Archive of Our Own

Katsuki pushes through the crowd toward the bathroom, shoulders turning sideways to slip between clusters of people holding red cups, their conversations bleeding together into white noise he doesn’t bother parsing. Someone’s laughing too loud near the kitchen. Shouto’s birthday cake sits half-demolished on the counter, frosting smeared across the serving plate.

The bathroom door gives under his palm and he steps inside, reaching back to push it closed behind him.

It doesn’t close.

Izuku’s hand catches the edge before the latch clicks, his palm flat against the wood, and Katsuki registers the solid weight of him filling the doorframe before his brain catches up to what’s happening. Izuku steps inside and the door swings shut behind him, the lock turning with a quiet snick that lands in Katsuki’s stomach like a stone dropping.

“Get out,” Katsuki says, the words coming out flat. He doesn’t turn around, keeps his eyes on the sink instead, on the water spots dotting the chrome faucet. “I’m not doing this.”

“You’ve been ignoring me all night.”

Izuku’s voice comes from too close behind him, close enough that Katsuki can feel the heat of him without any actual contact, and his shoulders pull tight in response. He grips the edge of the sink, the porcelain cool and solid under his palms.

“Yeah, no shit,” Katsuki says. “Because we’re at Shouto’s fucking birthday party and you need to learn how to act normal for five consecutive hours.”

“I am acting normal.”

“You followed me into the bathroom.”

“You walked away mid-conversation.”

Katsuki’s jaw clenches, his teeth grinding together hard enough that the pressure radiates up into his temples. He still hasn’t turned around. The mirror in front of him reflects his own face back at him, the flush already starting to climb his neck visible even in the shitty bathroom lighting, and he watches Izuku’s shape move in the background, a dark blur that resolves into sharper focus as he steps closer.

“I walked away,” Katsuki says, forcing the words out through his locked jaw, “because Mina asked if we were dating and you looked at me like you wanted to make a scene.”

“I didn’t say anything.”

“You didn’t have to.” Katsuki’s grip on the sink tightens until his knuckles go white. His reflection stares back at him, eyes hard, mouth pressed into a thin line that doesn’t quite hide the way his breathing has gone shallow. “Your face said plenty.”

“You’re paranoid.”

“I’m realistic.” His jaw clenches tighter, the muscle jumping under his skin. “We can’t just—”

Izuku’s hands land on his hips from behind, the contact sudden enough that Katsuki’s spine jerks straight in response.

“Don’t—” Katsuki tries to twist away but Izuku’s grip tightens, fingers digging into the flesh just above his hip bones, holding him in place. “Izuku, I’m serious. We can’t do this here.”

“You’re always serious.” Izuku’s thumbs press into the small of his back, just above his belt, the pressure steady and specific. “That’s the problem.”

“The problem,” Katsuki bites out, his voice rising before he catches it and forces it back down to something closer to a whisper, “is that you can’t keep your hands to yourself in public. We’re at a birthday party. There are twenty people outside that door. Shouto’s probably wondering where the fuck we both went.”

“Let him wonder.”

Izuku’s hands grip Katsuki’s hips and spin him around, pulling him away from the sink, and Katsuki’s back hits the door with a dull thud that he feels through his shoulder blades. His hands come up automatically, palms landing flat against Izuku’s chest, ready to push him back.

Izuku kisses him before he can.

His mouth lands hot and demanding, lips parting Katsuki’s with enough pressure that Katsuki’s head tilts back against the door, his jaw opening on reflex. Izuku’s tongue slides into his mouth, licking along his teeth and then deeper, and Katsuki makes a sound in the back of his throat that comes out muffled against Izuku’s lips. His hands are still pressed to Izuku’s chest, fingers curling into the fabric of his shirt, caught between pushing him away and pulling him closer.

Izuku decides for him. His hands slide from Katsuki’s hips around to his ass, palms cupping the muscle through his jeans and squeezing hard enough that Katsuki’s hips jerk forward in response. The kiss breaks for half a second while Katsuki tries to get his breathing under control, his chest heaving, and Izuku uses the gap to drag his mouth along Katsuki’s jaw, teeth scraping the hinge.

“Izuku,” Katsuki manages, his voice coming out wrecked already, thin and strained. “We can’t—”

Izuku’s hands slide down, fingers hooking under the waistband of Katsuki’s jeans from behind, and then he’s pushing his palms down into the back of Katsuki’s pants. The jeans are still buttoned, still zipped, tight enough that Izuku has to work his hands down past the resistance of the denim, his knuckles dragging against Katsuki’s lower back as he forces his way deeper.

“Stop,” Katsuki says, but his hands have fisted in Izuku’s shirt now, knuckles white where they’re twisted in the fabric, holding on instead of pushing away. “Someone’s going to hear, someone’s going to—”

Izuku’s fingers find the edge of his underwear and slide beneath the elastic.

The first touch of skin on skin makes Katsuki’s breath stutter in his chest, his whole body going rigid against the door. Izuku’s hands are warm, his palms sliding down over the curve of Katsuki’s ass and then lower, reaching between his legs from behind. His fingers press against the fabric of Katsuki’s underwear where it’s already damp, the cotton clinging to him, and Katsuki feels the exact moment Izuku registers how wet he is through the thin barrier.

Izuku makes a sound against Katsuki’s throat, something low and satisfied, and his fingers press harder, rubbing in slow circles over the fabric. The pressure grinds the wet cotton against Katsuki’s cunt, the friction indirect but relentless, and Katsuki’s hips push forward before he can stop them, his body chasing the contact even as his brain screams at him to pull away.

“You’re so wet already,” Izuku says against his ear, his breath hot on Katsuki’s skin. “Just from arguing with me.”

“Shut up,” Katsuki bites out, his fingers tightening in Izuku’s shirt until his knuckles ache. “That’s not—”

Izuku’s fingers drag up through the soaked fabric, tracing the shape of Katsuki’s cunt through his underwear, finding where he’s swollen and sensitive and pressing down with deliberate pressure. Katsuki’s head tips back against the door, his mouth falling open on a gasp he barely manages to swallow before it turns into something louder.

The music outside pounds through the wood at his back, the bass line vibrating against his spine, and Katsuki fixates on it instead of the way Izuku’s fingers are working over his clothed pussy, rubbing in tight circles that make the wet fabric cling and drag against oversensitive skin. His thighs are shaking already, his knees trying to give out, and he has to lock them straight to keep himself upright against the door.

“We’re at Shouto’s party,” Katsuki tries again, his voice breaking on the last word. “This is— fuck— this is insane, you can’t just—”

Izuku hooks his fingers under the edge of Katsuki’s underwear and pulls the fabric aside.

The first direct touch of Izuku’s fingers against his bare cunt makes Katsuki’s entire body jerk, his spine arching away from the door, his hips pushing back into the contact before his brain catches up to what his body is doing. Izuku’s fingers slide through the slick that’s gathered there, coating his fingertips, and then he’s pressing inside without warning.

Two fingers, straight to the second knuckle in one smooth thrust that punches the air out of Katsuki’s lungs.

The stretch hits him all at once, his inner walls clamping down around the intrusion, his body trying to accommodate the sudden fullness. Izuku doesn’t give him time to adjust. He pulls his fingers almost all the way out, the drag slow and deliberate against Katsuki’s front wall, and then slams them back in hard enough that Katsuki has to bite down on his tongue to keep from making a sound.

“Fuck,” Katsuki manages, his voice barely a whisper, one hand flying up to cover his mouth. His palm presses against his lips, fingers digging into his own cheek, trying to physically hold the sounds in. “Izuku, you need to— we can’t—”

Izuku fucks into him harder, his fingers pistoning in and out with brutal efficiency, the wet sound of it obscene in the quiet bathroom. Each thrust drives deep, his fingertips curling on the withdrawal to drag against the spot inside that makes Katsuki’s vision white out at the edges. His other hand is still twisted in Izuku’s shirt, knuckles white, holding on like it’s the only thing keeping him upright.

His jeans are still buttoned, still zipped, the denim pulled tight across his hips and restricting the movement of Izuku’s wrist where it’s jammed down the back of his pants. The constraint makes every thrust feel deeper somehow, more confined, Izuku’s fingers having to work harder to drive into him at this angle.

Katsuki’s thighs are shaking, his knees threatening to give out, and he has to lock them straight to keep himself standing. The music outside is still pounding through the door, the bass line covering most of the wet sounds of Izuku’s fingers working inside him, but not all of it. Not the desperate little gasps Katsuki keeps making against his palm, not the slick slide of skin on skin.

Three sharp knocks land against the door at Katsuki’s back.

His whole body goes rigid, his breath stopping in his chest, his hand clamping down harder over his mouth. Izuku’s fingers are still buried inside him, knuckle-deep, and for one frozen second everything stops.

“Anyone in there?” A voice filters through the wood, muffled but clear enough. Male. Unfamiliar.

Izuku’s fingers pull back and slam in again, harder than before, and Katsuki’s eyes fly open wide, his free hand scrabbling against the door for purchase. His palm squeaks against the painted wood, his nails catching on nothing.

“Yeah,” Izuku calls out, his voice steady and casual, like he’s not currently finger-fucking Katsuki against the bathroom door. “Occupied.”

“Oh, shit, sorry man.” The voice sounds embarrassed, already retreating. Footsteps fade away down the hall.

Izuku doesn’t slow down. If anything, his fingers drive in deeper, the angle shifting as he adjusts his wrist, and Katsuki has to bite down on his own palm to keep from crying out. His teeth dig into the flesh, the pain sharp enough to ground him, to give him something to focus on besides the relentless thrust of Izuku’s fingers inside him.

The stretch is bordering on too much now, his body struggling to take the pace Izuku is setting, each withdrawal dragging against oversensitive tissue and each thrust punching deep enough that he feels it in his lower belly. His cunt is clenching rhythmically around Izuku’s fingers, his body chasing the stimulation even as his mind screams at him that someone just knocked, someone just heard Izuku’s voice and knows he’s in here.

Izuku’s thumb finds his clit and presses down hard.

The pressure is sudden and direct, no build-up, just blunt force applied exactly where Katsuki is most sensitive. His hips jerk forward violently, his whole body trying to escape the sensation and push into it at the same time, and the sound that tears out of him gets muffled against his palm but only barely.

“They’re gone,” Izuku says against his ear, his breath hot on Katsuki’s skin. His fingers don’t stop, don’t slow, still driving into Katsuki’s cunt with the same brutal rhythm. “You can be louder now.”

“Fuck you,” Katsuki gasps out, his voice wrecked, the words barely intelligible around his hand. His legs are trembling so hard he can feel the vibration traveling up through his hips and into his spine. “Fuck you, fuck you, someone’s gonna— they’re gonna figure out—”

Izuku curls his fingers on the next thrust, dragging directly against Katsuki’s front wall, and Katsuki’s sentence dissolves into a choked-off moan that he barely manages to swallow. His free hand is still fisted in Izuku’s shirt, pulling so hard the fabric is stretching, and his hips are rocking back now, grinding down onto Izuku’s fingers with each thrust, meeting him halfway despite every logical part of his brain screaming at him to stop.

Then he shoves Izuku back hard enough that Izuku’s fingers slip out of him.

The sudden emptiness makes him gasp, his body clenching around nothing, and he uses the momentum to push himself fully upright against the door. His hand drops from his mouth, his breathing coming in harsh pants that he can’t quite control, and he glares at Izuku with enough force that it should burn.

“You answered the fucking door,” Katsuki bites out, his voice low and furious. “While you were— while your fingers were—” He cuts himself off, his jaw clenching so hard his teeth grind together. “What the fuck is wrong with you?”

Izuku’s head tilts to the side, his expression maddeningly calm, his fingers still glistening with Katsuki’s slick. He doesn’t wipe them off. Just stands there, close enough that Katsuki can feel the heat radiating off him, his eyes dark and fixed on Katsuki’s face.

“I’ll calm down,” Izuku says, his voice steady and reasonable in a way that makes Katsuki want to punch him, “if you let me eat you out. Just this once.”

Katsuki stares at him. His chest is still heaving, his pulse hammering in his throat, his cunt still throbbing from the sudden absence of Izuku’s fingers. The audacity of the statement lands somewhere between infuriating and absurd, and for a moment he can’t find words that adequately express how insane Izuku is being.

“Just this once,” he repeats flatly, his eyes narrowing. “Like you haven’t said that before.”

Izuku’s mouth curves into something that’s not quite a smile. He doesn’t deny it.

Katsuki looks at him for a long moment, taking in the way Izuku is standing there all patient expectation, like he’s already won this argument and is just waiting for Katsuki to catch up. His shirt is wrinkled where Katsuki’s fist was twisted in it. His lips are still slightly swollen from the kiss. His fingers are still wet.

The annoyed sound that leaves Katsuki’s throat comes out more like a growl.

“Sit,” he says, jerking his chin toward the toilet. His voice has gone flat, resignation settling into his bones alongside the frustration. “And you’re going to behave for the rest of the party. No touching, no looks, no anything. We go back out there and act normal.”

Izuku moves immediately, backing up toward the toilet and lowering himself onto the closed lid. His hands rest on his thighs, his posture open and cooperative in a way that would be convincing if Katsuki didn’t know him better.

“I swear,” Izuku says, his eyes never leaving Katsuki’s face. “I’ll be good.”

The way he says it makes it sound like a promise he has no intention of keeping, but Katsuki is too worked up and too far gone to care about negotiating better terms. His jeans are still buttoned, still zipped, the denim uncomfortable where it’s pulled tight across his hips, and his underwear is twisted to the side where Izuku pulled it away from his cunt.

He reaches down and pops the button open, the zipper following with a quiet rasp of metal teeth. The relief is immediate, the pressure easing as the fabric loosens around his waist.

The first contact is warm and wet, his lips pressing against the outer fold before his tongue follows, dragging up through the center in one slow deliberate stripe. Katsuki’s breath leaves him in a rush, his fingers curling against the door hard enough that his nails scrape against the paint, and he bites down on the inside of his cheek to keep the sound that wants to escape trapped behind his teeth.

Izuku’s tongue works through his folds in careful passes, learning the shape of him, the flat of it spreading him open before the tip traces the inner edge and dips lower. Each stroke pushes deeper than the last, collecting the wetness that’s already started to gather there and spreading it over sensitive skin, and Katsuki can feel his body responding without permission, his walls fluttering around nothing and his clit starting to swell where Izuku’s tongue keeps brushing past it.

He can hear people laughing in the hallway outside, footsteps passing by the door, someone calling Shouto’s name from the living room. The music shifts to something with a heavier beat and the bass makes the door vibrate under his palms, the tremor traveling up his arms and into his shoulders where they’re locked to keep him upright.

Izuku’s tongue circles his clit once, light and teasing, before pressing down with steady firm pressure, and Katsuki’s hips jerk forward before he can stop them, his forehead dropping to rest against the door. The wood is cool against his skin where his face has gone hot, sweat starting to prickle along his hairline.

“Izuku,” he manages, his voice coming out rougher than he means it to. “Someone’s gonna—”

Izuku’s tongue pushes inside him.

The intrusion is sudden and slick, his tongue breaching the first ring of muscle and stroking the inner walls in shallow pumps, and Katsuki’s mouth falls open on a gasp he barely manages to swallow. His walls clench around the intrusion reflexively, trying to pull Izuku deeper, and the wet sound of it is obscene in the small bathroom, loud enough that Katsuki’s face burns hotter with the evidence of what his body’s doing.

Izuku works him open with patient thoroughness, his tongue curling inside on each stroke to drag against the front wall before withdrawing and pushing back in, his hands still gripping Katsuki’s ass to keep him spread and held exactly where he wants him. The angle makes everything more intense, the position forcing Katsuki’s hips to tilt back and giving Izuku deeper access than he’d have any other way, and Katsuki can feel the pressure building low in his pelvis, the tension winding tighter with each pass of Izuku’s tongue.

His thighs are shaking badly now, the muscles jumping visibly beneath the skin where they’re trying to hold his weight, and his breathing has gone ragged and uneven, each inhale catching somewhere in his chest before stuttering out again. The edge is coming up fast, faster than it should, his body already wound tight from the awareness of where they are and who’s on the other side of the door and what will happen if someone realizes they’re both missing.

Izuku’s tongue drags out of him and moves up to his clit, circling the swollen bud once before sealing his lips around it and sucking.

The orgasm hits him sudden and total, his whole body clamping down around the absence of Izuku’s tongue as his cunt pulses in hard rhythmic contractions. He bites down on his hand to muffle the sound that tries to tear out of his throat, his teeth sinking into the flesh hard enough to leave marks, and his vision goes white at the edges for a few seconds before his brain catches up to what just happened.

His forehead stays pressed to the door while he tries to catch his breath, his chest heaving against his ribs, and he can feel the wetness on his thighs now, slick and cooling in the bathroom air.

“Okay,” he manages after a few seconds, his voice coming out wrecked and shaky. “Okay, that’s—we need to go back now, someone’s gonna notice—”

Izuku doesn’t stop.

His mouth stays pressed against Katsuki’s cunt, tongue already moving again in slow patient circles over his oversensitive clit, and Katsuki’s whole body jolts at the contact, his spine snapping taut.

“Too much,” Katsuki gasps out, his hand reaching back to try and push at Izuku’s head, but Izuku catches his wrist and pins it against the small of his back, holding him in place. “Izuku, I already— you said you’d—”

Izuku’s tongue flattens against him, dragging up through his folds in one long slow lick that makes Katsuki’s knees buckle. He has to lock them straight again to stay upright, his other palm pressed so hard against the door that his fingers are starting to ache.

The second pass of Izuku’s tongue is slower, more deliberate, like he has all the time in the world and intends to use it. He traces the outer edge of Katsuki’s entrance with the tip, circling the rim in teasing passes that make Katsuki’s walls clench around nothing, before dipping just barely inside and withdrawing again. The sensation is maddening, too light to satisfy and too much to ignore, and Katsuki can feel his body starting to build toward something again despite the fact that he just came.

Izuku makes a sound against him, low and satisfied, and Katsuki feels the vibration travel through his pelvis and up into his lower belly. His tongue moves with unhurried precision, alternating between broad strokes through Katsuki’s folds and focused attention on his clit, never quite settling into a rhythm that Katsuki can anticipate. Each touch lands with deliberate care, Izuku learning what makes Katsuki’s breathing hitch and what makes his thighs shake harder, cataloging the responses and using them.

His lips close around Katsuki’s clit again, not sucking this time but just holding the pressure, his tongue flicking against the sensitive underside in quick light pulses that make Katsuki’s hips try to jerk away. Izuku’s hands tighten on his ass, thumbs digging into the muscle to keep him exactly where he is, and Katsuki realizes with a sinking sensation in his gut that Izuku isn’t trying to get him off quickly so they can leave.

He’s taking his time. He’s enjoying this.

The thought makes something hot and uncomfortable twist in Katsuki’s chest, embarrassment mixing with arousal in a way that makes his face burn hotter. He can feel Izuku’s breath against his inner thighs where the skin has gone damp with sweat and slick, can feel the way Izuku’s tongue keeps returning to trace the same paths over and over like he’s memorizing the shape of Katsuki’s cunt.

Izuku’s tongue pushes inside him again, deeper this time, and the angle lets him reach further than before. His hands shift on Katsuki’s ass, spreading him wider, and Katsuki feels one thumb press against his rim, testing the resistance there.

The touch registers a second before the intent does, and Katsuki’s hand flies back on reflex.

The slap lands across the side of Izuku’s face with enough force that the sound cracks through the bathroom, sharp and unmistakable. Katsuki’s palm stings where it connected, and for one frozen second everything stops.

Izuku pulls back, his mouth leaving Katsuki’s cunt, and Katsuki twists to look over his shoulder. Izuku’s cheek is already starting to flush red where Katsuki hit him, his eyes wide with surprise, and his hand has dropped away from Katsuki’s ass entirely.

“Not here,” Katsuki bites out, his voice low and furious. “Not in Shouto’s fucking bathroom, are you insane?”

Izuku’s expression shifts, something like understanding settling into his features, and he lifts both hands in a gesture of surrender. “Okay,” he says quietly. “Okay, you’re right. Not here.”

The acknowledgment hangs in the air between them for a moment, Katsuki’s breathing still harsh and uneven, his body still trembling from the oversensitivity and the shock of having to physically stop Izuku from crossing that line. His hand is still raised, palm tingling, ready to slap him again if he needs to.

Izuku leans back in, slower this time, his eyes flicking up to check Katsuki’s face before his mouth returns to where it was. His tongue drags through Katsuki’s folds again, careful and attentive, his hands settling on Katsuki’s hips instead of his ass, the grip firm but not restrictive.

The tension bleeds out of Katsuki’s shoulders incrementally as Izuku settles back into the rhythm from before, his tongue working over Katsuki’s clit in those same slow patient circles. There’s something almost apologetic in the way Izuku’s touching him now, his movements gentler, more focused on drawing the pleasure out than pushing boundaries.

Katsuki’s forehead drops back to the door, his breathing starting to even out into something more controlled, and he feels Izuku’s tongue trace a path from his entrance up to his clit, the pressure steady and warm. The wet sounds have gotten quieter somehow, or maybe Katsuki’s just gotten used to them, his brain too overwhelmed to process the humiliation of it anymore.

Izuku’s mouth works over him with single-minded dedication, his tongue mapping every fold and crease, returning again and again to the spots that make Katsuki’s breath catch or his hips twitch. He seals his lips around Katsuki’s clit and sucks gently, just enough pressure to make Katsuki’s thighs shake harder, before releasing and using the flat of his tongue to stroke over the swollen bud in long slow passes.

The pleasure builds differently this time, less urgent and more inevitable, a slow steady climb that Katsuki can feel in the way his walls keep clenching rhythmically and the way his breathing has gone shallow despite his attempts to control it. His hand is still braced against the door, his knuckles white, and he can feel sweat trickling down his spine where his shirt has stuck to his skin.

Izuku makes another one of those satisfied sounds, his tongue dipping inside Katsuki’s entrance just enough to gather more slick before dragging it up and spreading it over his clit, and Katsuki realizes with a jolt that Izuku is still hard, still completely into this, still getting off on the act of eating him out even after being slapped.

“Izuku,” he tries again, his hand scrabbling back to push at Izuku’s head. “I came, you can stop now—”

Izuku’s grip on his ass tightens, holding him in place, and his tongue presses down harder.

The second orgasm builds faster than the first, his body still riding the aftershocks when the next wave starts to crest. His clit is too sensitive, the nerves screaming with every pass of Izuku’s tongue, but his walls are clenching again anyway, his body chasing the stimulation even as his brain tries to process whether this is pleasure or too much or some combination he doesn’t have words for.

“Stop,” he gasps out, his palm flat against the door now, fingers spread wide. “Izuku, seriously, someone’s gonna notice we’re both gone—”

Izuku pulls back just enough that Katsuki can feel the absence of his mouth, the cool air hitting wet skin and making him shiver. His hands stay on Katsuki’s hips, thumbs stroking idle circles against the bone.

“Grind on my face,” Izuku says, his voice low and rough.

The words land in Katsuki’s brain and refuse to make sense for a few seconds. His breathing is still harsh and uneven, his thighs still shaking, and he twists to look over his shoulder at Izuku with an expression that he knows must look completely wrecked.

“What?” The word comes out strangled.

“You heard me.” Izuku’s eyes are dark, his mouth and chin visibly wet in the bathroom light, and he’s looking at Katsuki like he’s got all the time in the world. “Grind on my face. Use my mouth.”

Heat floods Katsuki’s face so fast he feels dizzy with it, the embarrassment mixing with the arousal still thrumming through his nervous system. “That’s— no, I’m not—”

Izuku’s hands tighten on his hips and pull, forcing Katsuki’s ass back toward his face, and Katsuki has to brace harder against the door to keep from losing his balance. Izuku guides his movement, rocking Katsuki’s hips in a slow deliberate grind that drags his cunt over Izuku’s waiting mouth.

The sensation makes Katsuki’s breath catch, his whole body jerking at the contact, and he hears himself make a sound that’s halfway between a gasp and a whimper. Izuku does it again, using his grip to move Katsuki’s hips in the rhythm he wants, his tongue flat and still while Katsuki’s body slides over it.

“Stop,” Katsuki manages, his voice coming out thin and desperate. “I’ll— fuck— I’ll do it myself, just—”

Izuku’s hands loosen immediately, settling into a lighter hold that’s more guidance than control, and Katsuki feels the exact moment the responsibility shifts to him. His face is burning, his whole body flushed with humiliation and want, and he can’t believe he’s about to do this.

He rocks his hips back experimentally, the movement small and tentative, and feels Izuku’s tongue press up to meet him. The angle is different like this, the friction more direct, and Katsuki’s breathing stutters as he tries it again with more confidence.

Izuku makes an encouraging sound against him, and Katsuki’s hips start to move on their own, finding a rhythm that grinds his clit against the flat of Izuku’s tongue in rolling passes. His thighs are still shaking but for different reasons now, the muscles working to drive the motion, and he has to keep one hand braced on the door to maintain his balance while the other reaches back to grip the edge of the sink.

The wet sounds are obscene, his cunt sliding over Izuku’s mouth with each thrust of his hips, and Katsuki can hear his own breathing going ragged and desperate as the pressure builds again. It’s too much, it’s humiliating, it’s exactly what his body needs, and he can’t stop himself from chasing it.

Izuku’s hands guide him without controlling him, helping him maintain the angle when his legs start to give out, and his tongue stays flat and steady, letting Katsuki take what he needs at the pace he sets. The trust implicit in that makes something hot and complicated twist in Katsuki’s chest, but he doesn’t have the brain capacity to examine it right now.

His hips are moving faster now, the rhythm getting choppy and desperate as the third orgasm approaches, and he can feel his walls starting to flutter again, his body right on the edge of something that’s going to shatter him completely.

“Fuck,” he gasps out, his forehead pressed to the door, his hips grinding down harder. “Fuck, I’m— I’m gonna—”

Three sharp knocks hit the door at his back.

Katsuki’s entire body goes rigid, his breath stopping in his chest, his hips freezing mid-thrust. The orgasm is right there, his body balanced on the knife’s edge of it, and every muscle has locked up in panic.

“Hey, anyone in there?”

Kaminari’s voice filters through the wood, bright and casual, and Katsuki’s brain whites out completely for a second. He knows that voice, he’s known Kaminari since they were kids, and Kaminari is standing three inches away from him while Izuku’s mouth is pressed against his cunt.

“I—” Katsuki starts, but his voice cracks on the syllable and he has to clear his throat. His face is on fire, his whole body flushed with mortification, and he can feel Izuku’s breath against his inner thighs where Izuku has gone perfectly still. “Yeah, occupied.”

“Oh, shit, sorry dude!” Kaminari sounds embarrassed. “Thought it might be empty, the door’s been closed for like twenty minutes.”

Twenty minutes. Katsuki’s brain tries to process that information and fails completely. Has it really been that long? How has no one noticed they’re both missing? How has no one put it together?

“Just— give me a minute,” Katsuki manages, his voice strained.

“Yeah, yeah, no problem! Take your time!”

Footsteps retreat down the hallway, and Katsuki stays frozen against the door, his breathing harsh and shallow, his body still trembling with the orgasm that got interrupted. His hips are still positioned over Izuku’s face, his thighs still spread, and the humiliation of it crashes over him in a wave that makes his skin prickle.

He twists to look over his shoulder and finds Izuku watching him with an expression of pure satisfaction, his eyes bright with amusement, his mouth still wet. Izuku is clearly getting off on how flustered Katsuki is, how wrecked and panicked he looks, and the realization makes something hot and furious twist in Katsuki’s gut.

“You’re—” Katsuki starts, but before he can finish the sentence, Izuku leans forward and sinks his teeth into the soft flesh of Katsuki’s inner thigh.

The bite is sharp and sudden, not hard enough to truly hurt but enough to leave marks, and Katsuki’s breath punches out of him in a startled gasp. His hips jerk forward reflexively, pulling away from Izuku’s mouth, and his hand flies back to push at Izuku’s head.

“What the fuck,” he hisses, twisting further to glare at Izuku. “Someone just— Kaminari just—”

Izuku releases his thigh and presses a kiss to the bite mark, his lips soft against the stinging skin, and his eyes never leave Katsuki’s face. “He’s gone,” Izuku says quietly, his voice rough. “And you were so close.”

Katsuki stares at him, his chest heaving, his body still wound tight with the orgasm that got interrupted. His thigh is throbbing where Izuku bit him, and he can already feel the shape of the mark forming, the indentations of teeth pressed into his skin.

“Yo! Someone in there?”

Katsuki’s eyes go wide, his mouth falling open on a breath that won’t come, and the orgasm hits him anyway, rolling through his body in long shuddering waves that make his knees buckle. He has to bite down on his hand again to muffle the sound, his teeth sinking into the flesh between his thumb and forefinger, and tears stream down his face while his cunt pulses around Izuku’s tongue and Kaminari keeps talking on the other side of the door.

“Dude, I really gotta go! You gonna be much longer?”

Katsuki can’t answer, his throat locked up tight, his whole body shaking through the aftershocks while Izuku’s tongue finally, finally pulls away. He sags forward against the door, his forehead pressed to the wood and his shoulders heaving with each breath, and he can feel the wetness on his face and between his thighs and the way his legs are barely holding him upright.

Behind him, Izuku stands.

Katsuki hears the movement, the quiet creak as Izuku’s weight leaves the toilet seat, and then his presence is right there at Katsuki’s back, solid and warm and close enough that Katsuki can feel the heat radiating off him through his shirt.

“Yeah, sorry!” Izuku calls out, his voice completely steady and calm like he hasn’t just spent the last several minutes taking Katsuki apart with his mouth. “Just give me a minute!”

“Dude, you okay?” Kaminari asks through the door, concern creeping into his tone. “You sound kinda weird.”

Katsuki hears the zipper before he processes what the sound means, the quiet rasp of metal teeth separating, and his head turns slightly to look back over his shoulder. Izuku’s hands are working at his belt, fingers quick and efficient, and the realization of what’s about to happen hits Katsuki all at once.

“No,” he whispers, his voice coming out hoarse and wrecked. “Not now, he’s right there—”

“Might’ve had too much to drink,” Izuku says to Kaminari, one hand already pushing his pants down just far enough. “Might be a while actually, sorry about that.”

His other hand finds Katsuki’s hip and steadies him, thumb pressing into the bone there with firm pressure, and Katsuki feels something blunt and hot press against him from behind.

“Want me to get you some water or something?” Kaminari offers through the door. “Hold your hair?”

Izuku positions himself, one hand guiding his cock while the other keeps Katsuki steady, and Katsuki realizes with a jolt that the height difference is too much like this, that he can’t reach properly bent over the way he is.

“Nah, I’m good, thanks though,” Izuku says, his voice still perfectly calm, and then he’s bending down slightly to hook his hands under Katsuki’s arms and lift.

Katsuki’s feet leave the floor for a second before Izuku positions him, setting Katsuki’s feet down on top of his own shoes, the added height bringing them level. Katsuki has to grip Izuku’s forearms to stay balanced, his fingers digging into the muscle there, and he can feel Izuku lining himself up again, the head of his cock pressing against Katsuki’s entrance with steady insistent pressure.

“Izuku,” Katsuki manages, his voice barely above a whisper, tears still wet on his face. “Don’t—he’s right there, we can’t—”

Izuku pushes inside.

The stretch is immediate and overwhelming, his cock thicker than his tongue by far, and Katsuki’s oversensitized body tries to clench against the intrusion even as it opens for him. His hand flies up to cover his mouth, palm pressing hard against his lips to muffle the sound that wants to tear out of his throat, and his eyes squeeze shut as the first few inches slide in on the slick that’s gathered there.

The stretch burns, his rim straining around the width as Izuku pushes deeper, and Katsuki can feel every centimeter of the invasion, can feel his inner walls being forced apart to make room. His body is still swollen and sensitive from three orgasms, every nerve ending screaming at the intrusion, and the fullness is already bordering on too much when Izuku’s barely halfway in.

Katsuki’s fingers dig into his own cheek where his hand is clamped over his mouth, his teeth biting into the inside of his lip hard enough to taste copper, anything to keep from making a sound as Izuku keeps pushing deeper. His free hand scrabbles against the door, nails scraping uselessly against the paint, and he can feel fresh tears spilling down his face.

“How’s the party from in there?” Kaminari asks, still talking through the door. “You’re missing Shouto cutting the cake again. Momo made him pose for like thirty pictures.”

Izuku pulls Katsuki back onto his cock, slow and steady, feeding more of his length inside with patient thoroughness, and Katsuki has to press his forehead harder against the door to keep from making a sound. The stretch keeps building, his body struggling to accommodate the size, and he can feel himself shaking, his thighs trembling where they’re pressed against Izuku’s.

His rim is stretched so wide it aches, the muscle pulled taut around Izuku’s girth, and Katsuki can feel the way his walls are fluttering and clenching involuntarily, trying to adjust to the invasion. The pressure radiates through his pelvis, a deep burning fullness that makes his breath come in shallow gasps he has to force through his nose because his mouth is still covered by his palm.

“Tell him I’m sorry,” Izuku says, and his voice hitches just slightly on the last word as he pushes in deeper. “I’ll be out soon.”

Izuku pulls back just slightly, maybe an inch, and the drag against Katsuki’s walls makes him gasp against his palm. Then Izuku pushes forward again, deeper than before, the added depth making Katsuki’s body stretch further to accommodate. He repeats the motion, each shallow thrust working slightly deeper, the back-and-forth movement forcing Katsuki’s body to open incrementally.

The withdrawal tugs at his rim, the muscle pulled inward slightly with the retreat, and then the return thrust pushes it wide again, wider than before. Katsuki can feel his walls being coaxed apart with each small advance and retreat, his body learning to take more with every pass.

His body splits open around Izuku’s cock, and Katsuki can feel himself clenching rhythmically in response, his walls trying to adjust and accommodate and failing. His breath won’t come properly, each inhale catching high in his chest and stuttering back out. His knees are shaking so badly he’s barely standing, his weight held up mostly by Izuku’s grip and the way he’s braced against the door. Fresh tears spill down his cheeks, his vision blurring at the edges.

Katsuki can feel the vibration of Kaminari’s voice through the door where his hands are braced flat against the wood, each word traveling through the barrier and into his palms. His face is wet with tears and his cunt is stretched so full he can barely breathe and Kaminari is right there, separated from them by two inches of cheap wood and a flimsy lock.

“Bakugou’s missing too,” Kaminari says conversationally. “Kirishima’s looking for him. You seen him?”

Izuku bottoms out, his hips flush against Katsuki’s ass, and Katsuki’s breath leaves him in a rush against his palm that’s too loud in the small bathroom. The fullness is complete and overwhelming, Izuku buried so deep inside that Katsuki can feel him in his stomach, and his body is still trying to adjust to the intrusion, his walls fluttering and clenching around Izuku’s cock in rhythmic pulses he can’t control.

His hand is still clamped over his mouth, fingers digging into his cheek, and he can feel himself trembling, his whole body shaking with the effort of staying quiet while stretched this impossibly full. The burn of the stretch is radiating through his pelvis and down his thighs, and he has to lock his knees to keep from collapsing.

“Haven’t seen him,” Izuku says, and there’s something dark in his voice now, something satisfied. His hands tighten on Katsuki’s hips. “Maybe he went outside for air?”

The casual lie makes something hot and humiliated twist in Katsuki’s gut, fresh tears spilling down his face as he stands there stretched around Izuku’s cock while Izuku lies to Kaminari about where he is. His hand presses harder against his mouth, his palm wet now with spit and tears, and he can feel his breathing going ragged and desperate through his nose.

“Yeah, maybe,” Kaminari agrees. “Man, you sure you don’t want me to stay? You sound pretty rough.”

Izuku pulls out slowly, the drag of his cock against Katsuki’s oversensitized walls making fresh tears spill down Katsuki’s face, and Katsuki has to bite down on his own palm to keep from crying out at the sensation. The retreat is almost as intense as the entry, the stretch shifting but not lessening as Izuku withdraws, and then he pushes back in just as slow, the fullness returning all at once.

Katsuki’s body clenches around him involuntarily, his rim still stretched wide and aching, and he can feel the way his walls are gripping Izuku’s cock, can feel every ridge and vein as it slides back in. His hand stays clamped over his mouth, the only thing keeping the sounds trapped in his throat.

“I’m fine, really,” Izuku says, his voice steady even as his hips move in another slow deliberate thrust. “How’s the party? Everyone having fun?”

Katsuki can’t process that this is happening, that Izuku is having a completely normal conversation with Kaminari while fucking him against the bathroom door, that Kaminari is standing right there on the other side talking about cake and missing people while Katsuki’s bent over with Izuku’s cock buried inside him and tears streaming down his face.

“Yeah, it’s good!” Kaminari says, warming to the topic. “Sero tried to spike the punch but Iida caught him. Oh, and Mineta got kicked out for being creepy again.”

Izuku laughs, the sound warm and genuine, and the movement jostles Katsuki forward slightly, pushing him harder against the door. The impact makes Katsuki gasp against his palm, the sound escaping muffled, and he bites down on his own hand to keep anything else from coming out.

Izuku pulls out and thrusts back in, still slow but with more force this time, and Katsuki’s body jolts forward with the impact, his free hand slapping against the wood. The stretch intensifies with the thrust, his rim pulled even wider for a moment before Izuku’s hips settle flush against him again, and Katsuki has to close his eyes against the overwhelming fullness.

The door rattles in its frame.

“Yo, you good in there?” Kaminari asks, concern creeping back into his voice. “That sounded rough, man.”

“Yeah, just—” Izuku’s voice catches as he pulls out and drives back in, harder this time, and Katsuki’s hand presses so hard against his mouth he can feel his teeth cutting into his lip. “Stomach cramp. I really should’ve paced myself better.”

Katsuki’s trying to stay quiet, his jaw clenched so tight it aches and his hand pressed over his mouth, but he can feel the sounds building in his chest with each thrust, small desperate noises that want to escape. His cunt is clenching around Izuku’s cock in involuntary spasms, the stretch still intense and overwhelming, still too sensitive from three orgasms but responding anyway, and he can feel the wetness increasing, slick gathering and starting to drip down his thighs.

Each thrust makes the stretch shift, his rim pulled wider on the withdrawal and then forced to accommodate the full girth again on the return, and the constant cycle is making his legs shake harder, his body struggling to adjust to the rhythm.

“Alright, man,” Kaminari says finally. “There’s a bathroom upstairs if anyone else needs. Feel better, okay?”

“Thanks,” Izuku manages, pulling out slow and pushing back in deep, the fullness making Katsuki’s breath stutter against his palm. “Appreciate it.”

Footsteps retreat from the door, growing fainter, and then the sound of the bathroom proper’s door closing.

Kaminari’s gone.

The second Izuku registers the retreat of footsteps, everything changes. His hands tighten on Katsuki’s hips hard enough to bruise, fingers digging into the bone there, and he pulls out and slams back in with force that makes Katsuki’s whole body jolt forward against the door.

“Fuck,” Katsuki gasps out, his hand finally dropping from his mouth, no longer needing to stay quiet. “You’re fucking insane, we almost—he was right there—”

Izuku pulls out and drives back in harder, the impact making Katsuki’s palms slide slightly against the door where sweat has made them slippery, and the angle is perfect now, the head of his cock dragging against Katsuki’s front wall on every thrust in a way that makes stars burst behind his eyes. The stretch is relentless, his rim forced to accommodate the brutal rhythm, and Katsuki can feel himself being split open over and over with each thrust.

“But he didn’t know,” Izuku says, his voice rough now, the careful control finally slipping. He pulls out and thrusts back in, setting a rhythm that’s brutal and unrelenting, each impact driving deep enough that Katsuki feels it in his stomach. “Did he?”

Katsuki can’t answer, his voice breaking apart into gasps and choked sounds he can’t suppress, and his body is doing that thing again where it responds without permission, his hips pushing back to meet each thrust even as tears keep streaming down his face. The overstimulation is so intense it borders on painful, every nerve ending screaming, but the pleasure is building anyway, a fourth orgasm he doesn’t think his body can handle starting to wind tight in his pelvis.

The stretch is constant and overwhelming, his body forced to take the full length with each brutal thrust, and Katsuki can feel the way his walls are being dragged and pulled with every movement, the friction intense against oversensitized tissue.

“I can’t,” he manages between thrusts, his voice wrecked and desperate. “I can’t come again, Izuku I can’t—”

“Yes you can,” Izuku says, and his hand slides around to press against Katsuki’s lower stomach, adding pressure from the outside that makes everything more intense. “You’re going to.”

The rhythm is relentless, each thrust driving deep and pulling out just far enough before slamming back in, and Katsuki can hear the wet sounds getting louder, can feel his body making room for Izuku with each impact. His legs are shaking so badly he’s not sure how he’s still standing, his weight supported mostly by Izuku’s grip on his hips and his own hands braced against the door.

He can feel it building, the tension winding tighter despite how wrecked he already is, and his walls are clenching around Izuku’s cock in rhythmic pulses that make each thrust feel impossibly deeper. The stretch is so intense it makes his breath catch, his rim aching from being forced open over and over, and the pressure is building low in his pelvis, radiating outward into his hips and down his thighs.

“Izuku,” he gasps out, and he can hear how his voice sounds, broken and pleading. “I’m—you need to—”

He feels it then, the change in Izuku’s rhythm, the way his thrusts are getting less controlled and more desperate. Izuku’s breathing has gone ragged against Katsuki’s back, harsh gasps that ghost over Katsuki’s neck where his shirt has ridden up, and his grip on Katsuki’s hips is tight enough now that Katsuki knows there will be bruises tomorrow.

“Wait,” Katsuki manages, his brain finally catching up to what’s about to happen. “Izuku, wait—pull out—you have to pull out—”

Izuku’s rhythm doesn’t falter, his hips still driving forward in hard steady thrusts, and Katsuki feels panic starting to claw up his throat.

“Izuku,” he tries again, more urgent now. “Don’t—don’t you dare—”

Izuku’s grip tightens and he buries himself deep, hips flush against Katsuki’s ass, and Katsuki feels the first hot pulse flood into him, wet heat spreading deep inside where Izuku’s cock is pressed against his front wall.

“No,” Katsuki breathes out, and his voice cracks on the word. “You didn’t—”

Izuku’s cock pulses inside Katsuki in rhythmic contractions that Katsuki can feel against his oversensitized walls, and the warmth keeps spreading, more than Katsuki expected, filling him in a way that feels wrong and overwhelming and inescapable.

Katsuki turns his head to look back over his shoulder, twisting as much as he can in Izuku’s grip.

His face is still wet with tears, his eyes wide and shocked, and he stares at Izuku with an expression he can feel forming on his face before he can stop it—hurt and disbelief and complete betrayal all mixing together into something that makes his chest ache.

“You—” His voice breaks. “We talked about this—you can’t just—”

Izuku meets his eyes, still buried deep inside him, his chest heaving as he catches his breath. His face is flushed and his pupils are blown wide and he doesn’t look sorry, doesn’t look apologetic at all, just satisfied and dark and still hungry in a way that makes Katsuki’s stomach twist.

Fresh tears spill down Katsuki’s face, tracking over the ones already drying on his cheeks, and he can feel it inside him now, impossible to ignore—the warmth of Izuku’s cum spreading through him, the fullness of it, the way it sloshes slightly when Izuku finally, finally pulls out.

The withdrawal is slow and careful, Izuku’s cock sliding free with a wet sound that makes Katsuki’s face burn hotter, and then Katsuki can feel it starting to leak out, warm fluid dripping down his inner thighs to mix with the slick that’s already there.

“How am I supposed to—” Katsuki’s voice cracks again, and he has to stop and swallow hard before he can continue. “It’s inside, Izuku, how am I supposed to go back out there like this—”

He turns around fully, his back pressing against the door, and shoves at Izuku’s chest with both hands. “You fucking—we agreed, you said you wouldn’t—”

Izuku catches both his wrists before Katsuki can wind up for another shove, his grip firm but not painful, and pins them against the door on either side of Katsuki’s head. Katsuki tries to twist free but Izuku’s stronger, his body pressed close enough that Katsuki can feel the heat radiating off him, can smell his own slick and Izuku’s cum in the air between them.

“Let go of me,” Katsuki hisses, tears still streaming down his face. “You can’t just—”

“It’s not my fault,” Izuku says, his voice low and rough, and there’s something possessive in his eyes that makes Katsuki’s breath catch. “You were so cute tonight. So excited to see everyone coming together again. Smiling at everyone, laughing with Kirishima, hugging Mina—”

“So you—” Katsuki’s voice breaks on a sob. “So you thought you’d—”

“I needed to remind you,” Izuku continues, his grip tightening slightly on Katsuki’s wrists. “Who you belong to.”

The words land in Katsuki’s chest like a punch, and fresh tears spill over. He can feel it still dripping down his thighs, can feel the evidence of Izuku’s claim inside him, and his legs are shaking so badly now that if Izuku wasn’t holding him up he’d probably collapse.

“I hate you,” Katsuki manages, but his voice has gone thin and hollow.

Izuku leans in and brushes his lips against Katsuki’s temple, the gesture almost tender if it weren’t for everything that just happened, for the way Katsuki’s wrists are still pinned to the door.

“I know,” Izuku says quietly.

He releases Katsuki’s wrists and steps back, and Katsuki almost does collapse, his hands flying to the door behind him to keep himself upright. He can feel it shifting when he moves, warm and foreign and impossible to ignore, and the humiliation of it makes his face burn.

He reaches down with shaking hands to pull his underwear back up. The fabric catches on his thighs where they’re wet with cum and slick, and he has to peel it away from his skin to work it up over his hips. His jeans follow, the denim rough against his oversensitized skin, and he can feel Izuku’s cum soaking into the fabric of his underwear the moment he gets everything back in place.

“I have to go back to the party like this,” he says, his voice flat. “With your—with that—inside me.”

Izuku’s already tucking himself back into his pants, movements calm and efficient, and when he looks at Katsuki his expression is unreadable.

Three sharp knocks hit the door at Katsuki’s back.

His whole body jerks at the sound, his heart jumping into his throat, and he stares at Izuku with wide panicked eyes.

“Hey.” The voice through the door is familiar, calm and measured. “It’s me.”

Shouto.