouncing under you, and you mutter to yourself.
“I hate this place.”
His voice comes from the shore ledge behind the glass, low and unhurried.
“Leave.”
Your pen stops.
Slowly, you turn your head.
He’s half out of the water, chin tilted slightly, eyes fixed on you with that infuriating calm.
“You know I can’t.”
He blinks once.
“Try.”
The word isn’t encouragement, it’s provocation.
Like he wants to watch you run into the walls until you admit they’re real.
You swallow hard and go back to your notes.
“If you’re going to talk, at least learn not to be an asshole.”
A pause.
Then, almost conversational.
“Asshole.”
You glance up before you can stop yourself.
He shows a flash of teeth that might be a grin.
Might be a warning.
“Learn.”
It becomes your reluctant routine — teaching him words in between living.
Not formal sessions, not neat flashcards, life leaking vocabulary into the space until it sticks.
You label objects around the land side with masking tape and thick marker — TABLE, SINK, BED — mostly for him, partly for yourself, as if naming things keeps you sane.
One afternoon you find the tape peeled off the cabinet and stuck crookedly to the glass, right at eye level on the water side.
Sukuna is at the ledge, one hand resting against the barrier, claw tip tapping the word you wrote.
“Sink.” he says, and the vowel is almost perfect.
You stare at him.
“Why did you move it?”
His gaze flicks to the cabinet, then back to you.
“See.” he says.
As if the entire point of language is to make you look where he wants you to look.
You teach him games because boredom is its own kind of erosion.
The first time you bring out a jigsaw puzzle, you do it on a whim born from desperation.
The House is too quiet. Your thoughts are too loud. You need something that isn’t observation, isn’t survival.
You sit on the floor by the glass with the pieces spread out on a tray.
It’s a picture of an ocean scene, chosen without thinking, and you hate yourself for the irony the moment you open the box.
Sukuna drifts closer, curious in that predatory way where curiosity is never harmless.
“What.” he asks, voice rough.
“A puzzle,” you reply. “It’s—” you pause, searching for a definition that doesn’t sound childish. “It’s a problem that doesn’t hurt anyone.”
He makes a sound in his throat that could be laughter if he were the kind of creature who laughed freely.
You start sorting pieces by color and edge.
You don’t invite him. You don’t assume.
You simply work, hands busy, mind quieter.
After ten minutes, a shadow falls over the tray.
You look up.
He’s surfaced at the glass, one hand lifted.
His claws drag lightly against the barrier, a slow scraping sound that makes your nerves jump.
He points — an unmistakable gesture — at a cluster of edge pieces you’ve missed.
You frown.
“You want to help?”
His eyes narrow like you’ve suggested something absurd.
You slide the tray closer to the glass, leaving a few inches between it and the barrier.
He studies the pieces through the glass for a long moment. Then his hand lowers out of sight, and a minute later his claws appear again — this time at the waterline near the ledge, dipping just enough to nudge one piece with the tip.
He doesn’t push it randomly.
He nudges it into alignment with another, fitting the shapes like he can feel the logic of it through instinct.
You go still.
The ridiculousness of it almost makes you smile.
A great white-shark-merfolk, tattoos and scars and blood on his teeth, carefully matching cardboard edges like it’s worth his time.
“You’re bored.” you say.
He doesn’t deny it.
“Do.”
You snort softly and keep working.
You don’t say thank you — it feels too intimate.
Instead you talk about the picture, about how the artist got the light wrong, about how the sea isn’t that color except in shallow tropical water, and how this facility doesn’t smell like any ocean you’ve ever loved.
He listens while pretending not to.
By the end of the day the puzzle is half finished.
He’s contributed more than he’ll ever admit.
You leave it on the tray overnight.
In the morning, you find three more pieces aligned — set into place with claw marks scratched faintly into the cardboard.
He did it while you slept.
It should unsettle you.
It does, a little.
It also does something worse — it makes the House feel less empty.
The first time he lets you into the water is not a gift more than it’s a bargain.
It’s been months — enough time that seasons have changed outside the facility, enough time that your muscles have started holding tension like it’s natural, enough time that you’ve stopped counting days in your head because the count makes you feel trapped.
You miss the ocean the way a starving person misses food.
Not the idea of it, the pressure, the sound of your own breath through a regulator, the feeling of weightlessness that makes your mind quiet.
You are surrounded by it on the outside, sure, but you are also near a cliff.
If you dive, the waves and rocks will make sure that it’s the last time.
You talk about it without meaning to.
One night you’re scrubbing the counter and your hands stop, and you hear yourself say.
“I would give anything to dive again.”
Sukuna is half on the shore ledge, eyes open, watching you like he watches everything that matters to him.
“Anything.” he repeats, voice low.
You stiffen.
“No—”
He doesn’t move.
“Water.”
The word is simple, the meaning is not.
You turn slowly, rag clenched in your hand.
“You can’t be serious.”
His gaze doesn’t flicker.
“Want.”
It isn’t a question — it’s an accusation, like wanting is a weakness you’ve been careless enough to show him.
You set the rag down carefully, because sudden movements feel like invitations in this place.
“Yes. I want to. But I’m not getting in there unless I know I’m coming back out.”
A pause.
Then, almost lazy.
“My choice.”
Anger flares, hot in your chest.
“You don’t get to—”
He shifts, and the water ripples around his body with quiet power.
His hand lifts and taps the glass twice.
“Your choice,” he corrects, and there’s something almost amused in the way he says it. “Ask.”
It takes you a moment to understand.
He wants you to ask him, like he’s the gatekeeper.
Like the water is his territory and entry is something you request.
You should refuse on principle.
You don’t.
Your throat works around pride and fear and the raw, aching need to feel water around your body again.
“Will you let me swim?”
His eyes narrow, and you can’t tell if he’s pleased or if he’s simply satisfied to see you swallow dignity.
“Yes.” he says, and the word is so clear you feel it in your ribs.
Then he adds, softer, like a condition tucked into the seam of the promise.
“No run.”
You blink.
“Run where?”
He shows teeth, brief and sharp.
“Land.”
If you enter the water, you do it knowing you can’t use it as a sprint to freedom — can’t use distraction to slip out a door while he’s occupied.
You’re not just asking for permission to swim.
You’re agreeing to stay in the House.
You laugh once, short and humorless.
“Sukuna, there’s nowhere to go.”
He watches you like he doesn’t believe that.
Like he’s filing away every door, every lock, every routine.
“Ask.” he repeats, impatient now.
You exhale.
“If I go into the water, you won’t hurt me.”
A beat.
Then, deliberate.
“No hurt.”
“And if I panic—”
“Hold.”
Your stomach twists.
“You’re saying you’ll hold me?”
He nods, once, minimal.
It’s the closest thing to reassurance he’s ever offered, and it shouldn’t mean anything because it comes from the mouth of a predator.
It means everything anyway.
You don’t have a wetsuit.
The facility didn’t provide one because the protocols forbid entry.
You improvise — long-sleeved shirt, tight pants, hair braided back, a length of rope you knot around your waist like a crude safety line with the other end looped around a bolted ring on the shore.
It’s pathetic compared to real dive gear, but it gives your hands something to trust.
Sukuna watches the preparation with a kind of stillness that makes your skin crawl. Not impatient, just focused. Like he understands the ritual of readiness and respects it in his own twisted way.
When you step down into the water, the cold shocks you hard enough that your breath stutters.
He’s right there, close enough that the shadow of his body turns the water darker around you.
He doesn’t touch you immediately.
You wade in to your thighs, then waist.
The waterline climbs your ribs.
Your heart hits too fast, your body remembering the day he dragged you without consent.
You stop.
Sukuna’s voice comes, low, near your ear though he’s not close enough to be speaking into it.
“Breathe.”
The word is blunt. Not comforting. An instruction.
You force air in through your nose, out through your mouth.
Once. Twice.
Your shoulders lower a fraction.
You step deeper until you float.
The moment your feet leave the floor, something in you loosens. Not fear.
Something older than fear.
Your muscles stop fighting gravity they don’t need to fight.
Your arms drift outward.
Sukuna moves then, silent, sliding under you like a current.
His hands come to your waist — not tight, not possessive, just present, anchoring you the way he promised.
Warm through fabric.
You swallow water-nervousness and let yourself be held, because the alternative is thrashing and giving him a reason to clamp down harder.
You look down into the blue and feel the old ache flare — This is still a tank.
Glass. Edges. Controlled currents.
An ocean made to be watched.
But it’s also water, and for the first time in months you feel like your body belongs to itself again.
You paddle cautiously, testing the space. Sukuna stays close enough that you can feel his wake, like a presence at your back.
When you drift too near the deeper end, he bumps your hip gently with his shoulder and steers you back toward the shallows with the ease of something that has navigated currents its whole life.
He doesn’t speak much in the water. His body language is its own sentence.
After you’ve swum a few slow laps, after your breathing steadies and the shaking in your limbs fades, you risk something else.
You turn toward him.
He hovers in the water, torso upright, shark body angled behind like an engine poised to move.
His eyes are on you, unblinking, patient.
“I want to see,” you say, voice trembling slightly with cold. “Your—” you gesture, embarrassed by how clinical you sound and how personal it still feels. “Your fins. The scars. The dents. Let me... look properly.”
He watches you for a long moment.
Then he drifts closer and turns, presenting his side like he understands exactly what you’re asking for.
Your hands hesitate.
Touching him in the water feels different than touching through glass.
There’s no barrier now.
No illusion of safety.
You reach out anyway.
Your fingers meet the texture of his shark skin, and you have to swallow hard.
It’s rough — fine ridges like sandpaper, designed to reduce drag. Your fingertips catch on old scars, on healed torn edges.
You trace the dent in his dorsal fin carefully, not pressing, not trying to hurt.
Sukuna doesn’t flinch.
He doesn’t pull away.
He lets you study him.
It becomes part of your weeks after that — you in the water once a day, sometimes more, not for the facility’s data but for your own sanity, and Sukuna allowing it with the same grudging tolerance he shows when you talk too much.
You learn the geography of his body the way you learned reefs and kelp forests — by slow, patient observation.
You find a deep scar low on his flank that looks like a harpoon strike. You hover there, fingers brushing the thickened tissue, and your throat tightens.
“Humans did that.” you say quietly.
His gaze flicks to you.
Something sharp moves behind his eyes.
“Many.” he answers.
You nod, because you have no defense for your species.
You also learn his boundaries.
He doesn’t like you touching the gill slits along the sides of his shark torso, the first time you try, curious, his hand snaps out and catches your wrist — not painful, but immediate, claws pressing just enough to stop you.
“Not.” he says, voice low.
You swallow.
“Sensitive?”
A pause. Then.
“Mine.”
Possessive again.
Not a refusal of your curiosity, a claim that some parts of him are not for you.
You respect it.
Because you don’t have many choices, and because in this place, respecting the boundaries he sets is one of the only ways you keep yourself alive without feeling like you’re groveling.
You become careful about what you report to the scientists.
You give them improvements in incremental drips.
“Responds to basic vocabulary,” “Recognizes self-referential markers,” “Problem-solving capacity consistent with high intelligence.”
You sprinkle in enough technical language and cautious skepticism to keep them from getting excited.
You do not tell them he has a name.
You do not tell them he can string words together when it suits him.
You do not tell them he’s watching the door routines, the supply schedules, the way the outside staff shift their weight near certain locks.
They want results.
You give them just enough to keep their interest and stave off the kind of impatience that turns into scalpels.
A year passes in a way you only notice when you find yourself marking the date on a form and realizing your hand is writing numbers that should belong to someone else’s life.
You and Sukuna settle into a strange, tense coexistence.
He is not sociable.
He does not seek comfort the way a dog would, the way a dolphin might.
He tolerates proximity because he chooses to, and he makes sure you never forget it.
But he does not mind laying half on the shore and listening to you talk.
There are days you come to the waterline with your notebook and sit with your legs dangling in the shallows, ankles wet, and he surfaces nearby like a shadow deciding it can be seen.
He rests with his forearms on sand, chest out, eyes half-lidded.
You talk about nothing on purpose.
About the way the facility coffee tastes like burnt paper. About a book you remember from childhood. About the ocean you’ve never gotten to dive — the trenches you’ll probably never see, the deep scattering layer you’ve only studied in data points.
He listens in silence, and sometimes he interrupts with a single word that proves he’s been tracking your meaning, not just your sound.
“Trench.” he repeats once, voice thick. “Deep.”
You look at him.
“Yes.”
He watches you, then says, slower, as if shaping it costs him,
“Want.”
You blink.
“You want to go deep.”
A flash of tooth.
“Always.”
It’s one of the few times you hear something like sincerity in him, and it hits you harder than it should.
He amuses himself with your body like you’re a puzzle he hasn’t solved.
It starts with ankles.
You’ll be sitting at the waterline writing notes, half relaxed because you’ve done this a hundred times, and then a hand closes around your foot and your entire nervous system lights up.
Sometimes you yelp and kick reflexively, and he holds firm, dragging your leg just far enough that you lose balance and fall back onto the sand with a curse.
He doesn’t drag you under.
Not then.
He lifts your foot — your human foot — up to his face with a kind of fascinated disdain, as if he can’t decide whether it’s ridiculous or intriguing.
His claws trace the curve of your arch, light enough not to break skin, sharp enough that you feel every point.
He presses a fingertip to your toes and spreads them slightly, testing the range of motion like he’s cataloging anatomy.
He sniffs, slow and deliberate.
You squirm because it’s invasive in a way you can’t quite define, and because you’re ticklish and he learns that fact with immediate, vicious delight.
“Stop.” you gasp, laughing despite yourself, voice wobbling with discomfort and involuntary humor. “I’m ticklish— stop!”
He doesn’t.
His mouth curves, and you see teeth.
“Tick,” he says, mangling the word as if it offends him. “Lish.”
“Oh my god,”you spit, still laughing, trying to twist away. “You’re— you’re such an asshole.”
He makes that low sound again, the almost-laugh.
His claws pinch lightly at the ball of your foot.
You shriek and slap your back into the sand, hands scrabbling for something to grab, and your laughter turns breathless.
He watches you with bright, predatory interest like he’s found a weak point that isn’t about survival.
You bend enough to press your palms to his face, shoving at his cheekbone, trying to make him let go.
His skin is warm under your hands. Wet. Rough at the edges.
“Let go,” you say, and your voice breaks on another involuntary giggle.
His eyes narrow.
A sound rolls up from his chest, deeper, guttural. Not quite a growl, not quite a warning.
Something possessive and irritated, as if your hands on his face have crossed an invisible line.
Then he yanks.
Not hard enough to hurt.
Hard enough to punish your overconfidence.
Your body slides toward the waterline in a rush, sand giving way, and then you’re in the shallows with a gasp, cold water swallowing your laughter.
He drags you in with casual strength, not for harm, not for anger — because he can, because it reminds you where the boundary sits, because being an asshole is one of the only games he’s ever mastered.
You sputter, glaring at him, hair plastered to your face.
“You’re enjoying this, bastard.”
He blinks, then says, calmly,
“Yes.”
The honesty is outrageous enough that you can’t help it — you laugh again, half furious, half stunned.
He watches the sound come out of you like it’s another language he’s learning.
There are other moments, quieter, that make the year feel less like punishment.
You find out the glass ceiling can open by accident — an automated maintenance cycle triggered by a power fluctuation one evening.
There’s a soft mechanical whine, then a seam above you shifts, and cold night air pours in, carrying the scent of real salt from the outside coast.
You freeze in the center of the land side, head tilted up.
The opening is narrow, reinforced with mesh and bars, not an escape route — another tease — but it reveals the sky.
Stars, sharp and bright in the absence of city light.
A thin moon.
Clouds moving fast, chased by wind.
Sukuna surfaces at the shore ledge and looks up too, his face angled toward the opening.
His expression doesn’t soften — he doesn’t do softness, but something in the stillness of him changes, as if the sky is a reminder of depth and distance and everything he used to have.
You lower yourself onto the sand near the waterline, damp hair still dripping, and you stare up at the stars until your eyes ache.
He shifts closer and settles half in, half out, his shoulder near your thigh, close enough that you feel warmth radiating from him.
He doesn’t touch you yet, he simply occupies the space the way he always does — like a claim, like an allowance.
You talk because silence makes the fear louder.
You talk about constellations you remember.
You talk about how sailors used to navigate by them.
You talk about how cruel it is that you can see the sky and still be trapped under it.
He listens with his eyes on the stars.
When your voice starts to thin, when your words stumble because exhaustion is creeping up your spine, he shifts his head slightly, gaze cutting toward you.
“Sleep bad.” he says.
You blink.
“What.”
He repeats it, slower.
“Sleep... bad.”
It isn’t a question, but it forces one out of you anyway.
“How do you know?”
He lifts one hand and taps two fingers against his own chest, right over where a human heart would be, then gestures toward you.
“Hear,” he says, and the word lands wrong, too intimate. “Smell.”
Your stomach twists.
Of course he can.
Of course he’s been tracking you by things you can’t hide.
You try to scoff it off.
“I’m fine.”
His gaze holds you. It doesn’t buy the lie.
“Talk.” he says again, but the tone is different tonight — less command, more insistence, like he knows you’ll fold if he leans the right way.
Your jaw tightens.
“You don’t get to—”
He shifts, and his clawed hand comes to rest on your calf.
Not gripping, just there.
The touch is warm against your skin, and the claws drag lightly, careful, drawing absent shapes the way someone might doodle on paper without thinking.
The gesture hits you somewhere tender and unguarded.
It shouldn’t.
It’s Sukuna.
He’s cruel.
He’s a predator.
He dragged you into the water for sport and watched you panic like it entertained him.
And yet his claw keeps moving in slow lines, not cutting, not threatening.
A steady sensation that anchors you to your body when your thoughts want to spin into panic.
You swallow hard and stare up at the stars.
The words come out before you can decide to stop them.
“I’m afraid of what happens when this ends.” Your voice is thin, low, tired and ther’s fear there.
Sukuna’s claw pauses.
The pumps hum. The tide breathes.
He doesn’t speak right away, and the silence gives your fear room to expand.
You force yourself to keep going, because if you stop now you’ll never say it, and the unsaid will rot in your chest.
“If they find out you can speak— really speak, not just... repeat— if they learn you understand... they’ll take more of your kind.”
His hand resumes, slower now, the claw tip tracing the curve of your calf like he’s thinking through your words.
“They’ll hunt,” you continue, voice quiet and raw. “They’ll capture. They’ll build more tanks. They’ll call it research. And I won’t be here to—” you choke slightly on the truth. “I won’t be here to slow them down.”
His gaze shifts to you, sharp.
“It is not,” he says, careful, “your problem.”
You laugh once, breathy, bitter.
“You keep saying that like it’s a fact.”
“It is,” he answers. Then, harsher, as if anger is easier than honesty “Lose sleep. For what. Humans do human things.”
You turn your head just enough to look at him.
“That’s not comforting.”
His mouth curves.
The expression is cruel by default, but there’s a tension under it, a strain like he’s balancing something he refuses to name.
“You think you save.”
You flinch, because it hits close.
You have been feeding him, hiding him, managing their expectations, lying by omission every time the staff comes to check your progress.
You tell yourself it’s strategy.
You tell yourself it’s ethics.
You tell yourself it’s the least you can do.
He watches the flinch like he wanted it.
“You small,” he says, and the insult would be easier to swallow if his hand weren’t still on your calf, claws moving in a slow, absent pattern. “They big. You think you change big.”
You grit your teeth.
“Maybe I can’t. But that doesn’t mean I don’t care.”
His eyes narrow, and for a moment you see something behind the red — something like processing, like he’s turning the idea over and testing it for teeth.
“Care.” he repeats, as if it’s a foreign concept he resents understanding.
You stare back up at the stars.
Your voice comes out softer, tired in a way that strips the fight from it.
“You became important to me. That’s... that’s what happens when you trap two living beings in the same cage and tell one of them it’s science.”
He makes a low sound, unimpressed.
“Important.”
“Yes.”
He shifts slightly, enough that his shoulder brushes your thigh.
His hand stays on your calf.
The claws draw a new shape, aimless, almost gentle.
“You talk too much.” he says finally, and the insult is familiar enough that it almost feels like comfort.
You exhale a shaky laugh.
“You keep telling me that, and you keep listening.”
He doesn’t deny it.
Denial would be vulnerability.
Instead, he changes the subject with the precision of someone who wants control back.
His gaze flicks over you, down, then up again, and he says, flat as a blade.
“Ask.”
You blink.
“Ask what.”
His mouth curves, and you know immediately he’s going to make you regret engaging.
“You think. Many times. Body.”
Heat crawls up your neck.
“What.”
He watches you flounder, pleased in that predatory, patient way.
“My body. You look. You touch. You write. You do not ask... here.”
His claw taps lightly against his own lower torso where human anatomy would transition into shark.
Your face goes hot, and your brain goes blank in the way it does when something humiliating is dragged into light.
“You’re—” you swallow hard. “You’re talking about reproductive anatomy.”
He bares teeth in a smile that isn’t friendly.
“Yes.”
You stare at him, mortified.
“Why do you care.”
He shrugs — an awkward motion with shoulders built for land and water both.
“You want know. You shake when you think.”
“I don’t shake.” You say too fast.
His eyes flick to your hands.
Still.
Then to your throat.
A pulse you can’t control.
“You do,” he says, calm and awful. “Ask.”
You sit up a little, heart banging, because you want distance from the topic and there isn’t any in this House.
“Fine. If we’re doing this as science, then—” you hate the way your voice speeds up, the way it becomes too clinical because you’re nervous. “Great white sharks have internal fertilization. Males have claspers, paired structures. In a merfolk hybrid, I would assume there’s some analogous—”
His expression turns smug, as if he’s pushed the right button and is watching the machine run.
He lets you talk, lets you spiral into hypothesis because he knows it’s how you cope.
When you finally choke to a stop, cheeks burning, he leans closer by an inch.
“Two.” he says.
You blink.
“Two... claspers.”
He makes a sound of dismissal, then corrects you with infuriating simplicity.
“Two. Different.”
Your stomach flips.
“Different how?”
His eyes glitter with amusement.
“You write. You do not look at my face. Coward.”
“Shut up,” you hiss, but you do pick up your notebook because it gives you something to do with your hands.
He speaks slowly, choosing words like he’s selecting weapons.
He doesn’t offer you a pornographic lecture, doesn’t turn it into something explicit — he keeps it frustratingly vague while still making sure you understand the point — his body isn’t neatly boxed into your textbooks.
“Not outside,” he says. “Not easy. Hidden. For water. For... eggs.”
He tilts his head, watching you scribble, then adds, like a knife twist,
“You want see. Someday.”
Your pen stutters. You don’t look up.
“That’s not necessary.”
He hums, unimpressed.
“Liar.”
You grip the notebook tighter.
“I’m trying to be professional.”
“You are in my tank,” he says, and the words land with quiet dominance. “There is no professional.”
You can’t argue with that without admitting how much of your life has already become something else.
He shifts away then, as if bored now that he’s gotten what he wanted — your fluster, your honesty, your nervous words spilling into the air like chum.
He drifts back toward deeper water, body rolling into shadow with an ease that makes your human limbs feel clumsy by comparison.
Before he disappears fully, his voice carries back, low and casual, like an afterthought.
“Sleep.”
Then he’s gone, leaving you with the stars and the cold air and the realization that you’ve started relying on him the way people rely on the only other living thing in solitary confinement.
You lie back down on the sand, notebook still on your chest, and your eyes stay on the sky until exhaustion drags them shut.
Somewhere beside you, you feel the water shift — a subtle change in current, a presence moving closer to the shore ledge again.
You don’t open your eyes.
You don’t have the energy to police your own vulnerability.
Sukuna settles half on the shore, close enough that his warmth reaches your leg.
His breathing is slow. The tide keeps moving. The ceiling remains open, letting the night exist above you as proof that the world keeps going even when you don’t.
His claw returns to your calf for a moment, tracing one last absent line — an idle shape, a quiet insistence that you stay tethered to your body.
And you fall asleep like that, talking yourself into silence under the stars, with a predator at your side who never stopped being ominous, who never stopped enjoying the fact that you know it, and who still — by choice — stays close enough that you don’t feel entirely alone in the prison disguised as science.
ETHOGRAM ENTRY IV — Year 3: Terminal Sampling and Summer Storms
The envelope isn’t an envelope — just a thick manila packet sealed with a strip of red tape and stamped twice with the institute’s emblem like someone wanted to make sure you understood it belonged to them before you even touched it.
It arrives with the supply drop, slid across the outer threshold by a man who won’t meet your eyes. He’s a rotating contractor, new enough that he still carries the discomfort openly, hands moving fast as if the house might bite him for lingering. He makes a joke about the weather, about the storms rolling in so early this summer, and you nod in the right places because you’ve learned how to be normal while your stomach coils.
When the door seals again, the air changes.
Not because the air itself is different — same damp warmth, same faint chemical cleanliness of filters — but because you’re alone with the sound of your own heartbeat, and you can feel Sukuna watching from the water without needing to look.
The packet is heavy in your hands. Heavier than paper should be.
You don’t open it right away.
You set it on the counter next to the fruit that always arrives too green and the sealed protein packs labeled with barcodes you stopped reading months ago. You rinse your hands as if you’ve touched something dirty. You dry them. You rinse them again anyway. It’s pointless, but it gives you a rhythm to hold.
Then you pick the packet up and carry it to your desk like you’re transporting a live thing.
From the desk you see the glass tank and the shore with ease. It was designed that way, not for your convenience but for observation — to keep your work in his view, to keep you both reminded you are always seen even when there is no camera.
Sukuna surfaces near the shore ledge. He doesn’t make a show of it. He simply rises until his forearms rest on the sand and his shoulders breach, water streaming down inked skin. His gaze fixes on the packet as if he can smell the change in your mood through paper.
“You shake.” he comments.
“I’m fine,” you answer automatically, and hear the lie the moment it leaves your mouth.
His mouth curls, sharp. He also hears it.
“Liar.”
You sit down. The chair feels too hard, too ordinary for what you’re about to read. You cut the tape with a letter opener and slide the contents out — the pages are clipped, typed, clean.
There’s a cover sheet with a project code, your name, and — under it — NEXT PHASE DIRECTIVE.
The words make your lungs feel smaller.
You skim the first paragraph and get hit by the tone that always makes you cold — the way men write when they’re excited but pretending they aren’t.
Cautious language hiding appetite.
You read about “extended cognitive acquisition,” about “neuroplastic adaptation,” about “functional mapping.” You read about “post-learning anatomical correlates.”
Your eyes snag on a line that’s meant to look innocent.
You turn the page, faster now, needing to see the shape of it even while your body tries to reject it.
There are diagrams, bullet points, a section titled SURGICAL ACCESS CONSIDERATIONS and another titled CRANIAL ENTRY & TISSUE PRESERVATION.
You stop breathing properly without realizing it.
They dress it up in careful words — minimizing distress, ensuring data integrity, maximizing yield — but it all translates into the same brutal sentence — We are going to cut him open and look at his brain.
Not to heal. Not to help. To own the proof of what you already know.
You see your own contributions referenced like citations — As per Operator’s reports of fluent comprehension… As per demonstrated literacy markers… As per sustained behavioral stability…
The irony is sharp enough to make you dizzy.
You did your job too well.
You kept him alive long enough for them to decide he’s worth dissecting.
At the bottom of the directive is a timeline:
Phase scheduled to commence within 10 – 14 weeks.
A few months.
Plenty of time, the paper implies, for you to adjust.
To accept.
To prepare him for the knife as if you’re training a dog for a vet visit.
Your throat tightens. Your eyes blur. You blink hard and force the words to stay in focus.
A final paragraph, almost casual, informs you they will be sending a surgical team to the island for pre-op evaluation and sedation tolerance trials.
It mentions “operator oversight recommended,” as if that’s a kindness.
As if you could sit and watch them gutting Sukuna in front of you and call it a wednesday.
You sit back in your chair and realize your hands are clenched into fists so tight your nails have bitten crescents into your palms.
Across the false beach, Sukuna watches you without moving. His eyes are wide, pupils dark, red rim thin like a warning line.
“What.” It’s not a question you can dodge.
You open your mouth and nothing comes out.
Your tongue feels too thick. Your chest feels full of water.
Sukuna’s head tilts. The faint impatience in him sharpens.
“Read,” he says, one claw dragging on the damp sand of the shore.
You look down at the packet again.
The words swim.
You force yourself to stand.
Your legs feel wrong, as if your body is trying to detach from the decision your brain is about to make.
You carry the pages to the shore and hold them up.
Sukuna’s gaze drops to the paper.
He can read enough now that he doesn’t need you to translate everything, and the realization makes your stomach sink further. You were afraid to teach him because you feared it would be used against him. You taught him anyway, in fragments, in nights where it felt like the only honest thing you could give.
Now he reads his own death sentence.
His eyes move left to right, slower than yours, but steady. His jaw tightens as he hits certain words.
He looks up at you.
“Cut.” he says, and the word comes out flat, too controlled.
You swallow the lump in your throat and ignre the burn behind your eyes.
“Yes.”
He doesn’t ask why. He doesn’t ask what they gain.
He already knows how humans work.
What he doesn’t understand is why your face looks like you’re the one about to be strapped down.
“They want your brain,” you say, voice rough. “They think— they’re convinced—l earning changed it. They want to see what it looks like.”
Sukuna’s mouth curls, not amusement this time, something colder.
“They want proof.”
“Yes.”
He stares at you for a long moment, then says,
“They will try.”
The certainty in his tone should comfort you. It doesn’t. It only sharpens the dread, because you know what happens when an institute’s arrogance meets a predator’s refusal.
You press your palm to the glass wall besides you. It’s cool, firm, indifferent.
“They’re coming here,” you whisper. “In a few months.”
Sukuna’s gaze doesn’t leave your face.
“And you.”
The question sits there unspoken — What will you do.
Your throat works. You could lie, pretend you’ll follow procedure, that you’ll play your role, that you’ll be the good scientist until the last moment.
It would be safer to lie.
Safer for you, at least.
But you’ve already decided.
The decision has been forming in you for months, a slow, stubborn growth fed by every time they called him a specimen, every time they dismissed your warnings as emotion, every time they refused to answer what would happen “after.”
You exhale shakily.
“I won’t let them.”
Sukuna’s eyes narrow. He studies you like he’s weighing whether you understand the scale of what you’re saying.
“You will lose,” he says, voice low. “Job. License. Freedom. Everything.”
“Yes.”
He blinks, slow, as if the concept tastes wrong.
“Stupid.”
You almost laugh at that, a jagged sound that doesn’t make it fully out of your throat.
“You keep calling me that.”
“Because it is stupid. You are.” he answers, flat.
You press your forehead to the glass for a second, eyes closed, as if that will make the world stop turning so you have an extra moment to think.
Your breath fogs the surface in a small cloud that fades quickly. Your feet are still in the water, on the damp sand — the lazy movements of the mimic waves lick your shins as you breathe deeply once again.
When you open your eyes, he’s closer, webbed hand wrapping around your ankle, not too tight. His gaze is sharp as he looks up at you, but there’s something else under it now — something like vigilance.
“Why.” he questions.
You swallow again, because the truth is too big to fit into a clean explanation.
“Because you’re not theirs.”
“That is not an answer.”
“It is, Sukuna.” you insist, voice cracking. “It’s the only one that matters.”
Sukuna’s jaw flexes. He looks away for a moment, toward the far end of the tank, toward the darker water.
When he looks back, his expression is controlled, but his pupils remain wide.
“You trade your cage for mine,” he says slowly. “You do this.”
“Yes.”
He holds your gaze, and you can feel the calculation in him. He is not sentimental, he does not romanticize sacrifice. In his world, you don’t give away your survival for someone else’s comfort.
You take. You keep. You endure.
The fact that you’re willing to burn your life down for him reads, to him, as irrational.
It also reads as… something else. Something he can’t name without execrating himself for it.
“You are reckless.” he finally mentions.
You give a small, exhausted nod.
“Maybe.”
He leans his forehead against the side of your thigh — you can see the fine texture of his skin, you watch for a moment the way water beads at the edge of his tattoos.
He’s really splendid, isn’t he?
“You will regret,” he says, and it almost sounds like a warning. “Humans always regret when they lose their nice things.”
You stare at him.
“I don’t own nice things.”
He raises his head again to look at you. His eyes narrow as if he wants to argue, then he stops. He knows you too well now. He knows you’ve been living on borrowed time, on a salary that came with isolation clauses and secrecy forms, on a life that can be erased the moment the board decides you’re inconvenient.
Your “nice things” are a lie.
He exhales, slow.
“Then you will survive without them.”
It’s not comfort. It’s an order.
You swallow the will to yell at him.
“I’m trying to figure out how.”
Sukuna’s gaze flicks to the packet in your hand.
“Not with paper.”
“No,” you whisper. “Not with paper.”
You don’t sleep properly that night.
You lie on the shore ledge with your feet in the water, head against a folded towel, staring at the ceiling panels where the stars should be.
You keep seeing words when you blink — cranial entry. tissue preservation. terminal sampling.
Sukuna stays half out of the water beside you, quiet, closer than he usually allows himself to be when you’re tense. His presence is a weight that keeps you from spinning into panic entirely.
At some point your voice breaks the silence.
“There’s a discharge system…” you say softly, more to yourself than to him. “The tank water can’t just… stay here forever. It would stagnate. Even with filters.”
Sukuna’s claw drags a slow line in the sand near your calf, absent, like he’s listening without making it easy for you.
“It flushes periodically,” you continue. “It’s controlled. Scheduled. They replace water. Adjust salinity. Temperature. It’s part of maintenance.”
He makes a low sound.
“And.”
“And in a storm,” you say, your mind racing, “the system prioritizes structural safety. Pressure relief. If the facility detects— if it detects certain parameters—”
Sukuna’s eyes slide to you.
“You can open.”
The words make your chest tighten.
“Maybe.”
He watches your face.
“You plan.”
“Yes.”
His mouth curves, faint and sharp.
“Smart.”
The weeks after that become a strange performance.
You keep sending official logs. You keep answering calls. You keep your tone even when they drop new details about surgical teams and “pre-op evaluations.”
You smile when you have to.
You make yourself look compliant.
And at the same time, you start doing small things that would look, on paper, like diligence.
You request maintenance data on the flush cycles.
You cite “water quality concerns.”
You ask for backup schedules, generator tests, emergency protocols.
You frame it as caution.
You frame it as care for the asset.
They give you what you ask for because they like a scientist who sounds anxious about the equipment rather than anxious about ethics.
They think you’re worried about their investment.
You are.
Just not in the way they think.
You start watching weather patterns obsessively.
Summer storms roll through the island chain with predictable violence — thunderheads building over warm water, wind shifting fast, lightning splitting the horizon. Sometimes the power flickers even with generator backup, brief stutters that make your lights blink and your pumps shift cadence.
You write those moments down. You time them. You learn what the system does when it’s stressed.
Sukuna watches you work with a stillness that feels like coiled patience.
He starts staying closer at night.
At first you tell yourself it’s practical — that he’s alert because he knows something is coming, that he’s monitoring you the way you monitor him. But then you fall asleep with your hand resting against his forearm and wake up to find him in the same place, his head angled toward you as if he’s guarding.
Once, you wake in the dark to the sensation of weight at your back.
You freeze, the animal part of you flaring awake.
Then you realize it’s him — his shoulder pressed lightly against your spine, his chest half out of the water, the shark half of him still submerged.
He’s closer than he ever is when you sleep.
You never knew you’d be so glad to wake up with wrinkled skin and smelling like seasalt.
You don’t move when he’s this close. You don’t speak also. You let your breath settle, you let your heart calm down.
In the morning, when you finally turn and look at him, his eyes are open.
“Why are you this close,” you ask, voice hoarse with sleep.
He blinks slow.
“You were shaking.”
“I wasn’t.”
“You were,” he says. Then, after a beat, as if grudgingly adding the real truth. “I do not like when you break.”
Your throat tightens.
“That’s… almost kind.”
He huffs, disdainful.
“Do not flatter yourself. You are useful.”
You roll your eyes and the sound of your laugh is small, but it loosens something in your chest.
He watches you with that quiet hunger that isn’t only appetite. It’s attention. It’s ownership.
It’s the bond neither of you will name because naming it makes it vulnerable.
The storm you choose isn’t chosen in a clean way.
It chooses you.
It comes in hard and fast on a humid afternoon when the sky turns the color of dirty cotton and the wind shifts so suddenly the gulls vanish as if someone snapped them out of the air. The ocean around the island turns rough, white foam breaking against black cliffs with relentless force.
The facility’s outer structure groans under it — metal complaining, concrete holding.
The lights flicker once. Twice.
The pumps stutter and then resume, but their cadence is wrong, strained.
Your heart climbs into your throat.
You glance toward the control panel.
Toward the utility hatch.
Toward the glass line upstairs where Sukuna is already surfaced, watching you like he knew this moment was coming before you did.
Your radio crackles with a voice from the outer hall.
“Power instability. Nonessential systems down. Stand by.”
You answer, voice calm because you’ve practiced calm.
“Acknowledged.”
Then you walk to the panel.
Your fingers hover for half a second over the controls.
You think of the packet, diagrams, men leaning over your work like hungry birds.
You think of Sukuna’s eyes reading the word cut.
You flip the sequence.
The facility reacts like a living thing startled awake.
Alarms begin low, then deepen.
Lights flash in measured intervals.
The tide stutters, then shifts — current changing, pressure balancing, water pulling toward the far end with a force you can feel even standing on land.
Sukuna’s pupils flare.
He moves instantly, body sliding through the water with silent power, heading toward the deep end where the pull gathers.
He doesn’t look confused, he looks… ready.
You should feel fear, and you do — it’s there, sharp at the base of your spine.
But over it is something steadier, resolve so stubborn it feels like gravity.
You keep your posture controlled, even as your hands sweat.
The lights flicker again. This time they go out for a full second before emergency power snaps in.
The hum changes pitch, somewhere in the structure, a door slams.
Sukuna surfaces at the far end, then turns his head and looks straight at you.
The current is strong now, water beginning to funnel toward the discharge route beneath the facility.
It’s working.
Your lungs tighten.
You realize you’re holding your breath already.
You force yourself to inhale.
The opening sequence begins.
You feel it more than you hear it, even though the sound is loud — pressure shifting through the tank, a deep pull like a throat opening somewhere under you. The water level doesn’t drop much, it simply starts moving toward somewhere else with intention.
In these sorts of events, if you were someone else, if their orders ruled over you, Sukuna would be kept in the tank section with the locking system working, separating him from the shore, deep and discharge area.
Sukuna’s voice carries across the water, low and clear.
“Come.”
Your stomach drops and you furrow your brows, alarmed at his invitation.
“No—”
“Come,” he repeats, sharper. Not pleading. Ordering.
You step back automatically, the human instinct to stay on land screaming.
He is already moving toward you, cutting through the shallows with force that makes the water slap the sand ramp.
His hands breach and almost grab your ankle, weren’t you a little farther back this time. He almost looks like he’s crawling on the dry sand if it means hauling you in.
It’s a sight as terrifying as it is magnificent.
His eyes are locked on you.
“You will not stay.” he snarls.
“I can’t— Sukuna, I can’t breathe underwater!” Your voice catches. “I’ll drown.”
He bares teeth, impatient.
“You will not.”
Your heart is pounding so hard it hurts. The storm hammers the island. The lights flicker again, and you realize with a sudden clarity that if you hesitate too long, the moment will pass. The system will stabilize. Someone in the outer hall will override.
You will lose the only opening you’ve created for him.
He will lose his only opportunity to escape for you.
Sukuna reaches for you.
His hand closes around your ankle, not tugging playfully the way he used to when you wrote with your feet in the water. This grip is steady, purposeful, he pulls you closer until your feet slide in wet sand and the water climbs your calves.
“You said you would pay,” he says, eyes burning. “Pay now.”
Your throat tightens with panic, you shiver, tremble, you need him to go.
“This wasn’t— I didn’t—”
“You plan for me,” he cuts in. “You do not plan for you. Stupid.”
The word lands, but it doesn’t sting the way it used to. It sounds like fear disguised as insult.
You swallow hard, eyes on his face.
“I can hold my breath.” you say out loud as it would make it true.
“Yes,” he agrees.
“I can manage pressure.” you spurt and still you are shaking.
“Yes.”
“But—”
Sukuna’s hand shifts from your ankle to your waist, and he hauls you forward with terrifying ease, pulling you into him until your body is flush against his chest.
Your breath catches at the warmth of him and the cold of the water that’s still rivuleting down his body.
Your mind tries to bolt.
Your muscles tense.
He locks one arm around your back, the other under your thighs, tucking you in tight so your limbs won’t flail in the current.
You feel your body physically shaking, vibrating almost, a buzz mixing fear and adrenaline.
“Hold.” he orders.
You wrap your arms around his neck like it’s instinct, fingers digging into tattooed skin.
The water climbs your ribs as he backs into the deeper section. The current pulls harder now. You can feel it in the way your body wants to drift, wants to be taken.
Sukuna turns his head slightly, mouth close to your ear.
“Do not fight,” he says. “Do not waste air.”
You nod, sharp, because if you try to speak you’ll panic.
You pull air, mouth closed tight, eyes shut. Ready.
Then he sinks.
The water closes over your shoulders, your head, the last warmth of air disappearing as you go under.
Sound becomes muffled thunder.
The storm is a distant roar.
Your world narrows to the pressure in your ears and the hard hold of his arms around you.
You keep your eyes shut, because seeing the tunnel mouth approach — seeing the dark opening where the water disappears — might break your concentration. You focus instead on sensation, his chest firm against yours, his grip unyielding, the steady power of his tail driving you downward through a current that wants to swallow you.
Your lungs start counting immediately.
Not panic yet, just awareness.
You’ve trained for breath holds. You’ve dived. You know how to relax your diaphragm, how to let the urge pass without obeying it.
You try your best.
The discharge tunnel takes you like a fist.
The current becomes violent, confined. You feel your body jolt as the flow accelerates. Sukuna tightens his hold, shielding your head against his shoulder, turning his body so if anything hits, it hits him first.
Your ears pop painfully.
Your sinuses burn.
Your lungs begin to ache.
You keep your arms locked around his neck, trying your best not to sink your nails into his skin but at some point you can’t help yourself. You keep your mouth sealed and count in your head, but the numbers smear as the tunnel shakes and the water roars.
You lose the sense of time.
Everything becomes pressure and movement and the desperate discipline of not letting your body thrash.
Your lungs scream.
Panic tries to ignite.
A bright, stupid flare — air, air, air.
Your fingers tighten until your knuckles hurt.
You let the air go in a blurt of bubbles as you welcome the pain, the water, the agonizing slow death that is to drown—
Except you don’t.
Sukuna shifts his grip as he notices your lungs losing the long battle, bringing one hand up to your jaw.
His claws press lightly, controlling your face.
Then his mouth covers yours.
Warm pressure. A seal.
He exhales, controlled, forcing air into you.
It isn’t gentle, it’s survival delivered with his own dominance. He gives you breath like he gives you everything else — as if you belong to him and staying alive is part of his property.
Air fills your mouth, your lungs. Relief hits so hard it almost makes you cry, but you swallow it down because you can’t waste anything.
He pulls back just enough to keep moving, his eyes open in the dark, pupils blown wide.
“Hold.” he mouths, the word more felt than heard.
You nod, and he continues down the tunnel with brutal steadiness.
Your lungs start counting again.
The ache returns.
The tunnel seems endless.
It goes down,
down,
down,
down…
Your mind starts to slip, edges fuzzing as oxygen debt builds.
Sukuna presses his mouth to yours again, another controlled exhale, another forced gift of air that keeps the darkness from swallowing you completely.
You cling to him like a lifeline because he is one.
Time becomes strange.
You don’t know if it’s minutes or hours.
Your body says it’s too long either way.
Then the water changes.
You feel it — cold sliding in, the current shifting from engineered pull to chaotic ocean movement.
Space opens.
The roar diffuses.
Sukuna drives forward with a final hard sweep of tail and you burst out of the tunnel into open sea.
Even underwater, the ocean feels different.
Less contained. More alive. Colder. Heavier.
He swims hard, putting distance between you and the outflow mouth.
You keep your eyes shut anyway, because the black-blue void makes your stomach flip.
Your lungs ache again. The cold tightens your chest.
You are trembling in his arms, and the tremble wastes oxygen.
Sukuna angles upward, smart and controlled, not straight for the surface where waves would slam you. He keeps you close to his body, using his bulk as a shield.
Your head swims.
Darkness presses at the edges of your vision even with your eyes closed.
His mouth finds yours again — warm air floods you, you inhale reflexively, then force the breath to settle.
You feel his teeth graze your lip — not a bite, just the presence of them, a reminder of what he is even as he keeps you alive.
Then your face breaks the surface.
Air hits your throat like fire.
You gasp so hard it hurts, lungs pulling in salt-scented wind and spray.
You cough, sputter, then suck in more air anyway because you need it.
The storm is chaos above water. Wind screaming. Rain sharp against your skin. Waves rising and falling like walls.
Sukuna keeps you afloat effortlessly, one arm locked around your waist, the other braced against a rock outcropping near the cliff face.
He holds you close to stone where the water is fractionally less violent.
You cling to him, panting, your whole body shaking with cold and adrenaline.
He looks maddeningly composed.
“Breathe.” he says, as if you need instruction.
You manage a choked laugh that turns into another cough.
“I— I am.”
His mouth curls, smug even now.
“Loud.”
You glare weakly and tighten your arms around his neck anyway, because the idea of letting go makes your stomach drop.
Sukuna’s gaze sweeps the island’s dark mass.
Somewhere above, the facility sits unseen.
You know alarms are screaming inside.
You know men are running down halls in a matter of minutes.
You know your name is already being said with anger.
You don’t look back. If you look back, you might freeze.
Sukuna looks down at you.
His eyes are intense, pupils still wide.
He’s beautiful.
He could leave you here.
He could loosen his grip, let you cling to rock, and vanish into the storm-dark ocean like the nightmare the institute painted him as.
He is out, he got you out, he could leave you to your own luck and paint this debt as paid.
Instead, his hold tightens.
“Come.” he says again, voice low near your face.
You blink rain from your lashes.
“Where.”
His gaze shifts toward the far side of the island, toward a darker contour in the water.
“I know.”
You hesitate, breath still ragged.
“It’s far.” but you have nowhere else to go.
He bares teeth, not amused.
“Hold.”
You don’t argue. How could you? You’re too cold, too exhausted, too aware of how much you’ve already given up.
Sukuna dips under the surface with you again, and the storm noise muffles instantly, replaced by the deep, heavy silence of water.
You keep your arms around him. You keep your body tucked close.
He swims.
Minutes stretch into something that feels like forever. Your body fights the cold. Your muscles cramp from clinging. Your throat burns from inhaling salt spray and then holding breath again when he dives deeper to avoid surface turbulence.
Sukuna keeps a rhythm that is brutal and efficient. He surfaces only when necessary, keeping you close enough to breathe. When your lungs start to panic underwater because he doesn’t surface, he presses his mouth to yours again and gives you air with controlled exhalations, not allowing you to spiral into thrashing.
Each time, you’re struck by the strange intimacy of it — the fact that your survival is literally moving between your bodies, that the line between predator and protector has blurred into something you never expected to live.
You don’t have the energy to name it.
You just endure it.
At some point, the water around you shifts, the current changes texture — less violent.
Sheltered.
Sukuna angles upward and breaks the surface again, and this time the wind doesn’t hit you like a slap.
The rain is softer now. The waves are lower.
You find yourself near a different shore — rocky, hidden, tucked into the island’s jagged geometry like a secret mouth.
A narrow cove, half sheltered by stone.
The kind of place boats might not see from open sea.
The kind of place a creature like Sukuna would remember.
He drags you in with relentless strength, hauling you toward a shallow ledge where your hands can finally find rock that doesn’t slide away under you.
You cough, spit salt, and cling to the stone with shaking fingers.
Sukuna surfaces beside you, breathing slow, water streaming off him.
He looks at you like he’s checking inventory.
“Alive.” he says again.
You laugh weakly, then shiver so hard your teeth click.
“Barely.”
His eyes narrow. He shifts closer until his shoulder presses against your side, a solid line of warmth even in cold water. His hand comes to the back of your neck, claws careful, holding you steady against the rock so you don’t slip.
“You are heavy.” he says, as if complaining.
“You dragged me,” you rasp. “You told me to come.”
His mouth curls, a toothy grin.
“Yes.”
You try to lift yourself higher onto the rock but your arms shake. Your legs feel like they belong to someone else.
Sukuna watches you struggle for three seconds, then hooks his arm under your ribs and hauls you up onto the ledge with humiliating ease. You end up half sprawled on wet stone, chest heaving, hair plastered to your face.
The rock is cold against your skin. The air tastes like storm and kelp.
Sukuna remains in the water, half risen, forearms braced on either side of you like he’s caging you again — except there’s no glass now, no artificial tide, no clean line dividing worlds.
You look at him, breath shaking.
“They’ll come.”
He blinks slow.
“Let them.”
“They’ll hunt you.”
He bares teeth, not smiling.
“They tried.”
You swallow. Your body trembles, exhaustion finally catching up.
“And me,” you whisper. “They’ll—”
Sukuna’s gaze locks on yours, sharp and steady.
“You chose.”
“Yes,” you admit. “I did.”
He leans closer.
His forehead brushes yours briefly — an odd, blunt contact that isn’t human affection but isn’t nothing either.
“Then you will survive,” he says, voice low, like an order he expects you to obey. “You will not die here.”
Your throat tightens.
“You really don’t understand why I did it?”
His eyes narrow again, brows furrowing slightly.
“I understand you are stubborn.”
“That’s not—”
He cuts you off.
“You are mine because you chose. And you chose because you care. Humans do stupid things when they care.”
The bluntness of it makes your chest ache and your brain blank.
You close your eyes, not because you’re crying, but because your body needs a second to exist without fighting.
When you open them again, Sukuna is still there, close, watchful. The possessiveness sits on him like it always has, but now it’s mixed with something quieter — the fact he didn’t leave you when he could have.
You lie on wet rock in a hidden cove while the storm rages further out, and you realize you are no longer inside the house.
No more artificial shore.
No more glass line drawn by nervous gods.
Just stone and sea and a creature who should not exist holding you in place like he intends to keep you alive long enough to regret nothing.
Toji learns very young that the Zen'in pod does not raise its young so much as sharpen them.
There is no tenderness in the water where he grows. No indulgence, no patient correction, no body drifting close in sleep just for warmth. The adults move through the sea with the kind of certainty that leaves no room for softness, and the calves born under their watch are expected to keep up or be battered into learning.
Hunger is not a misfortune there.
Hunger is instruction.
If he does not hunt, he does not eat.
It’s as simple as that.
If he cannot hold his own when a larger body slams into him hard enough to rattle bone, then he is rolled under, bitten, shoved away from the kill, and left to swallow the lesson along with seawater.
The pod never says it kindly because they never say anything kindly.
Everything is a correction. Every correction hurts.
He is not the largest calf, not the heaviest, not the most immediately brutal. He is rangier than some, leaner through the middle, long in the limbs even when he is very small and all angles.
That makes him easy to test. Easy to push. Easy to pick apart.
So the older boys do.
The bigger young males ram him in the flank when the adults are feeding, knock him sideways, snap their teeth too close to his face and laugh in clicks and low pulsing calls when he bares his own in return.
The older females are not better. They are merely more efficient. They ignore him until he obstructs something, until he misjudges a current, until he comes too close to a carcass they believe belongs first to them. Then they slap him with their tails or slam shoulder to shoulder and teach him how quickly the world can blacken at the edges if a heavier body wants it enough.
They raise all of them with scarcity and comparison and force. They raise them with teeth bared as lesson and pain as correction.
You keep up or you get dragged. You fight back or you become the shape everyone else sharpens themselves against.
It is not personal.
That is the lie the adults carry in their mouths whenever a juvenile gets bloodied over some scrap of blubber or gets shoved away from the center of the sleeping circle because he wasn’t fast enough, wasn’t clever enough, wasn’t brutal enough to earn space.
Toji hears that lie so often it becomes part of the water.
It’s not personal.
It’s survival.
He grows up hating the difference between those two things.
The first time he learns properly that no one is going to save him, he is still small enough that the older males can slap him aside with a lazy shoulder check and keep moving. There had been fresh kill that day, something large and rich that one of the adults brought down near the edge of a seal rookery. The water was red with it, thick and thrilling, and the whole pod was electric with the promise of feeding. He had darted in too early.
Excited.
Stupid.
Young enough to think proximity might matter more than rank.
A larger body hit him so hard he spun.
Another juvenile laughed. An adult female caught the back of his neck in her teeth — not enough to maim, only enough to make the point — then shoved him deeper, away from the choicest flesh, away from the liver, away from the first hot strips being torn free.
He had swallowed seawater and fury and humiliation in equal measure.
By the time he gets his turn, the best parts are gone. What remains is stringy, ragged, already chilled by the time it reaches him. He eats it anyway because the alternative is watching the others eat and pretending he is above it.
That becomes the rhythm of his youth.
Pain, correction, adaptation.
If he doesn’t hunt, he doesn’t eat. If he doesn’t fight, he loses what he caught. If he doesn’t learn how to read the micro-movements in a rival’s shoulders, the little shift in current that means a strike is coming, the fast cruel intelligence of his own kind, then he becomes easy.
And easy things are consumed.
There is no warmth in the Zen’in pod for weakness.
They do not coddle. They do not soothe. They do not pull him in when his skin is split or when bigger boys gang up on him in the outer currents just to see whether he’ll cry or bleed first.
They watch. Or they don’t. The adults are occupied with territory, with food, with status games so old they may as well be ritual.
The juveniles learn by taking and by having taken from them.
He gets roughed up often enough that his body starts shaping itself around damage. Scars come in pale against dark skin. One across the ribs from Maki when they are both young and mean and she decides she is tired of his face that week. Another near the shoulder where Naobito caught him because Toji dared to keep a chunk of sea lion calf he should have surrendered. Mai once bit his forearm hard enough to leave a crescent of punctures just because she could, just because he was smaller then and because in the Zen’in pod pain distributed down the line like inheritance.
He remembers blood in his mouth early.
He remembers learning not to show it.
The first time he comes back from a failed hunt with nothing in his hands and nothing in his belly, one of the older bulls — scarred across the face, half a fin missing, not his sire but cruel enough to stand in for one — takes the strip of seal he had managed to drag halfway to shelter and tears it from him in front of everyone. Toji had fought for that strip. It had cost him skin and breath and the use of one arm for the better part of a tide.
The older bull swallows it in three bites, looks him dead in the face, and says in the low, cutting dialect of their pod that maybe next time the pup should learn to kill before he tries to eat.
Toji is still small then, but small does not mean stupid.
He learns.
He learns to lunge first, before mockery becomes impact. He learns how long to hold eye contact and when to break it so it reads as calculation rather than fear. He learns that if he cannot beat someone bigger in a straight contest, he can still make the exchange expensive.
A bite in the wrong place. A rush timed against rock. A feigned retreat that turns into a flank hit when the other calf relaxes for half a second.
He learns to hide food. He learns to circle back alone after the pod settles, following the blood-cloud residue of old kills until he can strip some overlooked piece from bone or tear open a carcass that drifted farther than the others bothered to check.
He learns the map of scarcity.
That is what childhood becomes — not a sequence of seasons, not a string of nurturing memories, but a map of where the world denies him and where he can force it to give something back.
The Zen’in pod are mammal eaters. Sea lions. Seals. Porpoises when they are easy. The occasional shark just to prove they can. They move heavy and sure through waters that smell of fat and old blood, and the calves are expected to take to that business like it is inheritance carved into tendon.
He does, eventually.
He has to.
The first seal he kills alone is a mess. He is young enough that the victory shocks him. Older than he should be for a first solitary kill, younger than he wants anyone to know.
He tracks it badly, rushes the final strike, catches too much blubber and not enough throat. The seal screams underwater in a high, hideous burst of sound that he dreams about later.
It twists, kicks, claws at him. He nearly loses it. Nearly loses an eye. Nearly drowns because he is so fixed on not letting go that he forgets for a few seconds to be smart.
But he gets it done.
By the time he drags the body toward deeper water, half his face is bloodied, his chest is heaving, and one shoulder burns with a ragged groove where the seal’s teeth found purchase before he bit through its neck.
He expects praise, or something like it.
What he gets is a glance.
One of the adult females takes one look at the torn carcass, at the waste of meat where his inexperience turned a clean kill into torn ruin, and says only that he took too long.
That is all.
He hates her for years after. Not because she is wrong because she is right, and because he had wanted the rightness to sting less.
He hates all of them and learns from all of them anyway.
Especially the bigger ones.
Especially the old males, the ones broad with age and practice who move through water like entitlement has mass. They bully first because being first is easier when nobody thinks they can touch you. Toji is small for a while, lean and half-starved-looking in the lanky way adolescents often are, but there is something in him even then that doesn’t bend right.
Something mean. Something proud enough to become a problem.
He notices quickly that there are only two ways to survive constant scrutiny — become uninteresting or become dangerous.
Uninteresting is impossible for him.
So dangerous it is.
So he becomes faster.
He becomes meaner.
Mean enough that the older young males start thinking twice about cheap shots if he is already in a foul mood. Mean enough that one cousin loses part of an ear for trying to body him away from a dolphin kill when Toji is fifteen and starving and done waiting his turn. Mean enough that the pod begin speaking about him in the flat, interested tone used for creatures that are becoming dangerous in useful ways.
Respect in the Zen'in pod is not affection.
Respect is space.
Respect is adults no longer assuming they can take from him without giving something up.
Respect is younger calves looking away first.
Respect is being invited into coordinated hunts not because anyone likes him, but because he has become too good to waste and too troublesome to leave unoccupied.
It comes the first time he drops another young male hard enough in the water that the whole cluster goes quiet.
It comes when his body catches up to the violence in him and he stops being easy to throw.
It comes when he learns the timing of pod hunts well enough to slip into openings no one expected him to see, when he drives prey properly, when he stops wasting movement, when adults who once ignored him start calculating with him in the picture instead of around him.
It comes when he becomes more trouble than he is worth.
By adulthood, he has control of himself in the way predators mean control.
Not softness, not restraint for morality’s sake. Precision. He knows what he can do now.
He knows his size is impressive, even among his own kind.
Broad through the shoulders, long and brutal in the line of his body, scarred enough that younger pod members clock the marks and file away the information without daring to ask where most of them came from. He learned to speak with his body before he learned to bother speaking kindly.
He carries himself like threat made flesh because that is the shape that kept him fed.
Still, for all the use he is to the Zen'in pod, he dislikes being slowed by them.
The Zen’in pod works well together. He is not stupid enough to deny that.
Their coordination is excellent when there is a purpose worth sharing — big prey, difficult terrain, opportunities too good to waste. Coordinated hunting has its merits. He knows the pleasure of a clean surround, the satisfaction of watching prey panic in widening circles until the angles close and there is nowhere left to go.
He likes the violence of it.
He likes being very good at it.
He likes the moment a sea lion realizes too late that every way out is already taken.
But hunting with them means splitting the spoils and enduring their company and listening to Naoya talk like his own voice should be enough to substitute skill
It means the old reflexes returning too easily, the ones that make his shoulders brace and his jaw clench because if he brings something down, somebody will act like they helped more than they did.
What he dislikes most is the noise afterward.
The jostling. The endless assertion and petty dominance from idiots who think a successful hunt entitles them to act like kings. He dislikes Naobito’s smug corrections, the patronizing little physical checks from elders who still think of him as something they made instead of something that endured them. He dislikes how Naoya, once old enough to follow the adults on real hunts, seems to believe cruelty is impressive simply because it comes easily to him.
Alone, things are simpler.
Alone, every mistake is his own and every success belongs wholly to him.
So he spends time mapping the ocean beyond the pod’s habitual routes. He learns where seal colonies move with the season, where sea lions rest, where the water runs cold and rich and likely to hide something worth tearing open. He learns the edges of fish-eater territories too, not because he cares much about fish-eaters beyond avoiding stupid conflict, but because boundaries matter in the sea even when no one pretends to own it.
Aggression between pods is rarer than the surface stories suggest.
Not impossible. Not mythical. Just inefficient most of the time.
Pods within their own communities know the cost of making every encounter into a fight, and even fish-eaters and mammal-eaters tend to keep disputes brief unless hunger or pride swells bigger than sense.
Toji knows that. He respects it only as much as he respects weather — enough to plan around it, not enough to worship it.
So Toji hunts alone whenever he can.
He tells himself it is because he is faster that way. Because he prefers his own timing to anyone else’s. Because a solitary body in the water can range farther, map more, note every rookery and migration line and current break without having to listen to anyone else breathe about it. All of that is true.
The rest of the truth is uglier and simpler.
When he hunts alone, nothing belongs to anyone but him.
That is how he meets her.
He is chasing a seal when it happens.
Not one of the slow, fat bastards that drift too long near the surface in lazy weather, but a lean one with enough sense to cut hard toward broken rock the second it realizes what is coming. Toji had already been stalking it for a while, matching the chop of the surface swell, using the angle of light to keep his darker back from telegraphing too much of him. His mood is decent. His stomach is not empty yet, only thinking about becoming so. The seal is healthy, quick, worth the effort.
Then something flashes to his right.
He should ignore it. He knows that the moment he sees it.
Instead he looks.
Just for a second, just for the stupid animal fraction of attention that a body like his should never waste on anything that is not the kill.
Another orca.
Female, by scent and by the cut of her body, though not one he knows. Not Zen'in. Not any of the mammal-eating pods he has mapped in passing. Her lower half is patterned wrong for them, too clean in a way that marks a different diet, a different geography, a different set of habits. Fish-eater, his brain supplies with immediate contempt, and yet the contempt catches because there is nothing flimsy about her.
She is large enough to command notice, sleek rather than bulky, dark hide bright where the white of her markings catches filtered light. Her face is turned toward him, not timid, not defensive. Curious. Assessing. Her eyes are dark blue in a way he dislikes immediately because it suggests depth he has no use for.
Beautiful, he thinks before he can stop it.
The thought annoys him so much that it costs him the seal.
By the time he snaps his focus back, the thing has cut between two shelves of rock and vanished into a crack too narrow for his current angle. He lunges anyway out of pure irritation, clips stone with the side of his shoulder, and loses the last trace of it into kelp and murk.
When he surfaces a minute later, empty-mouthed and in a fouler temper than the failed hunt alone would justify, the female orca is gone.
He spends the next hour trying to recover some dignity by finding easier prey and failing because his mood ruins his timing. He bites at a sea lion and misses the best line. He tracks a juvenile dolphin, loses interest halfway through the chase, and breaks off before it becomes work.
Hunger grows teeth inside him. The water feels too bright. Every flicker of movement at the edge of his vision irritates him because it is never the thing he actually wants.
By the time he turns back toward the deeper route that leads near the Zen'in pod’s favored lair, he is empty-stomached and ready to bite the first living thing that gives him reason.
That is when he runs into her again.
No pod in sight. No escort, no siblings, no lurking adults holding a perimeter. He is alone and she is alone, which means they are both either reckless or capable enough not to need company. He can respect either.
She is waiting near a ridge of dark basalt, half-shadowed by a curtain of colder current. There is a salmon in her hands, already beheaded, blood trailing in a thin ribbon behind her. The sight of fish should not matter much to him. He does not prefer it. He never has. Mammal fat sits heavier and better in his system, leaves him feeling fed rather than merely full.
But hunger is hunger, and the salmon is fresh.
He slows, suspicion tightening everything in him. This could be bait. An insult. A territorial message dressed up in something he can swallow.
She holds the fish out when he draws within striking range.
Just like that. No theatrics. No threat posture. No deferential lowering either. The movement is clean, direct, as if the offering itself is explanation enough.
Toji stares at it.
Then at her.
Then at it again.
His brows draw together. His bad mood makes every possibility feel offensive.
Is she mocking him because she saw the seal get away. Is this some fish-eater’s way of pitying a mammal-hunter. Is this an ambush waiting for him to get close enough to take his attention off the water around them.
She says nothing. Just keeps holding it out, blood trailing over her fingers and dispersing into the current. There is an odd expectancy in her face, not nervousness, not challenge — something nearer to simple certainty that he will take what she offers because why wouldn’t he.
Why wouldn’t he, indeed.
He snatches the salmon out of her hands hard enough that his knuckles brush her skin.
The fish is cold and slick and rich. He tears into it with the irritation of a man chewing through his own bad temper, flesh splitting under his teeth, fat and blood washing over his tongue. It is not seal. It does not need to be. It is food, it is easy, it is there.
She watches him eat.
That bothers him nearly as much as the gift itself.
Not because he is ashamed of hunger — he isn’t. Hunger is the oldest honest thing in him. But because she looks… satisfied. Like his acceptance proves something to her. Like she expected the exact shape of this moment and is pleased to find herself right.
When the salmon is gone, he licks blood from his teeth, looks at her one more time, and leaves.
Not hurriedly. He will not be rushed away from anything by a female who looks at him like a solved problem. He swims off at a steady pace and then circles back twice through darker water to make sure she is not following.
She isn’t.
Odd, odd orca.
He expects that to be the end of it.
It is not.
He sees her again a few days later while mapping seal routes near an offshore shelf where the current bends warm enough to keep mammals lingering longer than they should. He notices her first by the sound of her movement. Fish-eaters travel differently when they are not trying to be silent. More darting adjustments. Less confidence in their weight, even when they are big. He had been ready to ignore it until her scent reached him and memory clicked into place.
She comes into view below him, turning in a slow, easy spiral to match his depth.
Still alone.
That is the first thing he says to her.
“Where is your pod.”
She lifts one shoulder in something dangerously close to amusement.
“Somewhere else.”
Useful answer. He dislikes her at once for the shape of it.
She asks him if the seal got away because he was distracted.
He bares his teeth.
She laughs outright then, water bubbling from her mouth in a way that would sound bright if anything about her felt innocent.
There is sharpness under everything she does, even the generosity.
He should leave.
Instead he stays long enough for her to ask why he hunts alone if he has a pod.
The question is too audacious. Too familiar. It lands right on the seam between things he does not discuss and things no one bothers to care enough to ask.
He sneers first out of reflex. Lets the expression sit on his face long enough that any creature with self-preservation should read it and back away.
She doesn’t.
“I prefer to do shit by myself,” he says at last, because the answer is true and because it costs him nothing to say it like an insult. “Less chance of being slowed down.”
Her mouth curves.
He realizes, belatedly and with irritation, that she is enjoying him.
She keeps asking questions after that, little ones.
Not the kind that dig straight into weakness, which he would understand and answer with violence if needed. Trivial things.
How far he ranges when he scouts. Whether he prefers deep hunts or shoreline ambushes. Whether the scars on his shoulder came from sharks or from other orcas.
When she circles him once to get a better look at the marks along his side, he huffs a stream of water at her face in open annoyance.
“None of your business.”
She blinks salt away from her lashes, chuckles, and says he should join her on a hunt sometime. Maybe he would like company for once.
He tells her he does not eat fish.
She gives him a smug, narrow look that makes him want to bite something.
“You didn’t seem to hate the salmon.”
He bares his teeth at that and sees satisfaction flicker in the set of her shoulders before she winks — actually winks, like a lunatic — and swims away without waiting to see whether he answers.
Odd, odd orca.
They keep meeting.
Not every day. Not on any reliable schedule. But often enough that he starts noticing the spaces where she might appear.
There is a ridge line she favors north of the colder trench. A shallow run where the salmon fatten before the turn upriver. A stretch of open water over volcanic rock where he sometimes patrols seal migration lines because the currents carry scent clean there.
Sometimes he sees her first.
Sometimes she is simply there when he arrives, as if she knew his habits before he had consciously mapped hers.
He is wary the entire time.
The Zen'in pod do not trust cross-pod interactions that are not strictly necessary. Fish-eaters and mammal-eaters do not waste time on romance, not usually, and when they conflict it is brief and pointed and territorial rather than obsessive.
He knows this. He also knows ambushes do not announce themselves. An orca from another pod showing interest in him when he is alone could mean many things, most of them unpleasant.
So he watches for the ambush every time.
It never comes.
What comes instead is irritatingly useful company.
She really knows fish, and not in the lazy way mammal-eaters discuss fallback food when the good prey runs thin, but with the kind of intimate awareness that only comes from shaping your life around migration pulses and spawn-heavy currents. She shows him, without making a grand lecture of it, where the fattest salmon run when the coastal mammals are scarce. She knows the cut of an incoming school by the way the water flickers ahead of it. She knows how to find the places where fish stall in confusion between freshwater pull and open sea salt, where they become easy, heavy food that does not require a long chase.
He files all of it away instantly.
He tells none of it to the Zen'in pod.
That information is his because she gave it to him and because he took it, and those are the only laws that matter to him. He knows exactly what would happen if Naobito or the others learned about the site — they would flood it. Strip it. Claim it as communal.
Pretend his scouting was merely a contribution to shared survival rather than something he earned.
No.
Let them chase their sea lions and bleat about bloodline strength. He has his own routes now.
Still he does not understand her.
She keeps turning up when she doesn’t have to. Keeps talking when he gives her very little to work with. Keeps swimming near enough that he can feel the pressure change her body makes in the water. She circles him while asking about old scars as if the question itself is not insolence. She brushes near enough sometimes that their fins almost align, not touching but close enough that the lack of contact becomes its own kind of pressure.
Any other orca behaving like this would read to him as a challenge. Or a trick.
With her it reads as… something else.
He does not identify it quickly because he has no reason to. No one flirted with him when he was young. Why would they. He had hunger in his eyes and fresh wounds every season and a temperament like open water in a storm.
The Zen'in pod respected him once he became useful, once he became dangerous enough that no one wanted to waste energy testing him lightly.
Respect is not courtship. It never looked like this.
There is no framework in him for a female seeing him and deciding to keep coming closer.
So the months pass with him half-suspicious, half-annoyed, and very aware that he is thinking about her more than he should.
He starts noticing the absence when she doesn’t appear.
That alone nearly makes him angry enough to end it.
Once, while scouting alone near a line of broken reefs where sea lions sometimes haul out, he catches himself looking toward the higher column of water where he first saw her. Looking, not because something moved there, but because his body had learned to expect the possibility.
He stops dead in the current, stares upward at nothing, and feels contempt twist through him so sharply that he bites the first stupid fish that swims too close.
Pathetic.
He tells himself that several times over the next few weeks. Each time, he still keeps meeting her.
By the time he realizes what she has been doing, nearly three months have gone by.
Three months of gifts, information, circling questions, looks held too long, invitations worded just lightly enough to retreat into banter if he rejected them.
Three months of him mistaking persistence for oddity because it never once occurred to him to interpret it as mating interest.
He is embarrassed when the truth finally lands. Not enough to show it. Enough that his next mood is vicious for the better part of a day.
In retrospect, he feels stupid.
Not for missing it, most females don’t flirt in ways he recognizes because most of the females he knows are from the Zen’in pod or those adjacent, and there courtship is a rough thing, tangled up with dominance and rank and acquisition.
It is more obvious. More territorial. Less patient.
This female — this odd, fierce fish-eater with dark blue eyes and a habit of appearing exactly when he has become restless with his own thoughts — does it differently.
She gives him food.
She asks questions she already knows he’ll deflect, just to hear what the deflection sounds like.
She circles him like she’s taking inventory and finds the inventory pleasing.
She keeps inviting him into her routes without ever crowding him into obligation.
She laughs at him and keeps coming back anyway.
The realization comes during another shared hunt.
They are after mammals this time, not fish. She had joined him near a rocky channel where smaller seals sometimes move through in twos and threes, foolish in the warm season and too confident in distance from shore. He had not asked her to come. She had not asked permission. She simply fell into pace beside him and then angled wide on his first approach the way a competent hunter would, herding without being told, cutting escape with clean instinct even though mammal hunts are not supposed to be her specialty.
He notices, mid-chase, that she is not merely helping. She is showing off.
Not in a stupid way. Not the Zen'in kind, all noise and sharp turns and obvious posturing. Hers is subtler. The ease of her turns. The confidence in how close she gets to the prey before she peels off. The way she glances toward him after a well-timed cut as if checking he saw it. Her whole body says look at me in a language he should have understood weeks ago.
By the time the seal is dead and drifting red into the current, Toji is no longer thinking about food.
He is thinking about three months of being an absolute idiot.
She swims beside him afterward, breathing hard but pleased, dark blue eyes brighter than usual. Blood clouds around them in thin dispersing threads.
He looks at her and decides he is done pretending not to understand what is in front of him.
“Are you flirting with me.”
The question is so blunt it almost startles him too.
It absolutely startles her.
For the first time since he met her, she loses control of her face. Her mouth parts. Her gaze jerks away. Her body, so reliably smooth and assured in water, hesitates like she forgot for a second how to hold it.
It is deeply satisfying.
Then the satisfaction turns into something stranger when he realizes she is actually embarrassed.
Yes, he thinks, staring. Good. Serve her right.
She recovers slowly, which pleases him even more because it means the question truly caught her clean. When she looks back at him, there is heat in her face and a tension at the corners of her mouth he has not seen before.
“Yes,” she says at last. Then, after a beat that reads like wounded pride wrapped in honesty: “I have been. For months.”
His brows lift.
She actually looks away again, jaw tightening.
“I thought you just weren’t interested,” she mutters. “Or that maybe you had a mate in your pod.”
That is what makes him laugh.
It bursts out of him hard and ugly and genuine, big enough that he nearly inhales water for it. The idea is so far from reality that it becomes obscene.
Him, with some docile arranged little thing from the Zen'in pod pretending compatibility because bloodline and convenience said so.
Him, wasting his time on some dutiful female who would expect pod politics and shared kills and all the heavy, tedious ritual of official attachment.
He laughs until her irritation starts to rise off her in visible waves.
“You think that’s funny?” she says sharply.
“Yes,” he answers at once, not bothering to soften it.
Her eyes narrow.
“You could just say no.”
“I’m not saying no.”
That stops her too.
He watches the confusion hit, followed closely by suspicion because now it is her turn not to understand the thing in front of her.
“Then why are you laughing.”
He wipes a hand over his mouth and looks at her properly.
“Because you should’ve been straightforward.”
She stares at him as if he has just proposed biting the moon.
“Who is straightforward about flirting and mating?”
“I am.”
“You are not.”
He is already moving by the time the denial leaves her mouth.
There is something almost enjoyable about how quickly she stills when his hands find her hips.
The place where human meets orca in her body is strong under his palms, muscle and slick skin and the subtle give of a predator made for speed rather than blunt force. He wraps both hands there and pulls her in close enough that the current between them disappears. His deep green eyes stay fixed on hers while he crowds her space with the calm certainty of someone who has never needed to ask twice for anything he truly intends to take.
Up close, she smells like salt, fish-oil richness, old river currents, and a darker undernote that has nothing to do with species and everything to do with the fact that she wants him.
Beautiful, he thinks again, and this time the thought annoys him less.
She goes very still, but it is not recoil. It is attention so complete he can feel it in the tension of her waist beneath his hands.
He leans in slowly on purpose.
Not to be gentle. To make her hold it.
Her pupils widen. Her mouth parts. She does not move away.
Good.
He lets his face connect with hers and drags his tongue over the seam of her mouth.
Not a kiss in the soft mammal sense. More test than claim, more taste than tenderness. Salt and the ghost of blood from the finished hunt linger there.
He likes the way her breath catches against his face. Likes the tiny shudder that goes through her hips in his grip when she realizes he is serious.
Then she giggles.
It is a ridiculous sound under the circumstances — light and almost delighted — and because he has no good answer for it, he does the only thing that feels correct.
He does it again, slower.
This time she indulges him. Her mouth opens properly, inviting rather than merely permitting, and he tastes fish and sea and the particular sharpness of her amusement all at once. It does not feel like the first thing he thought it would, which had been conquest, simple and clean. It feels more complicated. More mutual. More like the hunt never really ended, only changed shape.
She pulls back just enough to look at him, still held firm at the hips, and the smugness in her face has returned.
“So you do understand straightforward.”
He bares his teeth at her, because he refuses to let the moment settle into softness.
“You wasted three months.”
“I was being subtle.”
“You were being annoying.”
She laughs again, no trace of shame in it now.
“And yet here you are.”
Here he is indeed — mid-hunt, hands on a female from another pod, with a half-eaten seal drifting nearby and blood still feathering into the current around them.
It is awfully like him.
He looks over her shoulder once out of habit, checks the water, the distances, the lack of witnesses that matter. No immediate pod. No elder eyes. No one to turn this into politics before he decides what he wants from it.
When he looks back, she is watching him with open interest, not timid, not coy, just ready.
He likes that more than he expects.
“You’ll hunt with me again,” he says.
Not a question.
She lifts one brow, almost mocking.
“That’s your idea of courtship.”
“That’s my idea of finding out if I want to keep you around.”
She should be offended if she was sane.
Instead the look she gives him is hot enough to feel.
“Then I suppose,” she says, voice low with the effort of sounding drier than she feels, “you should do a better job convincing me.”
He laughs again, brief and mean, and drags her closer by the hips until their bodies align in the water with nothing accidental left between them.
There is prey still to finish. There is meat to take. There is a route back to the Zen'in pod waiting if he chooses to use it. There are a thousand practical reasons not to begin something here, in open ocean, with blood still fresh and hunger not yet settled.
Toji has never been especially moved by practical reasons once he decides he wants something.
So he stays where he is, holding her steady while the current brushes around them, and lets the hunt change into a different sort of chase altogether.