Katsuki was wide awake before he was consciously aware of why. There was no obvious disturbance, no sound or unexpected sensations that could explain the way he jolted abruptly from sleep. The air was quiet and still, with no indication that he was anywhere other than the bed he’d slept in for the past two years and change. But he’d never had cause to doubt his instincts — always sharp, now honed by years of training and bitter experience.
Something had to be wrong.
He was lying on his side, left arm curled up to pillow his head in the crook of his elbow. Assuming he was still in his dorm room, he would be facing the wall — if anyone else was there, they almost certainly couldn’t see his face.
It was worth the risk. Without moving another muscle, he cautiously cracked one eye open.
With his vision still fogged by sleep and not adjusted to the darkness, he could barely make out anything. The shapes in front of him were hazy and indistinct, but enough to prove two things. One, he was definitely still in his dorm room — or at least a damn good replica. And two, there was a faint light cast on the ceiling from where the door was ajar.
Instantly he was poised, his heart thumping in his chest loud enough to shake his skull, his body coursing with icy energy. His mind was racing, thoughts churning and colliding in his head. If villains had breached Heights Alliance, the whole class could be in danger. Should he yell? Set off his quirk as a warning? On the other hand, it was entirely possible that he was the only target — hell, it wouldn’t be the first time.
As he lay still, frantically turning over his options, the slice of light on his ceiling silently narrowed and disappeared as the door swung shut. The click of the latch was almost deafening in the quiet.
Immediately Katsuki screwed his eyes shut, cursing himself out in his head. Stupid! He’d hesitated, and now he was shut in his room with an intruder whose identity and intentions were a complete unknown. He could still get away if he had to — even if the glass of the balcony door was reinforced, there was no way it would withstand an AP Shot. But his options were severely limited now, and there was no way of getting a warning out without immediately inviting retaliation and sacrificing his element of surprise.
There were a few soft footsteps as the intruder moved further into the room. Whoever this asshole was, they certainly weren’t in a hurry. Katsuki clenched both his hands into fists and flexed his fingers, pumping blood and energy into his palms, silently warming up his quirk. What the eternal fucking hell did this bastard fucking want?
The voice was soft. Hesitant. A little reedy and a little wobbly, small in the charged air and yet so fucking unmistakable that it hit him right in the gut. His body’s cocktail of reactions was so powerful that it sent him reeling — shock, confusion, and a strange, sickening relief all seeming to bleed together.
But could he be relieved, yet? Was this really Deku, and not some disguise or voice-altering quirk? Given the situation, that seemed more likely than not — some villain scoping him out, borrowing the nerd’s likeness to test his consciousness, see if he would respond to that old familiar voice.
And even if it was Deku… then what?
The footsteps shuffled closer, coming to a stop right beside the bed. Katsuki was sweating. His stomach was churning painfully, teeth clenching hard, but he kept his breathing as steady as he could. Until he knew what was going on, he couldn’t make his move.
“Kacchan, are you awake?”
The voice was slightly louder now, a low murmur just a few feet away. The words, the tone, the lilting uncertainty — it all sounded like Deku, so much so that Katsuki felt aggravation rise in his chest, inexorable as the tides. He allowed himself a quiet grunt, venting just a little of the potent emotion into the room, but still didn’t move.
There was a long silence. For a time, the intruder just stood there, motionless.
And then the mattress creaked.
What the fuck! Katsuki’s mind screamed to itself as Deku — or a Deku-shaped imposter — lifted the covers and slipped quietly into the bed. He was solid beside Katsuki’s back, his weight making the mattress dip so that Katsuki’s body shifted closer to him, just barely brushing against his chest. Katsuki could smell him — just the faintest hint of unfamiliar detergent on his soft, well-worn t-shirt.
“Mmm,” Deku-not-Deku sighed, settling his head onto the pillow next to Katsuki, “it’s warm.”
An arm — sinewy, less bulky than Katsuki’s own yet still strong — snaked over and wrapped loosely around Katsuki’s waist. Through his tank top, Katsuki could feel the outline of Deku’s arm brace, and oh fuck. This really had to be Deku. Deku’s arm, Deku’s voice, Deku sneaking into Katsuki’s room at ass o’clock at night to — what? Get in bed with him? Cuddle him? Fucking spoon him?
Katsuki clenched his fist until the knuckles nearly popped, quickly calculating whether he could target Deku’s face precisely enough at close range to avoid blowing his own head off. But just then, Deku’s hand shifted, and every thought fell out of Katsuki’s brain.
Deku wasn’t even touching him much. Just a soft press of his palm flat against Katsuki’s abdomen, fingers splayed out and thumb rubbing slow circles through his tank. It was barely anything — and yet Katsuki felt his breath hitch and his skin break out in goosebumps, all the way up his chest and down his arms. He’d never thought of his stomach as being particularly sensitive, but it undeniably was, the nerves lighting up under Deku’s stroking fingers. Even through a layer of cotton, it was enough that Katsuki had to work to suppress a shiver.
“Kacchan’s so strong,” Deku whispered to himself, his breath puffing hot and damp on the side of Katsuki’s neck.
Slowly, that hand worked its way up and along the planes of Katsuki’s stomach. It meandered often, fingertips making detours to dip into hollows and lovingly trace the outline of his abs. Every touch drew Katsuki’s attention to a new part of his body — a new place for Deku to worship, to draw out delicate, tingly sensations from Katsuki’s skin.
It was creepy. It was weird. It was gross.
It felt so damn good.
Getting bolder — probably encouraged by the fact that Katsuki still wasn’t stirring — Deku slid his hand further up to cup one side of Katsuki’s chest. “Oh wow,” he breathed, squeezing and releasing. “I thought they’d be hard, but it’s so pillowy.”
Katsuki gritted his teeth, turning his face further into the pillow. It still felt good, those broad fingertips massaging his chest, kneading gently into the muscle. But pillowy?
Even without looking, he could sense an overwhelming energy radiating from Deku — the simmering tension in his body, the edge of something raw and manic in his voice. His excitement was palpable, crackling through the close space between them and causing the fine hairs on Katsuki’s arms to lift. It had to be the first time Deku had done something like this — there was no way Katsuki could have slept through a previous attempt. What the fuck was the idiot’s goal here?
Deku nuzzled his nose into the back of Katsuki’s neck, still groping with his big stupid hand and muttering away with his big stupid mouth. “Kacchan trains his chest to support his quirk, so of course it makes sense that he’s bulky here, but still…” He shifted, moving his hand up to grip boldly onto Katsuki’s pec through his tank top. In the process, his rough palm brushed over Katsuki’s nipple.
Katsuki jolted, a shock going through him from his chest all the way down his body, and — no. No, no, no, no, fuck no.
He was not about to get hard from the damn nerd touching his damn chest, there was no way in hell, it was simply not happening. But then Deku let go just long enough to take Katsuki’s nipple between his fingers and pinch — and oh, god, fuck. A bolt of pleasure, hot and shockingly intense, shot straight down Katsuki’s spine to his cock, and it was all he could do to keep from moaning aloud. As it was, his body jerked in Deku’s hold, his toes curling into the sheets under him.
They both froze, Katsuki fighting to control his breathing, Deku’s hand unmoving on him. It was a welcome chance for him to gather himself, willing his heart to stop its wild hammering against his ribs that surely Deku would be able to feel. But even as he fought to calm down, he couldn’t help but want that hand — trembling but otherwise motionless — to keep touching him.
“Kacchan?” Deku whispered into the darkness.
Katsuki felt his stomach drop through the mattress and down into the floor. Deku had to be onto him. Maybe it was always obvious that his sleep was fake — that he’d been lying there awake the whole time, allowing everything to happen. How could he ever face Deku again, if the nerd knew that Katsuki would let him get away with this shit? That Katsuki was fucking weak to being touched?
Keeping his eyes firmly closed, he forced himself to relax, resettling on the pillow with a low sigh. His heart was still pounding restlessly, the line between nerves and anticipation blurred to the point it had eroded almost entirely. There was no way — no way in hell — that he could let Deku realise he was awake.
Eventually, Deku’s hand began to move again, crawling delicately back down Katsuki’s torso. Each touch was cautious, fingertips selecting their landing spots with careful deliberation as they picked their way over his skin. Deku seemed to be testing the waters, probably spooked by his close call. But even so, the muttering didn’t stop.
“Sensitive,” he said giddily, tracing circles with one fingertip around Katsuki’s navel, making him fight to keep from squirming. “I bet Kacchan likes having his nipples played with. He must love having them sucked…”
With a sudden huff, he wriggled even closer, pushing his knee up to press it in between Katsuki’s legs. The movement caused them to shift, Deku’s hand slipping lower as Katsuki’s hips were nudged forwards, and suddenly Katsuki’s potent desire was colliding with his worst nightmare as Deku’s knuckles brushed against his half-hard cock. It was a fleeting touch, connecting with the barest amount of pressure through his boxers, but it was more than enough for Deku to notice.
“Oh,” Deku said in wonder. Katsuki could practically see the dumb sparkle dancing in his eyes.
Painfully slowly, Deku turned his hand over. One fingertip at a time, it settled over Katsuki’s crotch with the lightest of touches. The heat coming off his palm was incredible, even through the barrier of fabric between them. But all the touch achieved was to ignite Katsuki’s nerves still further, the contact just enough to draw his attention to his building arousal without any stimulation to scratch the itch.
Katsuki couldn’t hold back. He humped, just once, into Deku’s hand.
“Wow,” Deku said, his fingers tightening just a little. “Kacchan’s having fun.”
And then Deku was fully palming his cock through his underwear: rubbing along the underside, thumbing over the head, sliding down to grip around the shaft as much as he could. It was sweet torture, the soft cotton dragging across his sensitive skin, friction and pleasure in equal measure. Katsuki hissed through his teeth, feeling his hips twitch in place under Deku’s relentless touch.
“Maybe he’s having a sex dream?” Deku murmured, rocking his palm back and forth. “He’s getting so hard — so hot — mmm, feels big, Kacchan…”
And fuck, but hearing Deku praise him, his voice soft and sincere and reverent, only made Katsuki hotter. He had no idea how he would feel about this in the morning — couldn’t imagine how he would react to seeing Deku’s sweet, childlike face around the dorms or in class. But his growing need had a mind of its own, and no such reservations. Curling his toes to anchor himself in the sheets, he made another shallow bucking motion into Deku’s touch.
Deku’s gasp sounded positively delighted. He paused his ministrations, just long enough that Katsuki’s hips shifted forwards of their own accord to chase them down again.
And then, with a pleased hum, he snaked his hand under Katsuki’s waistband.
Deku’s skin was hot, so rough that it should have been uncomfortable, but the delicate way he wrapped his fingers around Katsuki’s dick meant the friction stayed on the right side of pleasurable. For a moment Deku just lay there with his hand down Katsuki’s pants, unmoving except for a subtle sporadic twitching of his fingers where they gripped loosely around Katsuki’s shaft. Katsuki could feel his cock throb in time with his rapid heartbeat, pulsing into Deku’s palm.
“Oh my god,” Deku whispered. He pulled his arms in tight, tugging their bodies closer together.
It was obvious when they came into contact just how much Deku was enjoying this. The outline of his hard cock jutted against Katsuki’s ass, demanding attention. It felt solid, firm and unyielding through the layers of clothing between them. Katsuki was gripped by a sudden, mad urge to grind back against it.
He could feel the bands of scar tissue across Deku’s hand, smooth then coarse then smooth again, as it began to stroke. It set a steady pace, pumping slowly and deliberately along the length of Katsuki’s cock, squeezing gently every now and then. Once his rhythm was established, Deku added a twist of the wrist on the upstroke, sweeping a slow, delicious drag from base to tip before moving to tease one fingertip in soft circles just below the crown. It felt amazing — Katsuki had to bite the inside of his cheek to contain his groans.
Deku must have had a lot of practice jerking off. That fucking loser.
The pad of Deku’s thumb rubbed over the head of Katsuki’s cock, sloppily collecting a fat bead of precum. “Wow, Kacchan likes this so much. He’s getting so wet… I wish I could see it…”
Out of nowhere, Deku unravelled himself from around Katsuki’s body, leaving him reeling and far too untouched. There was a soft sucking noise close to his ear, followed by a moan — was fucking Deku tasting his fucking pre? — but before he could think too much about it another hand was hooking in his waistband and tugging.
Katsuki had to suppress the instinct to pitch in: lift his hips so that Deku could get his underwear off quicker and get back to touching him already. It was painful having to sit through Deku’s fumbled, half-assed attempt at undressing him. Luckily, Deku seemed to feel the same way: as soon as he got the waistband down to the tops of Katsuki’s thighs he abandoned his efforts, reaching back around to palm lazily at the slick head of Katsuki’s dick. The feeling was heightened after being left untouched for a while — the heat of Deku’s hand, the sensation simultaneously delicate and overwhelming on the hyper-sensitive tip of his cock.
Katsuki managed to keep his breathing steady, but couldn’t disguise the way his legs twitched when Deku’s other hand slipped in between them from behind. It traced along the junction of his thighs, inching up slowly, gently, dragging blunt fingertips over sensitive skin — before pressing suddenly, deliberately upwards.
Katsuki hissed despite himself, his legs clamping down involuntarily. Deku’s thick fingers were pushing steadily against him, applying firm pressure to the spot right behind his balls. Katsuki had never touched himself there — it wasn’t even on his radar as a place he might want to try touching. But the pleasure was startling: different from stroking his cock but no less intense, a bone-deep, full-body feeling that made him want to hump back into the sensation. He gritted his teeth against it, his eyelids threatening to flutter. Why the fuck was he feeling so good from Deku touching his damn taint, of all things?
Suddenly, a hot puff of breath in Katsuki’s ear dragged his attention in yet another direction. Deku was plastered to him again, every limb clinging tight, breathing loud enough to wake the dead.
“Kacchan is so perfect,” Deku panted, nuzzling his nose into Katsuki’s hair. “So hot… hah, smells so good…” A hot kiss landed on the back of Katsuki’s neck, punctuated by a wet drag of tongue.
Everything was escalating so much further than he could ever have predicted. But it all felt so good — one hand pumping his cock, another pressing so deliciously into that sweet spot between his legs, even that tongue licking hungrily along his neck. The hand between his legs was shifting slowly, going from steady pressure to a slight rocking motion, inching ever so slowly further back with each stroke. It was unlike anything he’d ever felt before, and he couldn’t find the will to want it to stop.
When Deku abruptly took his hands away of his own accord, it took all Katsuki’s strength not to yell in frustration. But rather than disengaging, Deku crowded closer, nudging Katsuki with his body while one hand pushed insistently at his hip. With Katsuki keeping his body limp and slack in feigned sleep, it was easy for Deku to roll him over until he lay flat on his front. The position pinned his cock between his abdomen and the mattress, and pressed the side of his face into the pillow so that one eye and half of his mouth were smothered. His heart was slamming against his chest, feeling almost giddy with embarrassment and anticipation.
Deku was quiet for once, save for the shuffling of sheets and shifting of the mattress as he repositioned. Katsuki could feel him wriggle down the bed, dragging the covers back with him as he went, until he was kneeling up over Katsuki’s prone body and straddling one of his legs. Those hot, rough hands resettled on his skin, this time splaying out to encompass his upper thighs. The fingertips tightened briefly, pressing into the muscles of his legs. And then two strong thumbs dug into the creases of his ass and tugged, spreading his cheeks apart.
Before Katsuki had a chance to process, something slick and warm slid along his crack. The sensation was alien and unexpected, completely unlike anything he’d felt before. It was slippery, too soft and yielding to be a finger, almost like…
Deku’s quiet moan confirmed Katsuki’s suspicions. The sound vibrated directly against him along with a puff of breath, right before another wet slide over his skin — and there was no question about it any more. Deku was licking his asshole.
Katsuki’s immediate instinct was to clamp his legs together — maybe, if he got enough leverage, he could pop Deku’s head like a grape. But those damn hands were still on him, holding his thighs down with a grip of steel, and that tongue made a circling motion around his hole that left him boneless. It felt gross — a slimy, wriggling intrusion into a place where a tongue had no right to be. But even so, it awakened all his nerve endings, drawing his attention for the first time to just how sensitive that part of his body was. He could feel every single darting motion of Deku’s mouth, every lap of tongue and tickle of breath. It was like Katsuki was being peeled open, the loving licks and soft moans seeping into his body and turning his bones molten.
“Kacchan tastes so good,” Deku slurred.
His mouth was messy and uncoordinated, lips dragging and tongue flicking back and forth along the delicate skin. Katsuki suppressed a shudder. A part of him still couldn’t believe that Deku would so readily put his mouth on another person’s ass — but god help him, it hit him in the gut with a powerful shot of arousal all the same. His face was on fire, breath laboured, his cock throbbing where it was pinned against the mattress — and all he could want was more. Without meaning to, he spread his legs wider, arching his back to tilt his ass up into Deku’s face.
Immediately, he froze. Dread curdled in his stomach: terrified that after all his efforts, he’d given himself away just like that. But Deku welcomed the new position greedily, fingers squeezing into Katsuki’s thighs to hold them apart as he buried his face closer in between. Whether he thought Katsuki was the world's heaviest sleeper or wasn’t thinking at all was unclear. But Katsuki couldn’t dwell on it for long, distracted by that strong tongue pressing forward and dipping in—
He couldn’t react in time to keep the sound in. He was lucky that the pillow against his face muffled most of it — and that at that moment Deku seemed wholly focused on burying his entire face in Katsuki’s ass. Even then his sounds didn’t stop, pouring from his lips and directly into Katsuki’s body, groans and gasps interspersed with slurred half-syllables of ka and ahn. Deku’s tongue was hot, surprisingly firm as it speared inside him, licking him open with slow, persistent strokes. And then — fuck — it started to thrust, pushing in and out like Deku was fucking him with his mouth, the rhythmic pulses sensual yet nowhere near enough to be satisfying. Katsuki clenched his fists where they were hidden safely under the pillow, holding motionless save for the motions of Deku’s tongue rocking his oversensitive cock into the mattress under him. It was almost impossible to suppress the urge to lift his hips for more.
Deku gasped sloppily when he finally came up for air, leaving a mess of spit in his wake. “Hah — god, he’s so — wanna touch him—”
As if the little freak hadn’t already touched him more than anyone else ever had — but Deku was crawling up over him, the fabric of his shorts rustling. For his height, the nerd was surprisingly heavy, his bodyweight compact and solid as he shifted to straddle both of Katsuki’s thighs. And then, loud in the still room, there was the plasticky snap of a bottle.
Holy shit, Katsuki thought as a slippery finger slid down the crack of his ass. Deku came prepared.
There was no pain when the finger pushed in. It entered slow but smooth, all the way to the knuckle in one motion, the slide eased by spit and the lube that Deku had brought. Katsuki’s toes curled against the sheets — it felt so wrong, a foreign invasion inside him, cold and slimy on his heated, shuddering flesh.
Somewhere close by, Deku gasped. He sounded ridiculous.
The finger retreated partway, only to push gently back in at a different angle. Thankfully, Deku was going slow — probably scared of waking him. The lube was already warming up, and the new angle was just a little more comfortable, conforming slightly better to the shape of Katsuki’s body. With a deep, slow breath, he forced himself to relax, overriding the instinct of his muscles to tighten around the alien presence.
“God, Kacchan…” Deku groaned, his other hand landing on the meat of Katsuki’s ass to squeeze lovingly. “He’s taking me so well — he’s enjoying this, right…?”
Cautiously, Deku started pumping his finger, and sure enough Katsuki felt his body respond to being fucked, even if just by a single digit. He couldn’t spread his legs any further — his underwear was still around his thighs, keeping them trapped no more than a few inches apart. But his hips were tilting back into Deku’s hand, his toes were curling, and his cock was still hard and leaking onto the sheets. Suddenly, he wasn’t sure if he wanted Deku to keep being gentle.
“Kacchan’s so perfect,” Deku huffed, pulling his hand back and touching another slick finger to his rim.
Slowly, so slowly, the second finger breached. That did hurt a little: the intrusion stretching him in a completely unfamiliar way, Deku’s thick fingers jostling together inside of him. But something about the burn felt good — satisfying — an ache that promised pleasure beyond, if he could just be patient. He turned his face slightly further into the pillow, muffling his mouth, forcing back the moan that threatened to escape as both digits seated themselves knuckle-deep in his ass.
“Oh wow,” Deku whispered, his other hand reverently massaging Katsuki’s hip. “He’s tight, but… it’s like he wants more…”
He curled his fingers together, slowly, and Katsuki’s eyes rolled back in his head. God fucking damn it, but Deku was right. Those fingers were rubbing over sensitive places Katsuki never knew were there, lighting up his nerves every time they moved, and the stretch when they pressed in to the hilt was addictive. Deku didn’t seem to be aiming for any spot in particular, just lazily exploring the inside of Katsuki’s ass with his fingers as he muttered away. At some point his other hand had let go of Katsuki’s hip. Katsuki could vividly picture the nerd tugging at his own lower lip, deep in thought, taking furious mental notes on the fingerfuck as he went.
Katsuki’s heartbeat rang loudly in his head when a third finger teased at him, his body tensing instinctively and threatening to clamp down — but Deku stroked gently at him, cooing sweet nonsense with that lilting voice. He massaged Katsuki’s rim with soft, soothing motions, working the wetness around with a sloppy fingertip, occasionally dipping in next to the first two fingers to push more lube inside. Soon, Katsuki had relaxed enough for the third finger to sink all the way in right along with the rest.
Deku was breathing heavily, his weight shifting on Katsuki’s thighs. There was another rustle of fabric and a hiss of breath, and then a slick, rhythmic noise of skin on skin started up. Deku let out a soft moan, his body curling a little further forwards. Inside of Katsuki, his fingers twisted before gently, insistently, splaying apart. Katsuki felt so fucking full, the stretch of it overwhelming as he fought to hold still and not give himself away. His legs were shaking, but he couldn’t control it: his only option was to pray that Deku wouldn’t notice it from under the blankets.
Those soft sounds were speeding up, Deku’s legs giving little desperate twitches on either side of Katsuki’s thighs as he humped forwards sporadically. “Hah — ahh — oh my god, Kacchan, is it okay? It doesn’t hurt, right? C-can I?”
The sound when Deku pulled his hand back and out was obscene. It left Katsuki gritting his teeth, feeling exposed and cold and empty, his cock aching and pulsing weakly where it was trapped against his abdomen. Perversely, he envied Deku’s freedom to jerk himself off.
“Can I, just a little?” Deku babbled, inching his hips further forward, his weight bearing down on Katsuki’s legs. “He must feel incredible… Kacchan, please—”
And the broad head of Deku’s cock nudged against the cleft of his ass. Katsuki could feel soft, hot skin, the wetness of pre smearing across his slick, twitching hole, fucked open by Deku’s crooked fingers.
He went deliberately slack, but his mind was screaming — not at himself, but at that fucking idiot thinking with his stupid dick. He wasn’t even wearing a condom, for fuck’s sake! Was he really so reckless to come equipped with lube but no condoms? Granted, Katsuki was fairly sure Deku was healthy — and he knew for certain that he was clean himself — but Deku had no way to know that.
That train of thought was cut off swiftly when the teasing at his asshole grew more purposeful. Deku was rocking back and forth now, shifting forwards just enough to apply some pressure — just enough to encounter resistance as Katsuki’s body pushed back on its own against his dick.
“Yeah, just a little… Just the tip is okay, right? Oh my god, Kacchan…”
The next time Deku rocked forwards, he didn’t shift away. He was holding still, pressing the spongy head of his cock gentle and steady against Katsuki’s hole. Katsuki could hear loud, pained breathing above him, long heavy puffs as Deku seemed to gather his nerve. Then, finally, he moved.
He went deliberately slow, pushing smooth and steady on Katsuki’s rim until, sure enough, it softened. The entirety of Katsuki’s attention was concentrated and focused on the moment his body gave way — the moment the very tip of that thick cock dipped into the space it was creating. A powerful shudder travelled through him, reeling at the heady sensation of being filled — of Deku’s dick pushing inside of him—
There was a loud rush of breath behind him, a giddy exhale almost bordering on a laugh, and one of Deku’s hands dropped heavily onto the bed. “Hhhhot…!”
Deku gave the slightest twitch of his hips, easing himself just barely further forwards until he had squeezed the whole head of his cock through that initial ring of muscle to sit solid and throbbing inside. Even after all the fingering, Katsuki didn’t feel prepared for the stretch, the way his ass opened up to take it like it was inevitable. He was losing his mind, could hardly stand to hold himself still. His body screamed to pull away — to rock back onto it — the warring instincts overlapping and blending together until they hardly felt contradictory anymore.
“Feels good,” Deku gasped, his hips shaking in place. “Even better than I thought…”
He pulled out for a moment, just long enough that Katsuki’s hole began to close around nothing, and then repeated the motion — opening him back up with the head of his dick until it slipped past the rim again. Katsuki could feel Deku’s rough knuckles brush against the sensitive skin of his ass as he guided his cock with his hand; could feel the rhythm of Deku’s pulse throbbing erratically inside of him.
“Oh my god,” Deku panted. He released his shaft and dropped his other hand to the mattress, both arms bracing on either side of Katsuki’s back. “So good, Kacchan — Kacchan—!”
With that, finally, Deku started to move. His fingers curled into the sheets, supporting his weight on his arms as he rocked his hips tentatively, easing his cockhead slowly in and out. He was obviously trying to hold back — maybe even thought he was succeeding — but every stroke went just a little harder, seating himself just a little deeper, spearing Katsuki open just a little more. Deku was fucking him in incremental steps, slick cock pulsing slightly further in each time before easing back, soft grunts and moans pouring from his mouth with each twitch of his hips.
Katsuki shuddered, eyelids fluttering, mouth slack and gasping into the pillow under his face. Even just the tip had been overwhelming — by now he felt tender and raw, worked open for Deku to fill him. With each press forwards, the head of Deku’s cock nudged against a spot inside him that sent pleasure coiling through his body, a slow ember that threatened to light and spread. And the nerd just kept going deeper, feeding more and more dick into his ass with every press of his hips. It was driving him insane: the slide and drag along his walls, the simmering pressure inside of him that crested and waned in time with the teasing rhythm. He could sense the unspent energy in Deku’s thighs where they bracketed him, shaking with effort as Deku struggled to hold back.
“A-amazing…” Deku’s voice was husky and strained, fraying at the edges. “I knew he would be, but… it’s like Kacchan was made for me…”
Finally, on the next instroke, Deku couldn’t hold back any longer. His cock kept pushing, far past the halfway point and all the way to the base. Carving out new space for itself in Katsuki’s guts — and punching a hoarse gasp out of his throat.
Instantly, his pleasure curdled into icy nausea in the pit of his stomach. His body was coiled and thrumming, fighting the almost overwhelming urge to go rigid — but if he gave in, Deku would feel it.
But Deku wasn’t moving. His hips were still flush with Katsuki’s ass, breath puffing hot and steady onto the back of his neck. His arms were solid where they bracketed Katsuki’s back, the full weight of his body bearing down. Katsuki felt so full, stuffed to the brim with cock, stretched so wide that he could feel Deku’s pulse throbbing inside of him.
“Kacchan feels good too,” Deku murmured. He gave a grind of his hips, his cock rubbing firm against that sweet spot and making Katsuki’s mouth drop open on a helpless moan — and oh fuck, oh shit, Katsuki was so fucking screwed. “I’m making Kacchan feel good,” Deku whispered gleefully, pumping his hips to rock his stupid thick dick in place. “He's taking me so perfect, so hot and tight, and he likes it too, oh fuck, god, Kacchan…”
Finally, Deku started to fuck him properly, pulling out excruciatingly slow before sinking all the way back in. As he seated himself deep again, he actually whined, the sound coming out choked and high-pitched in between his loud panting breaths. He sounded like a dog. It should have been disgusting. But his cock was rubbing deliciously against Katsuki’s walls, making his legs quake and his pulse beat hard in his head. Every inward stroke rocked Katsuki’s dick down into the mattress, where it was pinned between his belly and the bed, and all he wanted in the whole world was to reach down with his hand and relieve the painful pressure building in his gut. But he was trapped — completely helpless to Deku’s whims — and fuck, the nerd was going so slow that Katsuki wanted to scream.
Deku was running his mouth a mile a minute, seemingly convinced by this point that nothing short of a bomb going off would make Katsuki wake up. “He’s breathing so hard… What’s he dreaming about? Ah, I wish I’d done this sooner, it’s so good — I wanted this for so long, Kacchan…”
Just like before, Deku’s control was gradually slipping the more time passed. His pace had quickened, now thrusting deep and steady, each time pressing firm into Katsuki’s hot spot. The pleasure was agonising: steady strokes inside of him, stretching him open, pressure on his cock as Deku’s thrusts carried through him and forced him to hump against the bed in turn. Katsuki felt like he’d been hard for hours, the slow build of his arousal so drawn-out that by that point he could think of nothing else but getting off. Far too late, he registered that the pillow under his face was damp. He must have been drooling into it, his mouth hanging slack and useless — but as soon as he tried to close it, Deku fucked into him again and sent his mouth dropping open on another suppressed moan.
He couldn’t resist. As discreetly as he possibly could, Katsuki began to move in time with Deku’s pace: rocking down into the bed each time Deku pushed in and subtly rutting his leaking dick against the mattress to steal stimulation. The sheets under his belly were wet, sticky with pre and excess lube, and the rub of slick cotton against his throbbing crown was borderline painful. But it was so good, so needed, exactly what his tortured body was craving. Deku’s cock was hitting him perfectly every time, and on the next stroke he pushed in deep and just stayed, grinding firm and slow against that tender, aching spot inside. It sent sweet, sticky pleasure licking through Katsuki’s core, up his spine, down his legs — and suddenly, the reality of the situation hit him hard.
He was going to come. Deku was fucking him in the ass as he pretended to sleep and he was going to come — and he wanted it; craved it; couldn’t even summon the will to avoid it.
Moving cautiously, he tilted his body as much as he dared, pressing his ass back into the cradle of Deku’s hips to encourage his cock deeper. Deku choked, his fingers curling tight into the sheets on either side of Katsuki’s face as if straining to control himself — but he took the bait anyway. The sound of their skin slapping was audible when he started moving again, fucking into Katsuki in bold, smooth strokes, pin-point targeting his hot spot with the fat head of his cock. Katsuki tensed and shook, biting hard into the pillow under his face as at last, finally, he tipped over the edge.
His orgasm ravaged him. It was nothing like what he was used to from jerking off: harder and stronger and more profound, making his thighs shake and his ears ring. His cock, trapped against the bed and almost completely untouched, was pulsing and twitching violently against his belly, drenching the sheets under him with scalding cum.
“Oh my god,” Deku groaned in his ear. “Kacchan, Kacchan, fuck—”
Abruptly, Deku pulled out. For a split second, Katsuki felt disturbingly, achingly empty — until his attention was grabbed by the sudden, shocking sensation of hot fluid spattering across his skin. Deku was gasping, his legs tensing and gripping around Katsuki’s thighs as he humped forwards, coming messily all over Katsuki’s ass and lower back. When he was finally spent, he sagged forwards, his body going loose and slack.
For a moment, all Katsuki could register was the heaving of breath. He couldn’t tell which of them it belonged to.
Eventually, Deku released a shaking sigh and sat back. One of his hands trailed over the mess he’d left, his thumb circling absently to rub his cum into Katsuki’s skin. “I wish I could see,” he sighed wistfully to himself. “This must look so pretty.”
Crawling back, Deku leaned down one more time. This time his tongue was lazy, dragging slowly and methodically across Katsuki’s skin to lick everything up. Even so, Katsuki had to work to suppress a shudder: his skin was buzzing, so sensitive that he could feel every little movement of Deku’s mouth, every light brush of his hair against his lower back. He was wet and sticky, lying in a slowly cooling puddle — and still reeling in the wake of the most powerful orgasm of his life. Even Deku’s little laps of tongue felt good, tracing mindless, soothing patterns on his hot, flushed skin.
Once Katsuki was licked mostly clean, Deku sat up with a wet, satisfied sigh. “That was incredible,” he murmured. One of his hands lifted, and Katsuki’s ears just barely caught the soft sound as Deku wiped off his mouth on the back of his wrist. “I’m glad Kacchan felt good too.”
Deku moved quietly and carefully as he shifted up to stand. With one rough finger, he stroked a stray lock of hair back from Katsuki’s ear before leaning down and pressing a chaste kiss to the side of Katsuki’s jaw. His breath was warm and damp, smelling of mint and musk and, faintly, of cum. Katsuki suppressed a shudder, keeping his breathing as slow and steady as he could.
“Sleep well, Kacchan,” Deku whispered. Turning, he padded softly away towards the door, his bare feet almost soundless. “Sorry to disturb you.”
And with that, he slipped from the room and eased the door quietly closed behind him.
Katsuki was left, heart pounding hard to pump cold horror through his chest, eyes wide open and unseeing in the dark of his silent bedroom.