Sirius Black x Slytherin!Reader 𝓼𝓸𝓾𝓵𝓶𝓪𝓽𝓮 𝓪𝓾
Summary : When everyone turns sixteen, they get a soulmate mark. Sirius’s appears at midnight — a glowing ⯌ — and the Marauders celebrate with him. The next morning, he proudly shows it off, while across the hall, you nearly choke on your breakfast seeing the same mark hidden under your sleeve. You cover it up fast — no one can know.
Warning : This story contains emotional tension, harsh words, and scenes of heartbreak and self-doubt. It explores themes of soulmates, denial, and the pain of being tied to someone you can’t stand — or maybe can’t stop thinking about.
a/n : lowkey this was so annoying and hard to write because i had no ideas what to do and also sorry if this fic feels very random at some moments idk how to do a pt2 so u need to give me ideas-
The Gryffindor dorm was alive that night — candles flickering low, laughter spilling into the shadows between four-posters, and James Potter counting down every minute like it was Christmas morning. Sirius was sprawled across his bed, pretending he didn’t care, but the restless tapping of his fingers on the blanket gave him away. Sixteen. Tonight, he’d find out if fate had chosen him someone — or no one at all.
Remus glanced over his book, voice soft but teasing. “You’re shaking the bed, Pads.”
“Am not,” Sirius said, though his grin was sharp and a little nervous.
“You kind of are,” Peter piped up, earning a pillow to the face. James was grinning, wide and golden as always, eyes darting between the clock and his best friend.
“Thirty seconds!” he announced, and suddenly it felt like the whole room was holding its breath. Sirius sat up, heart thudding. He wanted to laugh — he wanted to look unbothered — but Merlin, what if he didn’t have one? What if the universe decided Sirius Black didn’t deserve a soulmate?
“Ten!” James shouted, and the Marauders chorused along.
“Nine!” “Eight!” “Seven!”
Sirius’s pulse pounded in his ears. The air buzzed — something electric, almost magical.
Midnight struck. A glow flared across his wrist — faint, gold, and real. Sirius’s breath caught as the light swirled and settled into the shape of a smooth, curved symbol
gleaming faintly before fading into his skin.
For a moment, nobody spoke. Then James whooped so loud it probably woke half the tower. “He’s got one! Bloody hell, Pads, you’ve got one!”
Remus was smiling quietly, Peter clapping excitedly. Sirius just stared at his wrist, mouth slightly open, laughter bubbling up from somewhere deep in his chest. He turned his arm over, tracing the mark like he couldn’t believe it.
“Looks like fate actually likes you,” Remus said softly.
Sirius huffed a laugh, still breathless. “Guess so.”
But later, when the lights dimmed and the others drifted off to sleep, he lay awake — the mark glowing faintly in the moonlight — wondering who in the world his symbol matched, and whether they were out there thinking of him too.
Breakfast the next morning was practically buzzing with gossip. Word had spread fast — Sirius Black had gotten his soulmark. He strolled into the Great Hall with that usual swagger, hair perfect despite the early hour, grin already in place. James and Peter trailed behind him, both barely containing their laughter. Sirius didn’t waste a second; halfway through breakfast, he stood dramatically and rolled up his sleeve. The faint ⯌ shimmered against his wrist, catching the morning light. The reaction was instant — gasps, groans, and even a few dramatic sighs echoing through the hall.
You nearly choked on your toast the moment Sirius rolled up his sleeve. The ⯌ gleamed in the sunlight, clear as day, and your heart just about stopped. You coughed quietly, forcing a calm expression, hoping no one saw the way your hands trembled.
Across the table, Regulus sighed. “Typical. He has to make everything dramatic.”
Barty rolled his eyes, muttering, “He probably practiced that reveal in the mirror.”
You gave a weak laugh, pretending to agree, though your stomach twisted hard.
Under the table, you tugged at your sleeve, just enough to peek. The same symbol shimmered faintly on your wrist
glowing like it knew. You yanked your sleeve down instantly. No. This couldn’t be real. You hadn’t told anyone when it first appeared, and you weren’t going to now. Let Sirius Black have his crowd. The universe clearly had a sick sense of humour.
Sirius had been glowing all day — literally and figuratively. His mark shimmered faintly every time he moved, and he hadn’t stopped smirking since midnight. Still, the excitement was starting to dull under one irritating thought: his soulmate hadn’t revealed themselves yet. He’d half-expected some dramatic moment, someone rushing up to him, sleeve pulled back — but nothing. Just the same old faces and a growing ache of impatience.
He walked through the courtyard with the Marauders, pretending not to notice how everyone else seemed perfectly paired off. James and Lily were laughing about something stupid, heads close, eyes bright. Remus was murmuring to that quiet Hufflepuff boy who’d turned out to be his soulmate, and Peter was lost in thought — probably daydreaming about Sybil Trelawney, the eccentric girl from Beauxbatons who had his mark. Sirius shoved his hands into his pockets, jaw tight.
That’s when they crossed paths with the Slytherins — or as everyone called them, the Skilttes. Regulus walked in the middle, looking perfectly bored as usual, with Barty and Evan on either side, their fingers loosely intertwined, both of them wearing those matching smug smiles that made Sirius want to hex something. And then there was you. The picture-perfect Slytherin princess — sharp uniform, calm smile, eyes that gave nothing away.
Sirius had reached his limit. The constant whispering about soulmates, the glowing marks everywhere, the fact that his hadn’t even shown themselves yet—it was eating at him. So when they crossed paths with the Skiltes again near the courtyard steps, he didn’t even try to stop himself. “Oi, Reggie,” he called, voice dripping with mock cheer. “What symbol did our precious little Black heir get, then?”
Regulus froze for a split second before rolling his eyes, his usual mask slipping into place. “Why do you care?” he muttered, but Sirius just smirked and crossed his arms. The Marauders had stopped behind him, all ears now, eager for some entertainment. After a moment, Regulus sighed dramatically and tugged up his sleeve, revealing a neat ⚚ gleaming faintly on his wrist. “Satisfied?”
James let out a low whistle. “Fitting,” he said. “Looks like something straight off a family crest.” Regulus shot him a withering look while Barty and Evan snickered from behind, clearly enjoying the show. Sirius rolled his eyes, gaze landing on you. “And what about you, princess?” he asked, voice laced with that smug bite only he could pull off.
You didn’t flinch, though your stomach twisted. Slowly, you rolled up your sleeve, showing nothing but smooth skin. “Nothing,” you said coolly.
Sirius’s smirk turned cruel. “Figures. Guess even the universe knew better than to waste a soulmark on you.”
You folded your arms, eyes narrowing. “Better that,” you said, “than being cursed with you as a soulmate. I actually pity whoever got stuck with that.”
oh how you did actually pit yourself
That hit. His grin faltered, just barely. “Or maybe mine just has standards — something you wouldn’t understand.”
You stepped closer, voice dropping low, every word razor-sharp. “Standards? Right. Must be why she hasn’t shown up yet — says a lot about you, doesn’t it? Maybe she knows better than to get tangled with the boy who ruins everything he touches.”
For a moment, nobody spoke. Regulus stared, Barty and Evan exchanged proud glances, and James muttered something about “bloody hell.” Sirius’s jaw clenched, anger flashing in his eyes — but he didn’t reply. He just turned away with a scoff, tossing over his shoulder, “You’d make a great Slytherin, you know that? Cold and heartless.”
You didn’t let him see the way your hands shook as you rolled your sleeve back down. “Better cold,” you muttered, “than stupid.”
That night, back in your dorm, the castle was quiet — too quiet. The green glow from the lake shimmered faintly across the stone walls, and you sat on your bed, knees pulled close, trying to pretend your chest didn’t ache. The argument replayed in your head again and again — Sirius’s voice, sharp and careless, the way his eyes had glinted when he said the universe didn’t think you were worthy of love.
You swallowed hard, pressing your sleeve to your wrist. It still hurt — not the mark, but everything that came with it. You’d been so careful this morning, dabbing foundation over the faint silver glow before leaving the dorm, making sure not even your closest friends would notice. It had worked — no one saw. No one knew that your mark matched his. The boy who hated you since first year. The boy who’d sneered your name like it was poison.
Hot tears slid down your cheeks before you could stop them. You hated this. Hated the mark, hated the fate that tied you to someone who’d rather laugh than look at you. “Of all people,” you whispered, voice breaking, “why him?” The walls didn’t answer. Only the soft, cruel glow of your wrist beneath the makeup did the faint ⯌, mocking you quietly in the dark.
Sirius had never been this restless in his life.
He’d always imagined the day he’d meet his soulmate — loud, dazzling, a perfect story to brag about. He’d imagined a spark, a glance across the room, something dramatic. But two weeks had passed since that mark appeared, that stupid ⯌ shimmering on his wrist like it had something to say — and nothing. Not a single sign.
He tried to brush it off at first, laughing when James joked that maybe his soulmate had taken one look at him and run for the hills. But every night, when the others fell asleep, he’d catch himself tracing the mark with his thumb, half-expecting it to burn or glow or do something. It never did.
“You’re brooding,” James said one morning, plopping down beside him at the Gryffindor table.
Sirius scowled. “I’m thinking.”
“About what?” Remus asked from across the table, voice gentle but curious.
“My soulmate,” Sirius muttered, poking at his toast. “Or the lack of one.”
James’s grin softened a little. “Hey, maybe she’s younger. Maybe she hasn’t even turned sixteen yet.”
Remus nodded. “Could be. Or she’s from another school. You know, Durmstrang, Beauxbatons — the world’s a lot bigger than Hogwarts.”
Sirius groaned. “So what, I’m supposed to wait around while my mystery soulmate learns her symbol?”
Peter snorted into his pumpkin juice, earning himself a glare. “Sorry,” he said quickly, though his grin didn’t fade. “You’re just… not exactly the patient type, Sirius.”
James leaned back in his chair, smirking. “Yeah, mate. You’ve already checked your wrist more times than Lily’s checked her eyeliner.”
That earned him a bread roll to the face.
Still, Sirius couldn’t laugh it off completely. Not this time. Because the truth was, it hurt. Everyone else seemed to have found their match — James and Lily couldn’t stop smiling, Remus was writing poems for that Hufflepuff boy, even Peter wouldn’t shut up about Sybil bloody Trelawney and her “mystical connection.” Meanwhile, Sirius Black, the boy who always had someone’s attention, couldn’t even find the one person the universe had supposedly made for him.
He leaned back against the bench, eyes drifting over the Slytherin table almost unconsciously. Regulus sat there, talking animatedly with Barty and Evan. And beside them—her. You. Laughing softly at something Regulus said, looking so unbothered it made his jaw clench.
For a moment, something flickered in his chest — irritation, curiosity, he couldn’t tell which. He forced himself to look away, muttering under his breath, “She’s probably too busy hexing first-years to care about soulmates anyway.”
Remus caught the tone but didn’t comment. He just said quietly, “You’ll find her, Pads. When it’s time.”
Sirius wanted to believe that. Really, he did. But as he stared down at that damned mark again, he couldn’t shake the feeling that maybe — just maybe — his soulmate already knew who he was.
And wanted nothing to do with him.
If there was one thing Sirius Black was good at, it was pretending.
For the past few days, he’d thrown himself into being loud again — charming, reckless, the boy everyone expected him to be. If his soulmate wasn’t going to show up, fine. He’d go back to what he knew best: smiling too wide, laughing too loud, flirting with anyone who so much as glanced his way.
You’d seen him that morning outside the Great Hall, leaning against the doorway, a Ravenclaw girl giggling beside him. His signature smirk was back, casual and bright, and his friends were cheering him on from behind like it was all perfectly normal. To everyone else, it was normal. Sirius Black flirting was just another day at Hogwarts.
You paused mid-step, tray in hand, pretending to adjust your sleeve while watching him from the corner of your eye. The way he tilted his head, the way she blushed — it made your stomach twist, though you told yourself it was just annoyance. Of course Sirius couldn’t go a week without attention. Of course he had to act like the universe hadn’t tied him to someone he couldn’t stand.
He laughed then — that stupid, careless laugh — and it was louder than it needed to be. You rolled your eyes and muttered under your breath, “Pathetic.”
Regulus, walking beside you, raised a brow. “Who?”
You blinked, forcing a calm smile. “No one.”
You walked off before he could ask again, ignoring the heat that had crept up your neck. You had better things to think about. Better things than Sirius Black and the way he made pretending look so easy.
The afternoon sunlight spilled golden across the Hogwarts grounds, the lake glittering like glass. Students had scattered everywhere — sprawled under trees, dipping their feet in the shallows, laughing over shared snacks. It was one of those rare weekends when professors gave up on trying to control chaos and just let everyone breathe.
You were stretched out on the grass near the water’s edge, shoes off, robes discarded in a neat pile beside you. Regulus lay on his stomach nearby, doodling lazy constellations in the dirt with his wand while Barty and Evan argued about whose soulmate bond was “stronger.” You rolled your eyes and threw a blade of grass at them, earning a dramatic gasp from Barty.
Across the field, the Marauders were gathered under an oak tree — James and Lily tossing crumbs to the giant squid, Remus pretending to read while Peter snored beside him, and Sirius sprawled on his back, one arm flung over his eyes. You could hear their laughter drifting on the breeze — warm, careless, alive.
It was strange, how quiet everything felt. No insults, no hexes flying between houses. Just this odd, suspended peace. Even Sirius didn’t look like the loud, smug boy who always had something to say; for once, he just looked… calm. The wind toyed with his hair, sunlight catching on the faint silver mark on his wrist — that same damned ⯌ you’d seen in your mirror a hundred times.
You tore your gaze away, heart twisting.
“Stop staring at him,” Regulus murmured without looking up. “You’ll give yourself wrinkles.”
You scoffed and flicked another blade of grass at him. “Wasn’t staring.”
“Sure you weren’t,” he said, smirking. “And I’m not related to that idiot over there either.”
Across the way, Sirius laughed at something James said — loud and free, like he had no idea how cruel the world could be. You forced yourself to look back at the lake, pretending the sunlight didn’t sting your eyes.
The lake glimmered lazily under the afternoon sun, the air thick with laughter and the faint smell of grass. Around him, the Marauders were scattered in their usual sprawl — James and Lily arguing playfully about who could skip stones farther, Peter half-asleep in the grass, and Remus trying to read despite James’s constant interruptions.
Sirius sat a little apart from them, legs stretched out, wand twirling idly between his fingers. From a distance, he looked fine — relaxed, easy smile, sunlight catching on the silver ⯌ on his wrist. But inside, he was unraveling.
Flirting, joking, pretending.
He’d told himself he didn’t care — that maybe his soulmate wasn’t even at Hogwarts, that it didn’t matter anyway. But it was hard to believe that when everyone else around him seemed to have found their match.
Remus’s soft laughter with that Hufflepuff boy. James’s fingers brushing Lily’s as they passed the last stone. Even bloody Peter had his name scrawled inside Sybil’s dramatic letters. And Sirius? He had a mark and no one to match it.
He glanced down at it again — that cruel little symbol, shining faintly against his skin — and his stomach twisted.
What if you’d been right? What if his soulmate really was avoiding him?
The thought hit like a curse. It made sense, didn’t it? He’d been an ass to half the people in this castle — loud, proud, reckless. Maybe whoever was meant for him had seen the mark, recognized it, and decided he wasn’t worth it. Maybe she’d looked at him and thought, not him.
The idea made his chest ache.
“Oi, Pads,” James called, tossing a pebble that landed near his shoe. “You look like you just found out Snape’s your soulmate.”
Sirius forced a laugh, shaking his head. “Just thinking, mate. Dangerous hobby, I know.”
You tossed a pebble into the lake, watching it skip twice before sinking. The water was cool against your legs, the sunlight warm on your skin. For once, it felt like the world wasn’t spinning too fast — laughter echoed from every direction, and even the Slytherins seemed lighter today.
Barty plopped down beside you, nearly splashing water onto your robes. “Merlin’s beard, Y/N, I almost slipped! You’d have to save me.”
You smirked. “Please. I’d let the giant squid handle that.”
Evan snorted behind you. “You’re heartless.”
“Efficient,” you corrected, kicking a little wave toward them.
A few feet away, the Marauders were making their way down the hill, voices loud and familiar. James was grinning like always, Lily swatting him with a folded bit of parchment, while Remus and Peter trailed behind with that “here we go again” look. And, of course, Sirius — hair wind-tossed, hands shoved in his pockets, acting like the sun rose for him.
You rolled your eyes before you could stop yourself.
“Careful,” Regulus muttered, sitting down beside you. “He might think you’re admiring him.”
You nudged him with your shoulder. “Over my dead body.”
By the time the Marauders reached the shore, the Slytherins had already braced themselves. James gave a mock salute, Sirius smirked, and Remus sighed the sigh of a man who knew he’d be cleaning up chaos soon.
“Well, well,” James called, grinning. “Didn’t know snakes could enjoy sunlight. I thought you all hissed at it.”
Barty gasped dramatically. “And I didn’t know lions could count past ten.”
Evan laughed so hard he almost fell back into the grass. Lily groaned, muttering something about “boys and their house pride.”
Sirius leaned lazily against a nearby rock, eyes flicking briefly to you before he smirked. “Careful, Snakes. Wouldn’t want to get your robes dirty out here in the wild.”
You gave him a sweet, poisonous smile. “Please, Black. I’ve seen you fall off your broom more times than I’ve washed these.”
“Ouch,” James said, feigning a wince. “Straight to the ego.”
“Wouldn’t be the first time,” Remus murmured, half-hiding his grin.
You turned back to the lake, pretending the sight of Sirius’s grin didn’t do something strange to your chest. For a second, the laughter around you blurred into background noise — just the water, the sunlight, and the ache you couldn’t name.
“Oi, someone dare Y/N to do something stupid,” Barty called suddenly, his grin too wide to mean anything good. You groaned, not even bothering to look up. “No. Absolutely not. Not again.”
“Oh, come on,” Evan said, flicking a pebble into the water. “Last time was funny.” “You made me hex my shoes together,” you shot back. Regulus smirked from beside you. “You did faceplant into a staircase after that.”
“That was your fault,” you muttered, though you were fighting a smile. Sirius stretched out on the grass, sunlight catching in his hair. You stood, brushing the grass from your robes. “I’m leaving before your stupidity spreads.”
You turned to go — but the grass near the edge was damp, slick from the lake. One wrong step and your foot slipped. You barely had time to yelp before the world tilted and you plunged straight into the water with a splash.
The lake erupted with laughter. Sirius, being closest, instinctively reached out — but instead of saving yourself , you caught his wrist and yanked. He stumbled forward with a curse, losing balance and crashing right in after you.
For a second, there was only chaos — splashing, shouting, everyone howling with laughter. You came up sputtering, hair plastered to your face, Sirius beside you, eyes wide and dripping.
“Real smooth, princess,” he said between laughs.
“Shut up,” you hissed, splashing him right in the face.
James and Regulus were already getting up, still laughing. “We’ll grab towels!” James called. “Food,” Barty added, waving a hand as he and Evan wandered off toward the castle.
Remus barely looked up from where he was sitting with his boyfriend under the tree, both of them lost in quiet conversation. Lily was helping Peter write a letter nearby, the two of them pretending not to notice the chaos at all.
You were still laughing, completely forgetting that you were soaked from head to toe. The grass squished beneath your hands, the lake water dripping down your arms, but you couldn’t stop — it was too funny, too ridiculous.
Beside you, Sirius pushed his wet hair back with a sigh, shaking his head. “Merlin, you’re impossible,” he muttered, but there was a hint of a smile tugging at his lips.
He stood up first, water streaming off him as he ran a hand through his hair, the sun catching on the droplets. You stayed where you were, still giggling softly.
He sighed, then held out his hand. “Come on,” he said, half teasing, half tired.
You blinked up at him, still catching your breath from laughing, before slipping your hand into his. The moment your fingers touched, the warmth startled you — but you brushed it off, letting him pull you to your feet.
As you stood, your sleeve rolled up slightly, and the water soaking through your clothes had done its damage — the foundation had completely washed away. The ⯌ on your wrist shimmered faintly under the sunlight, clear and undeniable.
You didn’t even notice. You were too busy brushing grass off your robes, muttering about how cold the lake was. But Sirius froze, eyes locked on your wrist, breath catching in his throat.
The laughter around him blurred into nothing. All he could see was that mark — his mark — glowing softly on your skin.
James and Regulus came trudging down the slope, arms full of towels, both still laughing about something. Behind them, Barty and Evan followed with a couple of food boxes they’d managed to charm from the kitchens.
He blurts it out before he can stop himself — “Y/N… your wrist…”
You look down, freeze, and realize what he’s staring at. The smudge of foundation is gone — and there it is, the mark you’ve hidden for months. The one that ties you to everything you’ve tried to run from.
The laughter dies immediately.
Regulus’s eyes widen, recognition flickering like lightning. Evan and Barty exchange a look — that mix of curiosity and unease. Even Remus’s conversation trails off mid-sentence, his smile faltering. The entire world seems to narrow down to the space between Sirius and you.
You can feel his gaze — confused, a little betrayed, and something else. Something that makes your throat burn.
You yank your sleeve down. “No. You’re wrong,” you mutter, voice sharp but trembling. You don’t wait for the look on Sirius’s face to change — don’t wait for the questions that will come, or for James’s worried voice. You turn and storm off, heart hammering so loud it drowns out the world.
The mark burns beneath the wet fabric as you walk — and for a second, you almost hate Sirius for noticing. For seeing you when you’ve spent weeks trying to be unseen.
But the worst part — the part that sticks — is the look he gave you before you left. Because he’s given you every reason not to trust him with something like this. Every smirk, every jab, every cruel little joke that made your walls thicker and your smile faker.
The path where you’d gone quieted the world — and then James’s voice cut through it like a knife. “WTF?!” The single word made everyone snap to attention, heads turning, towels and food forgotten in their hands.
Regulus was the first to actually look shaken, his usual smirk wiped clean. He stared at the spot you’d been standing and then at Sirius with an expression that was half disbelief, half something like worry. “No… that can’t be,” he breathed.
Evan and Barty exchanged a look that went from teasing to stunned in a heartbeat. Barty’s grin vanished; Evan’s face went slack. “She… that was her mark?” Barty asked, as if saying it out loud might make it less real.
Sirius stood rooted, towel hanging limply from one hand, water still dripping off his hair. He swallowed like he’d been kicked. “Yeah,” he said finally, too quiet for the circle of noise to reach him properly. “The mark. On her wrist. Everyone saw it.” His voice broke near the end and nobody could pretend they hadn’t heard.
Remus pushed himself up, whole posture suddenly alert and serious. He looked between Sirius and the path you’d taken, jaw tight. “We shouldn’t—” he started, then stopped, because none of them had a plan for this exact kind of mess.
Lily’s face went white but soft with concern; James’s hands curled around a towel like he was ready to throw it at someone. Peter fumbled with his parchment, eyes wide and useless. For a second the only sound was the lake tapping the shore, and over it all the group’s collective breath caught.
The air that followed was heavy and raw. Conversations stuttered into silence. Jokes that might have landed yesterday died in throats. Everyone who’d been laughing a moment before now felt like witnesses to something fragile and terrible — and all of them, whether they wanted to admit it or not, knew the rules of whatever fate had just unspooled.
Sirius finally let the towel slip from his fingers and sink to his sides. He didn’t know what to do next; none of them did. The only thing he felt certain of was that the lake, the sun, even the chatter — all of it had shifted. Nothing would slide back into ordinary after that.
