beneath the murky depths;
octoman sukuna x f!reader
plot: your vulnerable state catches the attention of an oceanic god — themes/warnings: tentacles, smut, monster fucking, orally & in v, painful sex, dubcon — w.c: 1.4k • ao3 • masterlist
a/n: by request, hope this is what you were looking for! <3 keep the warnings in mind before clicking in.
You didn’t mean to fall asleep on the beach, but you couldn’t help it. You were so tired and it was so warm—how could you pass up such an opportunity?
You supposed that the problem was that, when you came around, the shores were now empty and devoid of seemingly everyone. It was dark in such an odd way too, with the skies looking more blood red than the usual dark blue that blanketed over the horizon.
At first, you thought that you were dreaming but the longer that you lay awake, the more real it all seemed. Something in the air tasted bitter, almost metallic—while the ground beneath your body gently trembled—the sand flittering around without a cause. You sat up in a flash, trying to make sense of what you were experiencing, only to be met with the otherworldly sight of what appeared to be rising tides, somehow paused at a standstill.
“What the…?” you murmured to yourself, your voice coming out as a hoarse whisper as it was still thick with sleep.
The waters, so void-like and foreboding, parted at the center like two liquified curtains separating at the seams, giving entry to a tall and imposing figure beyond your comprehension. Your eyes locked onto the impossible sight, taking note of his robust frame adorned with muscles; showcasing four large strong arms sprouting from his body alongside a set of tentacles spearing from his back.
Instinctively, your first course of action was to back away as far as you could, even though it seemed like you had nowhere to run off to. There was a strange feeling of some sort of ambient pressure, like this being’s presence prevented you from moving very far, if even at all.
“You’re a curious thing, aren’t you?” he purred in a deep voice.
You stared at the monster, blinking a couple of times as your mind raced for a potential response. Something like him shouldn’t exist—there was simply no way—and yet… this didn’t seem to be a dream nor a nightmare, so what on earth were you looking at exactly? His face didn’t make sense either, with the parallel half boasting something resembling barnacles with shells alike, peering out what appeared to be another set of eyes.
“W-what are you?” you finally managed to sputter out.
He smiled slightly, yet there was nothing warm about the gesture. “The mortals know me as Sukuna,” he introduced himself, eyeing you down with fixed contempt, “you should be thankful to be in the presence of a god.”
“A-a god?” you replied.
Sukuna hummed, retaining his stoic demeanour, although a hint of arrogance crept into his eyes. “Depends on who you worship, some might call me a demon…” he trailed off, letting the implication linger in the air before continuing, “now, who might you be?”
You just barely muttered out your name to him.
Addressing you personally, he took a step closer, his figure looming over yours, casting a dark shadow over where you were sat. “And what do you offer me?”
You blinked. “H-huh? Offer? I-I didn’t pray to you… d-did I?”
Sukuna rumbled out a low, deep-bellied laugh. Despite his reaction to your confusion, he didn’t seem to be amused in the slightest. “I won’t ask you again,” he warned, addressing you personally once more, “so tell me, what do you offer me?”
“I-I don’t have anything?” you nervously asked.
“Everyone has something to offer,” he corrected you, branching out a finger to tweeze at your chin, tilting your head up to meet with him directly. You froze at the sight, your eyes wide with fear. “How about… your lust?”
Your words failed you for a second before you were able to even respond.
But then you finally managed something, “I…I— What?”
Sukuna hovered over you, his scarlet gaze locking onto yours, daring you to oppose his suggestion. You were too terrified to reject him and ultimately wanted to live through whatever this was, so you found yourself apprehensively nodding in agreement.
“O…kay…” you just barely choked out.
Sukuna didn’t need to be told twice, immediately moving over you. The tentacles that rooted from his back snaked over towards your body, capturing your limbs in a tight, wrapping embrace. You gasped out at the bizarre sensation, feeling the tugging weight of them spread your legs apart while keeping your arms locked in place.
“You should be able to take me after this,” he lazily murmured, coiling a tendril over your now-spread sex, placing a fleshy suction cup just over your clit. The pleasure was immediate as soon as the connection was made, the sucker vacuuming over the bud.
As the motions continued to spread a surging sensation of warmth, a sweeping tingle simmered through your core. Almost instinctively, your body lifted itself to lean into the spike of the muscle, letting slip of needy—almost whining shuddered out whimpers.
“Such an obedient girl,” he almost praised, seeming to approve of your reactions.
There was no time to reply to his condescending flattery as the blissful sensation rose, pushing your body above and beyond its capable threshold. An exhilarating peak formed in between your legs, boiling over to overflowing ecstasy as your eyes rolled back and your toes tingled and curled.
However, it didn’t seem to be over just yet. Sukuna plucked the limb away, guiding it slightly lower to meet at your entrance instead. You were slicker at this point, with your heat glistening in your sopping release. He then speared the tentacle into your sex without warning, impaling you with the tentacle, moving another to swim through your slightly ajar lips, feeling overwhelmed as he simultaneously fucked the tendrils into your body, keeping you perfectly well filled.
Quickly flustered, you unintentionally rolled your hips to match the momentum of how he moved within you, finding that he was able to slowly bulk out the swelling girth of the boneless limbs, leaving you completely stuffed as you were forced to adjust around the size, left perfectly distracted as he slowly eased the feelers out of your body.
Thinking it was over, you wrongfully relaxed, as once again without warning or any chance to recover, Sukuna moved forward in his plan to have you fully take him, positioning the tip of his heavily thick cock into your cunt, pushing himself fully inside.
Regrettably, you weren’t quite as ready as he thought, so he suffered your teeth sinking into one of his tentacles that hovered nearby, seething out a pained hiss in response. Quickly retracting it, however, he half laughed, half scoffed as if amused by your little slip-up. “You’ll take me,” he warned or rather, promised, “and you’ll take me well.”
Once again, he eased himself into your core, his eyes fluttering in pleasure from the sensation of your walls swallowing around his length. Slowly, he drove his cock through you, taking note of how your legs widened out of necessity before settling in as far as he could realistically push.
At first, it felt like a punch to the gut, almost, as he started to move. The thudding impact of him hitting your cervix over and over, was nothing short of excruciating, feeling unlike any other pain you had experienced before. Repeatedly, Sukuna stole your breath away as he rutted into your hilt, his creeping tentacles returning to maneuver around the contours of your body, wrapping himself tightly around you—all the while he slammed himself into your soon battered and bruised apex.
And as you let yourself go, your mind blanked. It felt like your orgasm was closer to killing you, than anything else as he continued to brutally penetrate you. He too, was caught up in an almost violent body-wide rolling shudder—filling you up with the flooding aftermath of his peaking climax—with trickling residue that sept out of the cusp of the tentacles, coating you in a sealing pact of something left unspoken.
Your eyes drooped shut after that, but rather than waking up safe and sound on the beach, praying to something else that this was all part of some bizarre nightmare—you found yourself plunged into the dark waters along with him—unintentionally promising yourself to be kept until the end of time.
After all, Sukuna didn’t quite tell you one little detail of the pact.
An offering was a promise, and a promise was forever.
