Chapter Text
People thought that Deku was so sweet, so innocent, such a good person who could never do any wrong. Katsuki saw the way people flocked to him, falling all over themselves to get his attention, to help him, to just be in his gravity for a little while. The whole damn class was in love with him and, or so it seemed, and had been since first year. Precious omega Deku, one of three omegas in their alpha heavy class (the others being fucking Iida, of all people, and Yaoyorozu), so hard working and amazing.
A true hero in the making, everyone thought. Everyone but Katsuki who knew the truth: Midoriya Izuku was nothing but a slut and a tease, pretending to be innocent and wholesome.
He had everyone else fooled but not him, not when he walked around surrounded in a cloud of soft omega scent, a mix of spun sugar, fruit, and cream that had sat heavy of Katsuki's tongue since puberty had hit. Not when he was always touching people, further in their space than was polite, acting like some eager touch starved puppy. Not with the way he looked up at people like they were then only person in the world, lips parted in fascination or pleasure, eyes wide and sweet, fluttering his eyelashes and blushing at compliments like no one has ever been nice to him before. Not when he showed off his body, wearing his training clothes so tight, bending over and moving in ways that called attention to that sweet little ass, not when he was known for ending up with his clothes in tatters, putting muscle and that hint of omega curve and weight on display. Not when he didn't wearing a shirt under his button down half the time, allowing the world to see how his shirt clung to those barely there omega tits and big, dark nipples.
Everyone else might overlook all the signs Deku was throwing out but Katsuki picked them up loud and clear. He felt the truth in his gut, in his cock, in the throbbing of his knot when he jerked off and couldn't help but think of him. Deku was a slut, a filthy omega lapping up the attention of alphas, just begging with every little action for someone to shove a knot into his cunt or ass or mouth. He needed someone to touch him, to pull and bite at those nipples, to mark up his neck, scratch lines in that pale, scarred skin, to fuck the desperation right out of him.
Everytime time he stood at some alpha’s side, leaning into them, laughing and smiling as they put a hand on his arm, back, or neck, he was just begging to be used up. He needed someone alpha enough to hold him down and ruin him. Izuku needed an alpha who would leave him busted open, sloppy wet, dripping with their seed and gagging for their knot.
Katsuki was not that alpha. Oh, sure, he fucking thought about it often enough (everyone in their class was thinking about it) but he had things going on. Goals to aim for, training and work to be done, he didn’t have time for some omega or to let hormones or his knot tell him what to do. He had to keep his eyes forward, not to the side to pay attention to what his rivals and classmates were up to. Let Round-face, IcyHot, and all the rest drool over Deku but be too scared to make a move on him, let them all pant and watch and fall all over themselves for one stupid omega; he wasn’t going to get involved in it.
He did a damn good job of sticking that. Not even living together in the dorms and occasionally glimpsing the omega in a state of undress (boxers and t-shirts sometimes, little lacy bras and tiny cute panties other times) moved him. He was beyond it.
He had been beyond it, until the day Deku came back from a weekend at home dressed not in pants, but the skirted uniform. Katsuki knew just as well as anyone that all omegas were issues two versions of the uniform, one with pants and one with a skirt, allowing them to choose how they presented themselves. Most omegas did opt to be ‘female’, and if someone had asked Katsuki years ago if Izuku would be the same he would have said yes. When they’d been younger he’d come to school in frilly dresses, skirts, light colors, with ribbons or barretts in his riot of curls. Then in middle school he’d stopped, become strictly male presenting, and Katsuki had never cared enough to wonder.
Seeing him in a skirt was...bothersome.
He was blushing bright red, all the way up to his ears, eyes on the ground as he shuffled in. He was pulling at the hem of his skirt, short enough to brush against mid thigh and just a touch tight where it pulled over his ass, and chewing on his full lower lip. His tie was as out of sorts as it always was, and his blazer of a slimmer and higher cut than it normally was, nipping in at his smaller waist and making the flare of his hips look that much rounder and wider. His socks clung to his calves tightly, looking one good move away from splitting open completely around the well developed muscle. His thighs were hard, muscular, but also shapely, pale freckled skin littered with scars.
He was not the image of a beautiful, soft omega like Yaoyorozu was, didn’t fill out the uniform nearly as well, nor was he as frustratingly prim and proper as Iida, but there was something about him. There had always been something about Deku, much as Katsuki hated it. Something soft in it’s own way, delicate, pretty, in his own way, as much as he was rough around the edges. It made people love him and want to protect him at all costs, without fail.
It, whatever it was, was in full force today as he haltingly explained his usual uniform had a tear in it so he’d had to leave it with his mother and wear his alternate uniform for the day. Those who flocked around his desk, lead by Uraraka and Asui, made sympathetic noises, assured him he looked fine, were dragged into his orbit as they always were. Deku ate it up, of course, laughing and smiling as he was pet and jostled playfully, the alphas closest to him responding to the instinct to sooth and reassure an omega with touch and soft words.
Katsuki watched and seethed.
By lunchtime he was so pissed he could barely see straight. Izuku had spent the whole half of the day fluttering around, preening under the attention afforded to him. There were more touches, more looks in his direction and Katsuki knew he knew it. Why else would he constantly be nibbling and licking his bottom lip, drawing attention to it? Or constantly playing with his socks, hands smoothing over his calves and thighs as he pulled and straightened them time and again.
To say nothing of all the times Katsuki caught him bending over just enough, or stretching just high enough, to make the hem of his skirt lift and flash a hint of stark white panties, edged in yellow lace. Or the way his scent had thickened, turned sweeter with pleasure and happiness, and was creeping over the room, turning everyone else into happy, simpering idiots, oblivious to being caught in a low-level omega thrall.
Everyone except Katsuki, who was above that sort of thing. Totally completely above.
When he leaned forward over his desk to tell Deku to meet him during lunch to talk it was just so he could tell him to knock it off, and keep his gross scent to himself, not because he too was affected by it.
Which did beg the question of how exactly they ended up in some empty bathroom, Deku pushed up against the wall, thick legs wrapped around his waist while they kissed, wet and messy and hard. Their blazers were on the floor, pulled off and tossed aside as the distractions they were and Izuku’s tie was balled up at their feet. Katsuki had already pulled his shirt loose from his skirt, managed to pull away some of the buttons and push it down his shoulders, exposing pale white fabric, bits of lace, and a sweet little bow. Katsuki wanted to get his mouth all over his chest, to leave marks all over his skin, to mouth and bite and torture the small mounds until Izuku was in tears.
He drove his teeth into the omega’s full lower lip, sucked it into his mouth and pushed Izuku a little higher on the wall, pulled him tighter against his body. He tugged at the bra, pawed at it clumsily, until he’d managed to get it up and out of the way. He groped at the barely there swells, rubbed a thumb over one wide nipple to feel it stiffen and pebble under his touch. His stomach clenched, hunger spiking and growing in his gut
“Wait.” Izuku panted against his lips when Katsuki ground against him, rubbing their cocks together through their clothes. “Wait, Kacchan, wait, I can’t- your scent, I can’t think, it’s mmm-” He repeated when Katsuki’s hand slipped under his skirt to palm and squeeze his ass. “Wa-oh! Oh oh, don’t-”
The rest of what he was doing to say dissolved into a long drawn out moan when Katsuki sealed his lips over his scent gland and sucked. His tongue played over the raised bit of flesh, swirled and licked before he sucked again, harder, pressed his teeth into the edge. He held the omegas ass in his hands, commemorated the feel and shape of hard muscle and soft skin and flesh, a touch of curve, to memory.
“So...dizzy.” Deku gasped out, humping against him and pulling at his shirt. “Can’t. We can’t.”
Katsuki hooked his fingers into the flimsy fabric of the panties, ignored Izuku’s stuttered explanation of his boxers being too long to wear with the skirt, and then pulled them away with a flick of his wrist. The sound of them ripping filled the air, somehow louder than Deku’s panicked yelp. He tossed them aside carelessly, ignoring the sting of Deku’s nails digging into his biceps.
“Kaachan! I needed th-”
“Shut up.” He growled out, biting sharply at his neck. Not at the scent gland, even with his mind buzzing and his vision drenched red he knew not to do that, but down where it met shoulder, where it stretched into a graceful arc.
Izuku quaked against him, the punishing clench of his thighs becoming that much stronger. He reached to grab his ass with both hands again, spreading and kneading as he rocked against him. With the panties gone he could smell him, damp, heady, wanting, *begging* for it. Saliva filled his mouth and his gums itched around his alpha teeth; that smell was...god, he could taste it, thick and sweet and tempting. It called to him, pleaded with him to taste it.
“Is this what you wanted, flaunting your ass around all day, dressed like that?” He asked as his fingers sought out where Izuku was hot and damp with slick, thumbed at soft folds, dragged up until he felt the base of his cock. It was an awkward angle, his body weight and one hand keeping Izuku up against the wall, but he didn’t care. “Did you want some alpha to fuck you, Deku? No, I bet a slut like you wants to be passed around, bent over with your pussy stuffed full of cock by every alpha who smiles at you just right, until you’re full of their come. That’s it, right? Because that’s what happens to whore omegas like you.”
Izuku made a noise of protest but it was lost in another trembling moan when Katsuki’s thumb pressed into him. He had to press closer, curl his whole arm under the omega’s ass for leverage, and found his vision dripping red with lust and rage as velvety heat sucked his thumb inside. He moved it back and forth, rubbing against trembling walls, and slick gushed forth to cover his hand.
“K-kacchan.” Izuku gasped, head tilting back to thump against the wall. “We can’t, I-”
He bit him again, harder this time, and thrust his thumb harder into his quaking body. Izuku’s cock was pressing against the underside of his skirt, making it tent around him, and there was a dark spot spreading across the fabric. His scent was honey thick, dripping over everything, drowning Katsuki in it. Even as ‘don’t, wait, please’ fell from his lips his body held tight, drew him back in every time he pulled his thumb nearly free.
This was just what he’d always known Deku really was. Needy, shameless, playing at being anything other than a whore ready to spread his legs for anyone willing to take it.
Izuku squirmed, pushed against his hand with lusty mewls that got louder when Katsuki replaced his thumb with two fingers. His legs, crossed at the ankle and pressed tight to his back, shook. Katsuki looked up and saw his eyes were glassy, unfocused behind heavy lids, and his mouth was kiss swollen and parted, begging for more attention. Their mouths met again, wet and gasping. He pushed his fingers deeper into the omega, twisted them roughly as he fucked into his cunt and his tongue slid past his lips.
Katsuki wanted to see his cock between them, sliding between those plush pink lips, pushing into his throat and making him choke on it. He wanted to finish all over that pretty face, to see him drooling and splattered with his come, ruined by him.
But mostly he wanted to fuck him, now. He slipped his fingers out to fumble with his belt and pants, leaving Izuku to stay up on his own for a moment. The omega was breathing hard, clawing at his arms and shoulders, muttering nonsense about needing to think clearly and pheromones and alpha highs; his usual bullshit. Katsuki listened with half an ear as he fished his cock out, slick and purpling at the head, knot half inflated. He stroked it, spread Deku’s slick and his own precum from tip to just above the knot.
Deku hiccuped, pupils stretching so wide his eyes were nearly black, chanted that stupid nickname as his fingers curled and gripped him tighter. Katsuki pushed him up higher on the wall, hiked up his skirt, and guided his cock to his cunt. He rubbed the tip against Izuku’s slit, felt it parting to welcome him in. A thrust up and he was in past the head and Izuku let out a strangled moan as hips stuttered forward then pushed down, taking him in further. He was tight and fluttering around him, soft and soaking, clinging to his cock. He pulled the omega down further as he thrust up into him to sink in to his knot. Another thrust and that too was in Izuku, stretching his cunt wide to fit it. It was only a hand over Izuku’s mouth that kept his wail muffled as Katsuki rocked up into his body, forcing his knot deeper, making him take his cock all the way to the hilt.
The drag back was slow, merciless, and a wave of slick followed, dribbling down over his knot when it popped back. He fucked back into him greedily, pistoning in and out with rapid strokes; the position limited him to short jerky thrusts, dragging out about halfway before pressing in until his knot was teasing at Izuku’s cunt, stopping short of fully entering again. The omega’s hips moved against him, making him bounce on his cock; lewd, wet squelching filled the small bathroom, mixed with their mingled grunts and moans. Katsuki’s knot swelled and filled, the skin itching in the best way as it stretched. He bent at the knees, moved his arm more beneath Izuku to hitch his legs up a bit higher, and slammed into the tight, willing passage
Izuku wedged a hand between them, under his skirt, to grip his cock and Katsuki found himself grinning savagely. “That’s right Deku, touch yourself. Come on my dick, show me how much you wanted this.”
Deku came with a keening cry, eyes rolling back in his head and body shaking. Katsuki pounded into him, pulling more gasps and hiccuped pleas to stop ‘it’s too much, too much’ until he was forcing his knot back inside and spilling into the trembling omega. Izuku cried out again, body locking down around him to hold him inside.
---
Neither of them got to eat and they were both late for class. Katsuki strolled in first, having left Izuku a mess back in the bathroom. He’d been slumped against the wall, hair sweaty and matted to his head, shirt rumpled and more off than on, bra hiked up, and skirt a wet, sopping mess. His cunt had been gaping, come and slick trickling out of his body to spread over his thighs in thin rivulets.
Katsuki barely stepped into the classroom when all eyes turned towards him. He could see on their faces that they knew right away. Deku’s scent was heavy on him, mingled with sex and omega arousal and he hadn’t done more than a quick clean up. His cock was sticky in his pants and his knot was only just deflated enough to have allowed him to zip up. His mouth was still tingling from the force of their kisses.
He wanted to shout his victory at them, to confirm with words what they all knew already. He’d fucked their precious Deku, made him a filthy mess in a handy bathroom, knotted him then left him full of his seed and dripping his scent like the easy slut he was. He’d do it again, if he wanted, and he knew Deku would let him. Might even beg him to do it.
“Bakugou,” Aizawa drawled without turning around from the chalkboard. “Go into the hallway and wait there.”
He was still there, leaning against the wall with his hands in his pants pockets, when Izuku finally came hurrying down the hallway, still looking a fucked out mess and reeking of Katsuki. The collar of his shirt covered that marks he’d bitten into his skin and Deku had had found some skin tight shorts to pull on, Katsuki could see the bottoms of them peeking out from beneath his skirt, but he was walking funny and nursing a split lip. His tie was even more crooked than usual and his blazer was buttoned just as crooked. Katsuki smirked at him, laughing quietly when the omega flushed bright red up to the roots of his hair.
Izuku fumbled the door open, stepped inside and- “Hallway, Midoriya.”
“Yes sir.” Deku mumbled, stepping back out and sliding the door back into place. He fumbled with his tie and blazer while they waited, a stricken look on his face.
Katsuki watched, another smirk pulling at his lips. They were in trouble, a lot of it probably, but it was worth it to have shown everyone the truth about Deku.