Toshinori’s sobs quieted into a low, possessive rumble against Izuku’s spine. His softening cock was still sheathed in his son’s ruined ass, a claim that felt more permanent than Katsuki’s seed in his pussy. When he lifted his head, his eyes weren't shattered anymore—they were dark, focused, and fixed on Katsuki. "You made me do this," he breathed, his arms tightening around Izuku. "But he’s still my son."

Katsuki didn’t move from where he leaned against the arm of the couch, his own cock still glistening and hard. He watched Toshinori’s transformation with a cold, approving smirk. "Prove it," he said, his voice a graveled command.

Toshinori’s hands slid under Izuku’s thighs, his grip bruising-tight. With a grunt of effort that was all raw need, he lifted Izuku clean off the floor, holding him suspended in the air. Izuku cried out, a sharp, broken sound, as his father’s cock, already hardening again, dragged brutally inside him. Toshinori began to fuck up into him, hard, precise pistons of his hips, Izuku’s legs splayed wide open by his father’s unyielding hands.

"Kacchan," Izuku whimpered, his head lolling back, his body a pliant, speared weight in the air.

"Look at me," Katsuki ordered, stepping forward. He gripped Izuku’s jaw, forcing his glazed eyes to focus. "You’re not done. You’re never done." He positioned himself, the broad, slick head of his cock nudging against Izuku’s soaked, swollen pussy. "This is still mine."

He pushed in. A choked scream tore from Izuku’s throat as he was filled completely, stretched to a blinding, impossible fullness from both ends. The sensation was less like being fucked and more like being split apart, remade. Toshinori’s thrusts drove him onto Katsuki’s length, and Katsuki’s drives pushed him back onto his father’s.

"See-saw, you little slut," Katsuki growled, setting a brutal, synchronized rhythm with Toshinori. Their bodies slapped against Izuku’s, a wet, obscene percussion. "Take it. Both of us. Every inch."

Izuku’s mind dissolved into pure sensation. "I’m—I’m a hole," he babbled, the words slurred and dripping. "Just a fuckhole. Your fuckhole. Dad’s fuckhole. A c-cock sleeve."

"Louder," Toshinori grunted, his breath hot against Izuku’s neck, his thrusts becoming ragged, desperate.

"I’m a dumb, cock-drunk bitch!" Izuku screamed, the confession tearing out of him as the dual penetration hit a spot so deep it whites out his vision. "Made for this! Only for this! Please, please, don’t stop—"

Katsuki watched the boy shatter, his own control a tight, fraying wire. He leaned in, his lips against Izuku’s ear, his thrusts never faltering. "Who do you belong to, Izuku?"

Izuku’s answer was a sobbing, shuddering wail. "You! Kacchan! I belong to Kacchan!"

Toshinori’s rhythm hitched, a possessive snarl in his throat, but he didn’t stop. He fucked into his son’s body with a fervor that was an answer in itself—a claim, a damnation, and a surrender all at once.

The rhythm broke into something competitive and punishing. Toshinori’s thrusts became erratic, deep lunges that lifted Izuku higher with each snap of his hips. Katsuki matched him, driving up into the tight, slick heat of Izuku’s pussy with a brutal, measured force that shoved the boy back down onto his father’s cock.

“That’s it, you greedy little thing,” Katsuki snarled, his hands digging into Izuku’s hips. “Take your father’s dick. Show him how well I trained this cunt to milk a cock.”

Izuku could only moan, a continuous, shattered sound. “S’too much—I’m just—I’m a nasty, used-up slut—”

“You’re my nasty slut,” Toshinori growled into his ear, his voice thick with a possession that terrified him even as he claimed it. “Mine. Say it.”

“Yours! Dad’s nasty slut!” Izuku screamed, his body convulsing around the relentless invasion. “A filthy, two-hole whore!”

Katsuki’s laugh was a dark, approving rumble. “Good boy. Now tell him who taught you to take it like this. Who made this pussy so perfect?”

“Kacchan did!” Izuku sobbed, his head falling forward. “Kacchan made me perfect! Made me a—a fucktoy!”

Toshinori’s grip on Izuku’s thighs tightened, his fingers leaving pale imprints on the freckled skin. He was breathing in ragged, open-mouthed pants against his son’s shoulder. “You ruined him,” he gasped, not to Izuku, but to Katsuki over the boy’s head.

“I perfected him,” Katsuki corrected, his crimson eyes locked on Toshinori’s. He punctuated each word with a sharp, deep thrust that made Izuku jolt. “Look at him. He was born for this. You’re just finally seeing it.”

The dual penetration was a constant, overwhelming fullness, a stretching burn that blurred into blinding pleasure with every synchronized drive. Izuku felt his own arousal drip down his thighs, mixing with sweat and the slick from both men. The wet, slapping sounds filled the shadowed room.

“Gonna come,” Toshinori choked out, his hips stuttering. “Izuku—I can’t—”

“Don’t you dare,” Katsuki commanded, his own rhythm never breaking. “You don’t come until I let him. He’s my trigger. You’re just using my toy.”

Izuku whimpered, his own climax coiling tight and desperate in his gut. The denial made him clench violently around both cocks, drawing twin groans from the men. “Please, Kacchan, please let me—I need to—I’m gonna break—”

“You’ll break when I say,” Katsuki said, his voice dropping to a vicious, intimate whisper. “You’ll come when I tell you to thank your father for fucking your ass raw. Now, beg for it.”

"It's so deep," Izuku sobbed, the words a wet, broken chant against Katsuki's shoulder. "Dad's cock—it's so thick, it's—it's splitting me open inside. I can feel every vein, every pulse, right against my—my walls. It's rubbing me raw, it's making my pussy clench around you, Kacchan, I can't—I can't stop it—"

"Keep talking," Katsuki growled, his own thrusts becoming sharper, more deliberate, using Izuku's babbling as a metronome. "Tell him what his dick feels like."

"It's burning," Izuku gasped, his body jolting as Toshinori drove up into him with a particularly brutal angle. "It's so hot and it's stretching my ass so wide, I can feel it in my throat, I can taste it—it's filling me up, Daddy, you're filling up all the empty places—"

Toshinori let out a choked sound, part agony, part feral pride. His hands tightened on Izuku's thighs, his hips pistoning faster. "What else?" he demanded, his voice ragged.

"It's hitting so deep," Izuku cried, his head lolling back. "Every time you thrust, it—it shoves me down onto Kacchan's cock and I feel him in my pussy, in my stomach, and then you pull me back and I feel you dragging out, and my insides are just—just a wet, used-up sheath for you, just a warm hole for you to claim—"

Katsuki’s smirk was a blade. "He's learning." He shifted his grip, one hand fisting in Izuku's curls, yanking his head back to force eye contact with Toshinori. "Look at him. Look at what you're doing to your son. You're ruining him. And he's thanking you for it."

Toshinori’s bright blue eyes were glazed, drowning in the depravity. He stared at Izuku's wrecked, pleading face, at the tears cutting tracks through the sweat on his freckled cheeks. "My boy," he breathed, the words a prayer and a curse.

"Your slut," Katsuki corrected, his voice low and vicious. "Say it. While you're fucking his brains out. Tell him what he is."

"My slut," Toshinori echoed, the admission tearing from him. He drove up, hard, burying himself to the hilt, making Izuku scream. "My perfect, filthy little slut."

The dual rhythm was relentless, a brutal machinery of flesh. Izuku was a doll between them, his small body used as the junction of their competing hungers. The air was thick with the smell of sex, of sweat and salt and the musk of three bodies colliding.

"He's close again," Katsuki observed, his crimson eyes reading the tremors in Izuku's abdomen, the way his cunt fluttered and gripped. "Aren't you, Izuku? You're about to come all over my cock just from your father wrecking your ass."

"Please," Izuku whimpered, his dignity long gone, replaced by a raw, animal need. "Please, Kacchan, let me come. I'll be good, I'll be so good, I'll thank him, I'll worship his cock, just please—"

Katsuki leaned in, his lips brushing Izuku's ear. "Then thank him."

Permission. The word detonated in Izuku's spine. His back arched violently, a silent scream on his lips as the climax ripped through him. His pussy clenched in a rapid, milking rhythm around Katsuki's length, and a gush of warm fluid soaked both their thighs, his squirting release adding to the mess below. His ass clamped down on Toshinori's cock, the intense, rhythmic pressure tipping the man over the edge he'd been clinging to.

Toshinori shouted, a raw, broken sound, as his own orgasm seized him. He held Izuku aloft, impaled, as he emptied himself deep into his son's body, his thrusts turning into shallow, helpless jerks. The feeling of being filled from behind, combined with the aftershocks of his own pleasure, made Izuku sob, oversensitive and shattered.

Katsuki watched, his own movements slowing to a deep, possessive grind, drawing out Izuku's convulsions. He didn't finish. He simply kept his cock buried in the fluttering, soaked heat, a low rumble of satisfaction in his chest as he observed his handiwork: a father sobbing through his climax into his son, and the son, his student, taking it all, utterly destroyed and remade.

Katsuki’s hands replaced Toshinori’s on Izuku’s trembling thighs. “My turn,” he growled, and in one fluid, possessive motion, he pulled Izuku off his father’s softening cock and lowered the boneless boy onto his back across the couch cushions. The velvet was cool and sticky against Izuku’s sweat-slicked skin.

Toshinori stumbled back, his breath heaving, his pants around his ankles. He stared, hollow-eyed, at the glistening, used evidence of himself on his son’s body. “What are you—?”

“You’re in the way,” Katsuki said, not even looking at him. He nudged Izuku’s legs wider, his thumbs pressing into the tender inner flesh of his thighs. His crimson eyes drank in the sight: Izuku’s flushed, freckled skin, his pussy swollen and dripping, his asshole visibly open and wet. “Look at that. He’s still gaping for you. Pathetic.”

Izuku whimpered, oversensitive and raw. His vision swam. “Kacchan…”

“Shut up.” Katsuki spat into his palm, slicked his own massive cock, and without ceremony, pressed the thick head against Izuku’s loosened entrance. “This is what you saved for him? This ruined, sloppy hole?” He pushed forward, not with the brutal force from before, but with a slow, inexorable pressure that burned anew.

Izuku cried out, his back arching off the couch. “It’s—it’s different!”

“Of course it is,” Katsuki sneered, sinking deeper, his gaze locked on Izuku’s face. “My cock owns every part of you. Even the parts he thinks he took.” He seated himself fully, a deep, claiming grind that made Izuku’s toes curl. “Feel that? That’s me. In the place he just was. Erasing him.”

Toshinori made a wounded sound. He was still hard, his cock twitching traitorously at the sight. “Stop it.”

“You don’t give orders here,” Katsuki said, beginning to move with a slow, devastating rhythm. Each withdrawal was almost complete, each thrust a full, deep repossession. “You watch. You see what a real claiming looks like.”

Izuku’s hands fisted in the couch fabric. The stretch was different, more familiar yet somehow more intense, the blunt head of Katsuki’s cock rubbing directly against his oversensitive walls. “You’re so deep,” he babbled, the words slurred. “You’re in my stomach, you’re—you’re pushing his come deeper inside me—”

“Mixing us together,” Katsuki finished, his voice a dark thrill. He leaned over Izuku, caging him. “That’s what you are now. A cocktail of us. Our perfect little container.”

“Please,” Izuku sobbed, not knowing what he was asking for. His body was alight again, the exhaustion burned away by the specific, knowing friction of his teacher’s cock. “Please, Kacchan.”

“Please what?” Katsuki demanded, his pace quickening. The wet, rhythmic sound of flesh filled the room. “Use your words, slut.”

“Please make me come again,” Izuku begged, tears leaking from the corners of his eyes. “I need it. I’m empty without it. I’m just a hole, I’m your hole, please fill me up—”

Katsuki’s hand snaked between them, his thumb finding Izuku’s swollen clit. He pressed, hard, and circled. “You come when I tell you. And you’re going to look at him while you do it.” He grabbed Izuku’s jaw, forcing his head to the side where Toshinori stood, paralyzed. “Look at your father. Tell him who’s fucking you better.”

Izuku’s green eyes, glazed and desperate, found Toshinori’s shattered blue ones. “Kacchan is,” he moaned, the confession torn from him. “He’s deeper. He knows how to—how to fuck the come right out of me. He owns my ass, he owns all of me—”

Toshinori flinched as if struck, but his hand moved to his own cock, stroking himself slowly, compulsively.

“See?” Katsuki panted, his control fraying into raw hunger. His thrusts became punishing, the couch scraping against the floor. “He can’t look away. He loves seeing his son get ruined. He’s jerking off to it.”

“Daddy…” Izuku whispered, the title a blasphemy in the thick air.

That single word broke something in Toshinori. A strangled groan left his lips, and his strokes became frantic. “Izuku…”

“Now,” Katsuki snarled into Izuku’s ear. “Come for me. Show him what you look like when you’re mine.”

The command was a detonation. Izuku shattered, a silent scream on his lips as his body convulsed. His ass clenched rhythmically around Katsuki’s cock, his pussy gushed another wave of release that soaked the couch beneath him, and his vision whited out into pure, screaming sensation.

Feeling Izuku’s tight heat milk him, Katsuki’s own climax ripped through him with a guttural roar. He drove in one last, brutal time, holding himself deep as he emptied into the very core of the boy, his own release mixing with Toshinori’s inside Izuku’s trembling body.

Across the room, Toshinori came with a choked sob, his seed streaking the Persian rug, his eyes locked on the obscene, beautiful sight of his son being filled by another man.

For a long moment, there was only the sound of ragged breathing. Katsuki finally pulled out, leaving Izuku lying spent and dripping on the couch. His expression one of cold, profound satisfaction. He looked from the ruined boy to the broken man. “Lesson eleven,” he said, his voice quiet and final. “There’s no going back.”