Work Text:
Thud, thud, thud.
Moving into the apartment next to Deku had seemed like such a good idea. It meant they could leave for work together in the mornings, could share strategies and plan patrol routes for the day ahead.
Thud.
It meant they could slouch in front of some old All Might documentary together on Deku’s lumpy couch when they got home.
Thud.
And it meant that Katsuki was in close enough proximity that he could keep his best friend alive when Deku inevitably ran out of instant ramen noodles on a weekly basis. Katsuki’s home-cooked meals were only ever a knock on the door away.
It was practical, it was efficient.
Thud… thud.
It was the worst fucking decision Katsuki had ever made.
He groaned and pummelled his heels into the bedspread in disgust, twisting the measly little foam earplugs more tightly into his ears. It was time to invest in some of those noise cancelling headphones, no matter the expense.
Because every month, every single fucking month that Deku went into heat, Katsuki had to listen to the sound of him being ceremoniously fucked through the thin wall that separated their bedrooms. It was driving him insane.
It would at least be better if Deku had even a modicum of fucking taste, but if the stench of sub-par alpha that lingered in their shared hallway the next morning was anything to go by, the shitty little omega was happy to take anything he could get. He probably used one of those heat/rut dating apps to find the first willing alpha available to pound him into his mattress (and his fucking headboard, apparently).
It was insulting that Deku would stoop so low, degrading himself like some needy omega slut. Didn’t he know he could do better? Didn’t he stop to think for a second about the goddamn top-tier alpha cock in the very next room?
Thud – “Ah, ah, oh fuck!” – thud.
Katsuki growled long and deep, curling his hand into a fist and smacking it against his forehead in frustration. It was three in the fucking morning. And those obscene noises coming from Deku’s dirty mouth made him horny as fuck.
He couldn’t take it anymore. His traitorous dick was hard as a rock, and he’d barely slept a wink in the last three days.
Throwing the bedclothes away with a rumble, Katsuki scrambled to his feet, his front door banging on its hinges as he launched himself down the corridor. He slammed his fist against Deku’s door, pounding at it ferociously for several long minutes.
They probably thought he’d give up and go away at some point. Haah! As if he’d ever given up on anything. He’d bang on the door all damn night if he had to.
Eventually, the stomping of heavy feet sounded from inside the apartment, and Katsuki readied himself for the confrontation.
“Dude, what the fu –“
The moment the door swung open, Katsuki socked the big, ugly alpha right in his big, ugly nose.
“Fuck!”
Blood spurted merrily down the man’s face, dripping down onto Deku’s dusty, neglected floor. Katsuki’s eyes widened at the tangy, iron scent, lips curling back over bared teeth.
“There’s more where that came from,” he snarled. “Unless you want to fuck the hell off.”
“What the –“
“Kacchan?”
The familiar, sunshine voice sounded drowsy, deeper and throatier than Katsuki was used to. Deku’s head bobbed out from behind his bedroom door, curls askew and eyelashes heavy. He frowned when he saw the state of his floorboards.
“Kacchan? What are you doing here?”
Deku had wrapped himself up in a bedsheet to peep around the doorframe, and Katsuki’s dick throbbed heavily against his thigh at the sight of him. He looked like a whole fucking meal.
“I’m here to give you one last chance, you unbearable idiot,” Katsuki gritted out through clenched teeth. “Either I pack up my shit tomorrow and move way across town where I can scrub the mental image of this loser bending you over backwards out of my mind –“
The ugly alpha’s mouth opened in protest, but quickly shut again when Katsuki dropped a swift knee to his balls.
“- Or you can kick him to the curb and invite me the fuck in, for once.”
Deku’s face blanched for a second, but quickly recovered, flushed as he was with the rosy glow of heat. He glanced from Katsuki, to the alpha in the entryway, and back again, eyes wide.
“Well?” Katsuki grunted, tapping his foot theatrically. “What’s it gonna be, fuckface?”
Deku swallowed thickly, his eyelids drooping low as he fixed Katsuki with those drunken, green eyes.
“In,” he said. “Get the hell in here.”
Katsuki smirked, utterly vindicated as he grabbed the other alpha by the shoulders and flung him out into the corridor, clad in boxers alone.
“Hey, you can’t just –“
“Goodbye.”
Katsuki didn’t even throw a glance back over his shoulder as he slammed the door closed. He stalked toward Deku, who had let the sheet slither to the ground, revealing his taut, stocky body – and his aggressively hard dick, which bounced up wet against his stomach.
Katsuki shucked his shirt up over his head and pounced.
Deku was on him before he could even make it through the bedroom door, jumping up to grip steely legs around Katsuki’s waist in delight.
“Kacchan,” he sighed, breathless against Katsuki’s mouth. “I never – I just never thought you’d want –“
Katsuki shut him up with a kiss that tore them both into tiny little pieces, tongue delving into Deku’s hot mouth like he needed it to survive another day.
Lush, springtime grass and the sidewalk after rainfall – that was Deku’s scent – and Katsuki groaned at the feel of slippery, delicious slick wetting his midriff between Deku’s thighs.
He stumbled to the bed, flopping them both heavily onto the sheets. Strong fingers rose up to meet him, rolling and pushing Katsuki down until he was splayed out on his back, prone. Katsuki’s nose huffed at the scent-drenched air, inhaling lungfuls of it as Deku straddled him with a look more sinful than any Katsuki’d ever seen.
“Need you,” Deku murmured, raising himself on his knees and reaching around for Katsuki’s cock. “Need you now.”
When Deku sunk down, splitting himself over Katsuki’s dick like it came as second nature to him, Katsuki could swear he saw stars behind his eyes. And when Deku started to move, Katsuki was fucking sure of it.
“Holy shit.”
Deku bobbed relentlessly up and down, muscular thighs straining with the effort, his sloppy hole clenching around Katsuki, warm and velvety soft. Katsuki snaked his hands up Deku’s torso to rub his thumbs over the little, pink nubs of his nipples, surging up to take one in his mouth when Deku groaned in response.
“Oh, Kacchan, oh fuck –“
Each breathless moan shot straight to Katsuki’s cock, his hips jolting up – deeper, deeper – until Deku ground down into him, nails scrabbling feebly at his chest.
“Fuck me, Kacchan – fuck me, alpha.”
Katsuki had never seen Deku so pliant. So willing and so fucking obedient in response to Katsuki’s touch.
“Who you gonna call when you’re in heat from now on, huh?” Katsuki growled, grasping Deku’s hips bruisingly hard, slapping him down onto his lap again and again.
Deku’s eyes were closed, squeezed tight as his hands raked Katsuki’s shoulders, his arms – clawed his nails across every inch of Katsuki’s skin that he could reach.
“Who?” Katsuki repeated, hips canting up, menacingly deep.
“Y-You, Kacchan! Only you!”
Katsuki delighted in seeing his hero partner so utterly wrecked on the end of his cock.
“Who’s your fuckin’ alpha, Deku? Say it.”
Deku’s eyes sprung open, lips parting as Katsuki wrapped his fist around Deku’s dick and tightened his grip.
“Y-You!” Deku gasped. The wet, slapping sound as he fucked himself back onto Katsuki was practically immoral. “You, Kacchan, you’re my alpha.”
And with that admission, Katsuki came – hips snapping up hard, pumping at Deku’s dick until he spurted over Katsuki’s tensed abs in return.
“Don’t say a fucking word,” Katsuki muttered in the aftermath, their chests heaving from the frantic first-time fuck. “We’re gonna do that again.”
He lifted his best friend up and off him, sweat-slicked bodies sliding across each other as Katsuki flipped Deku onto his stomach and laid his substantial weight across the omega's scarred back.
“We’re gonna do that again, for as many times as it takes for you to remember that next time you go into heat – it’s me that’s gonna be the first to know.”