The den was dark, the single lamp painting everything in deep amber and longer shadows. Izuku stood just inside the doorway, his back against the cool wood, watching Katsuki pour two fingers of whiskey into a tumbler. The silence between them was a live wire, humming with the memory of the basement, of the dryer’s metallic shudder against his spine. Katsuki didn’t offer him a drink. He just took a slow sip, his crimson eyes fixed on Izuku over the rim, a silent question. Why are you here?

Before Izuku could fabricate an answer, a sound cut through the muffled quiet of the house. A low, punched-out moan. Then another, higher, breathy. It was coming from the other side of the den’s large, floor-to-ceiling bookcase, from the direction of the rarely-used sun porch.

Katsuki’s eyes sharpened. He set the glass down without a sound. A jerk of his head commanded Izuku to follow as he moved, a predator’s glide, to peer through the gap between the bookcase and the wall.

Izuku’s breath hitched. On the sun porch, bathed in the cold blue light of the moon through the windows, were Hitoshi and Denki. Hitoshi was braced over Denki, his indigo hair falling into his face, his hips driving forward in a relentless, smooth rhythm. Denki was arched beneath him, one hand fisted in Hitoshi’s shirt, the other clamped over his own mouth. The wet, rhythmic slap of skin on skin was obscenely loud in the sleeping house.

“Fuck, ‘Toshi,” Denki gasped, his voice a broken whisper, his legs tightening around Hitoshi’s waist.

“Quieter,” Hitoshi grunted, but there was no real reprimand in it, just a rough, tired affection. He dipped his head, sucking a dark mark onto Denki’s throat, his own pace never faltering.

Izuku couldn’t look away. His own body reacted before his mind could muster shame. A hot, slick ache pulsed between his legs, his small, sensitive nipples tightening painfully against his sweater. He felt Katsuki’s heat at his back, not touching, just there. He could hear the faint, ragged pull of Katsuki’s breath beside his ear.

“Look at that,” Katsuki murmured, his voice a gravelly vibration against Izuku’s temple. “Cousin’s got his boy split open on his cock. You hear that? How wet he is for him.”

Izuku whimpered, a tiny, traitorous sound. On the porch, Hitoshi shifted his angle, and Denki cried out, the hand on his mouth falling away to claw at the sheets on the bed beneath them. The scent of sex—musk and sweat and salt—began to seep into the den.

Katsuki’s hand came up, not to touch Izuku, but to grip the bookshelf beside his head, his knuckles white. Izuku could see the thick line of his uncle’s arousal straining against his jeans. “That’s what you sound like,” Katsuki breathed, the words hot and damning. “When I’m fucking into that greedy little cunt. You sound just like that.”

Denki was babbling now, happy, incoherent praises. “Right there, yes, yes, ‘Toshi, please, I’m gonna—”

Hitoshi choked off Denki’s words with a searing kiss, his thrusts turning erratic, brutal. The final sounds were a raw, shared groan and the slick, frantic pulse of their climax.

Izuku watched, transfixed, as Denki’s back arched off the sheets, a sharp, keening cry tearing from his throat as he came. A visible gush of clear fluid soaked the sheets beneath him, the moonlit proof of his climax shimmering on the fabric. Hitoshi’s pace never broke, his own hips stuttering as he buried himself deep, a low groan rumbling from his chest as he followed Denki over the edge.

Katsuki’s body pressed flush against Izuku’s back, a solid, unyielding line of heat. Izuku felt the thick, hard ridge of his uncle’s cock grind deliberately against the seam of his jeans, right over the curve of his ass. “See that?” Katsuki’s whisper was a raw scrape in the dark, his lips brushing the shell of Izuku’s ear. “The little slut soaks everything. Just like you do for me.”

On the porch, Hitoshi was collapsing onto Denki, their breathing ragged in the sudden quiet. Katsuki’s hands came to Izuku’s hips, fingers digging in, holding him in place as he kept up that slow, torturous grind. The friction against his own aching clit, trapped in his jeans, made Izuku’s knees buckle. Katsuki held him upright.

“He’s still got his boyfriend’s cock in him,” Katsuki murmured, his voice thick with a hunger that stripped away every pretense. “Feeling him pulse. Feeling him fill that tight little cunt up. That’s what you want, isn’t it, nerd? To be fucked so full you can’t think straight.”

Izuku couldn’t speak. He could only watch as Hitoshi finally, slowly, pulled out of Denki. The sight of his cousin’s thick, glistening cock, the way Denki’s pussy glistened, wet and used in the moonlight, sent a fresh wave of slick heat flooding Izuku’s own underwear. He whimpered.

“Shh.” Katsuki’s hand slid from his hip around to the front of his jeans, palming the soaked fabric there. Izuku jerked, a full-body shiver wracking him. “Already dripping for me. Just from watching. You’re such a little slut.”

On the sun porch, Hitoshi, still buried deep inside Denki’s glistening cunt, began to move again. It wasn't the slow, rebuilding rhythm from before. It was a hard, fast, punishing drive of his hips, the wet slap of skin echoing violently in the quiet. Denki’s head thrown back, a sharp, broken scream tearing from his throat before he could smother it.

“Fuck, listen to that,” Katsuki growled into Izuku’s ear, his other hand coming up to fist in the back of Izuku’s sweater. “Your cousin’s fucking wrecking his boy’s tight little hole. Making him scream. You wanna scream like that for me, nerd?”

Izuku could only shake his head, a weak, denying motion, even as his hips pushed back against Katsuki’s hard cock. “N-no…”

“Liar.” Katsuki’s fingers hooked into the waistband of Izuku’s jeans and underwear, yanking them down to his thighs in one brutal motion. The cold den air hit Izuku’s exposed, dripping cunt, making him gasp. Katsuki’s warm, calloused palm replaced it, cupping him entirely, his middle finger sliding through the slick folds with a filthy, wet sound. “Soaked. Fucking river. All from watching.”

He pressed that finger inside, just to the first knuckle, and Izuku’s knees gave out. Katsuki held him up, his own body a cage, as he worked his finger in and out, a shallow, mocking mimicry of the fucking happening yards away. “This what you need? Huh? You need to be split open on a cock, just like your cousin’s doing to his piece of ass?”

“Kacchan, please—”

“Please what?” Katsuki’s voice was dark, amused. He withdrew his finger, bringing it to his lips and sucking it clean with a low, deliberate groan. “Tastes like sin. My sin.”

The sound of Hitoshi’s relentless pace was a metronome. Denki was sobbing now, a stream of “yes, yes, yes,” each word punched out by a thrust. Katsuki’s hands went to his own jeans, the rasp of his zipper obscenely loud. He freed his thick, heavy cock, the flushed head already beading with pre-cum. He pushed the weeping slit against Izuku’s soaked opening, not entering, just grinding the hot, silken skin there against Izuku’s throbbing clit.

Izuku cried out, a shattered sound. Katsuki clamped a hand over his mouth, the taste of salt and whiskey on his skin. “Quiet. You wanna get us caught? You wanna let them see what a greedy little nephew I’ve got? How he leaks for his uncle’s cock?”

He rubbed himself against Izuku, the broad head catching on his entrance with every pass, a promise of stretch, of ruin. Izuku was trembling violently, his own hands gripping the bookshelf, his vision blurring as he watched Hitoshi piston into Denki, their bodies a single, driving shadow in the moonlight.

“He’s gonna fill him up again,” Katsuki murmured, his breath hot against Izuku’s neck. “Gonna pump his cum so deep into that pretty trans boy cunt it’ll leak out for hours. That what you’re thinking about? You wanna be full of me, Izuku? You wanna walk around tomorrow with my cum dripping down your thighs while you smile at your fucking boyfriend?”

“Stop,” Izuku begged, the word muffled by Katsuki’s hand, his body arching back to get more of that maddening friction.

“No.” Katsuki shifted his hips, the head of his cock notched firmly at Izuku’s entrance. He applied a slow, inexorable pressure. Izuku felt himself begin to give, the incredible, burning stretch starting as the thick crown pushed past his clenched muscles. “You don’t get to tell me to stop. You came here. You stood there and got wet watching. This is what you wanted.”

He sank another inch, and Izuku saw white, a choked scream trapped behind Katsuki’s palm. On the porch, Hitoshi’s rhythm fractured, his own groans joining Denki’s wails as they peaked together again, a messy, violent crescendo. Katsuki buried himself to the hilt inside Izuku at the exact same moment, a brutal, claiming drive that stole the air from Izuku’s lungs.

“There,” Katsuki panted, his voice raw with triumph. “Now you’re full. Just like him. Feel it?”

He didn’t move. He just held himself there, impossibly deep, letting Izuku feel the sheer, overwhelming girth of him, the way his body strained to accommodate it. Izuku could only nod, tears leaking from the corners of his eyes, his own cunt fluttering wildly around the invasion. He was split open, pinned, owned. And he had never wanted anything more.

Katsuki began to move. It wasn’t a tentative stroke or a testing rhythm. It was a harsh, driving piston of his hips, slamming into Izuku’s soaked cunt with a force that knocked a choked sob from his throat. The wet, fleshy sound of their joining was a brutal counterpoint to the frantic slaps from the sun porch.

“That’s it,” Katsuki growled, his voice strained with the effort of his thrusts. “Take it. You wanted a show, you got one. Now you’re the fucking show.”

On the porch, Hitoshi was grunting, a low, animal sound. “Cum for me again, Denks. Do it.”

“I can’t— it’s too much—” Denki whined, his voice frayed and wet with tears.

“You can. You will.” Katsuki’s words were a hot, mocking echo against Izuku’s skin, his pace never faltering. He fucked into Izuku with a deep, grinding finality on every inward stroke, making Izuku’s toes curl against the floor. “Hear that? Your cousin’s making his boy break. Just like I’m gonna break you.”

Izuku’s vision swam. The stretch was immense, a burning, perfect fullness that stole his breath. Each withdrawal was a loss, each brutal return a shock of pleasure so sharp it bordered on pain. He could feel the slick gush of his own arousal coating his thighs, feel the hot drip of it where their bodies met. “Kacchan—”

“What?” Katsuki snapped, his hand still clamped over Izuku’s mouth, his hips a relentless machine. “You gonna beg? Beg for your uncle to fuck you harder while your boyfriend sleeps upstairs?”

Denki’s cries pitched higher, a desperate, keening wail. “Toshi, I’m— I’m gonna squirt again!”

“Yeah,” Hitoshi rasped, his own control shattering. “Do it. Soak me.”

The sound that followed was a gushing, watery release, distinct and obscene in the quiet night. It seemed to trigger something in Katsuki. He snarled, a raw, unfiltered sound, and doubled his pace, his balls slapping against Izuku’s ass. “There. You hear that? That’s you. That’s what you do for me. Now do it. Squirt on my cock, you little slut. Do it right now.”

The command, the overwhelming pressure, the shameless, wanton sounds from the other room—it collided inside Izuku. A coil of pure, white-hot tension in his belly snapped. His back arched violently against Katsuki’s chest, a silent scream behind the hand as his cunt convulsed, clamping down in a rapid, fluttering rhythm. A hot, gushing flood burst from him, soaking Katsuki’s cock and thighs, pattering onto the floorboards beneath them in a shameful, audible stream.

Katsuki groaned, a deep, satisfied sound that vibrated through Izuku’s entire body. “Fuck. Yes. Just like that. Ruin my fucking cock.” His thrusts became erratic, brutal jabs, chasing his own end. On the porch, Hitoshi’s rhythm dissolved into a series of final, deep lunges, a low groan tearing from him as he finished.

Buried to the hilt, Katsuki stiffened. Izuku felt the hot, sudden pulse deep inside him, a claiming flood that made his spent cunt twitch. Katsuki held himself there, grinding faintly as he emptied himself, his breath a ragged pant against Izuku’s neck. For a long moment, there was no sound but their harsh breathing and the faint, satisfied murmurs from the sun porch.

Slowly, Katsuki’s hand fell from Izuku’s mouth. He didn’t pull out. He stayed lodged inside, a heavy, spent weight. His lips brushed Izuku’s ear, his voice a wrecked, quiet rasp. “Look at them.”

Izuku, trembling and hollow, forced his eyes open. On the porch, Hitoshi had collapsed half-on, half-off Denki, both of them still and gleaming with sweat in the moonlight. They were a tangled, sated mess. A mirror.

“That’s us,” Katsuki whispered, the words a grim, undeniable truth. “Two filthy secrets in the dark.” He finally withdrew, the sudden emptiness a cold shock. A thick trickle of his release immediately slid down Izuku’s inner thigh. “Clean yourself up. You’ve got a fiancé to go back to.”