The bedroom was stark, dominated by a large bed. Izuku's back hit the cool cotton, and the scent of Katsuki—clean, sharp, male—enveloped him completely. This was the inner sanctum, where the teacher vanished and only the predator remained. When Katsuki's weight settled over him, the world shrank to the size of this mattress, this claim. Izuku understood: here, his training would be completed, and his old self would be erased forever.

Katsuki braced himself above him, a cage of muscle and heat. His crimson eyes scanned Izuku’s face, the freckles stark against his pale skin. “Look at me.” Izuku did. He always did. “You came here.”

“Y-yes.”

“Say it.”

Izuku’s throat worked. “I came to you, Kacchan.”

The name, spoken here in the dark, was a lit match. Katsuki’s control, usually so cold, flickered with something hotter. Raw. His hips pressed down, and Izuku felt it—the hard, thick line of him still confined in his trousers, a promise against Izuku’s thigh. “This is where you learn what that means.”

Katsuki’s hands were methodical. He pushed Izuku’s shirt up, baring his small chest, his thumbs brushing over the puffy brown nipples until they peaked into tight buds. Izuku gasped, back arching off the bed. “Sensitive,” Katsuki noted, his voice a low growl. “Good.” He leaned down and took one into his mouth, sucking hard, his tongue rough and demanding.

The sensation was a lightning bolt, straight to Izuku’s core. He cried out, his hands flying up to tangle in Katsuki’s spiky hair. He was already wet, he could feel the slick heat soaking through his own pants, a humiliating, eager leak. Katsuki moved to the other nipple, biting down just enough to make Izuku whimper. “You’re dripping for me already, aren’t you?”

“I… I can’t help it.”

“You don’t have to help it.” Katsuki pulled back, his gaze burning. “You just have to take it.” He hooked his fingers in the waistband of Izuku’s sweats and underwear and pulled them down in one rough motion. The cool air hit Izuku’s exposed skin, followed by the searing heat of Katsuki’s stare. He was laid bare, his small, wet cunt completely exposed, his clit swollen and desperate.

Katsuki’s hand slid down Izuku’s trembling stomach and cupped him. His fingers slid through the slickness effortlessly. “Fuck,” Katsuki breathed, the curse reverent. He gathered the wetness on his fingers and brought them to Izuku’s lips. “Taste. Taste how ready you are for me.”

Izuku obeyed, his tongue darting out to lick his own salt-musk from Katsuki’s skin. It was intimate, degrading, perfect. Katsuki watched him, his own breathing deepening. Then he pushed Izuku’s thighs apart, his grip firm on the soft flesh. He looked his fill, his eyes tracing every fold, every glistening inch. “Virgin cunt,” he said, almost to himself. “My virgin cunt.” He pressed a single, blunt finger against Izuku’s entrance. The pressure was immense. “This is where I’m going to ruin you.”

He didn’t push in. Not yet. He just held the pressure there, letting Izuku feel the threat of it, the inevitability. Izuku panted, his hips trying to push down, to get more, but Katsuki held him still. “Please,” Izuku whispered, the word torn from him.

“Please what?”

“Please… Kacchan.”

Katsuki’s finger slid inside, just the tip. The stretch was immediate, a burning fullness that made Izuku cry out. It was nothing compared to what was coming. Katsuki leaned close, his lips brushing Izuku’s ear. “You’ll take all of me. Every inch. You’ll scream for it. And when I’m done, you won’t remember a time when you weren’t mine.” He pushed his finger in to the knuckle, and Izuku’s world dissolved into a white-hot point of sensation, his body clenching around the invasion, welcoming it.

Katsuki added a second finger alongside the first, and the stretch became a burning, undeniable ache. Izuku gasped, his back bowing off the bed, his cunt fluttering wildly around the twin invasion. "Breathe," Katsuki commanded, his voice a rough scrape against Izuku's ear. He didn't move, just let Izuku feel the full, splitting width of him. "Feel how tight you are. How you have to open for me."

"It's... it's too much," Izuku choked out, tears pricking his eyes.

"It's not enough." Katsuki began to move his fingers, a slow, torturous scissoring motion that dragged a ragged cry from Izuku's throat. The wet sound was obscenely loud in the dark room. "This is just my hand, Izuku. My cock is twice this thick. You understand?"

Izuku could only nod, his mind white with sensation. The pain was sharp, but beneath it, a deeper, hotter current of pleasure pulsed, syncing with the rhythm of Katsuki's thrusting fingers. His hips began to move on their own, fucking himself on the intrusion, seeking more of that devastating friction.

"Look at you," Katsuki growled, his breath hot on Izuku's neck. "Your greedy little cunt is sucking my fingers in. You want it to hurt, don't you?"

"I don't know," Izuku sobbed, his hands clawing at the duvet.

"You do." Katsuki curled his fingers, pressing deep into a spot that made Izuku see stars. A gush of wetness soaked Katsuki's hand and the sheets beneath them. "Your body knows. It's begging for it." He sped up his thrusts, the pace relentless, the stretch constant. The burning was transforming, becoming a molten heat that pooled in Izuku's belly, tightening with every pass over that perfect, brutal spot.

"Kacchan, I'm—"

"Not yet." Katsuki stilled his hand, buried to the knuckles. Izuku whimpered, his climax hovering just out of reach, agonizing. "You don't come until I'm inside you. You don't come until I say." He slowly withdrew his fingers, and Izuku felt empty, gaping, aching. The cold air hit his soaked flesh, and he shuddered.

Katsuki moved off the bed, and Izuku heard the rustle of clothing, the sharp zip of a fly. He turned his head, his vision blurred. Katsuki stood beside the bed, naked now, his cock jutting out thick and heavy and impossibly large in the dim light. It was flushed dark, the head glistening, veins standing in stark relief. Izuku's mouth went dry.

"Look," Katsuki said, wrapping a fist around his length. He gave himself a slow, firm stroke, his eyes locked on Izuku's. "This is what you asked for. This is what you came here for."

He climbed back onto the bed, kneeling between Izuku's spread thighs. He used the head of his cock to nudge through Izuku's slick folds, smearing the wetness, teasing his swollen clit. The contact was electric. Izuku jerked, a broken sound escaping him.

"Please," Izuku whispered, the word raw. "Please, Kacchan. Now."

Katsuki leaned forward, bracing his weight on his hands, caging Izuku completely. He positioned himself, the broad tip pressing insistently against Izuku's entrance. The pressure was immense, a blunt, unyielding force. "This," Katsuki said, his voice trembling with a restraint Izuku had never heard before, "is where you become mine."

He pushed in slowly.

The stretch was a burning, splitting reality. Izuku’s breath hitched, then stopped entirely. His body resisted, a tight, virgin ring of muscle clenching in panic against the relentless, blunt pressure. Katsuki didn’t stop. He leaned his weight forward, a millimeter at a time, and Izuku felt himself being opened, torn, reshaped.

“Breathe,” Katsuki gritted out, his own voice strained. Sweat dripped from his temple onto Izuku’s chest. “Breathe through it.”

Izuku gasped, a ragged, wet sound. The pain was a white-hot line, but beneath it, a deeper, shocking fullness bloomed. He could feel every ridge, every thick inch as it breached him, a living invasion. “It’s… it’s too big.”

“It’s mine,” Katsuki corrected, his hips sinking another impossible fraction. The stretch intensified, a burning ache that made Izuku’s vision swim. “And you’re taking it. All of it.”

He paused, buried halfway, letting Izuku feel the sheer girth of him. The sensation was overwhelming—a devastating fullness that bordered on pain, a claiming so complete it felt like truth. Izuku’s cunt fluttered wildly around the intrusion, trying to accommodate, slickness easing the brutal slide.

“Look at me,” Katsuki commanded. Izuku’s tear-filled eyes found his. Katsuki’s face was a mask of fierce concentration, his usual cold control burned away by raw, hungry need. “You feel that? That’s me. Inside you. Where I belong.”

He pushed forward again, a slow, relentless advance. The burning crested, and for a second, Izuku thought he might break. Then, with a final, deep thrust, Katsuki’s hips met his, and he was fully sheathed. The feeling was catastrophic. Izuku cried out, a broken sound that was half-sob, half-relief. He was full, impossibly full, stretched to his limit around Katsuki’s massive cock.

Katsuki went still, a tremor running through the muscles of his arms. He was breathing hard, his crimson eyes locked on Izuku’s. “Fuck,” he whispered, the word reverent. “You’re so tight. Like a fucking vise.”

He didn’t move. He let Izuku feel it—the complete occupation, the heat, the intimate pulse of him buried deep. The initial sharp pain was fading, replaced by a throbbing, aching fullness that was already twisting into something else. Izuku’s hips gave a tiny, involuntary jerk.

“Hurts?” Katsuki asked, his voice low.

“Y-yes.”

“Good.” He withdrew, just an inch, the drag exquisite and brutal. Then he pushed back in, a slow, deep roll of his hips. “It’s supposed to hurt. The first time. So you remember who did this to you.”

He set a pace that was agonizingly slow, each thrust a deliberate, grinding conquest. Izuku could feel every inch of the slide, the friction burning a path straight to his core. His own pleasure was building on a delay, a slow heat igniting in the wake of the pain. His nails dug into Katsuki’s shoulders.

“Kacchan,” he whimpered, the name a plea for mercy or for more, he didn’t know.

“Say it again.”

“Kacchan.”

Katsuki’s rhythm stuttered. He drove into him harder, faster, the slow burn erupting into a consuming fire. The wet, slapping sound of their bodies filled the room, a rhythm punctuated by Izuku’s sharp cries and Katsuki’s ragged breaths. The pain was gone, burned away, replaced by a pleasure so intense it bordered on violence. Each thrust hammered into that deep, perfect spot, lighting Izuku’s nerves like a fuse.

“You’re mine,” Katsuki growled, his voice raw with possession. “This cunt is mine. Your mouth is mine. Every fucking gasp is mine.”

Izuku could only nod, his world narrowed to the point where their bodies joined, to the searing heat of Katsuki’s skin against his, to the devastating friction that was coiling his stomach into a tight, screaming knot. He was close, so close, the pressure building like a storm.

“Kacchan, I’m gonna— I can’t—”

“Come.” The command was a gunshot in the dark. “Come on my cock. Now.”

Izuku’s orgasm hit like a seizure, a violent, arching release that tore a scream from his throat. His cunt clenched in frantic, milking pulses around the thick invasion, and a hot gush erupted from him, soaking Katsuki’s lower abdomen and the sheets beneath them in a shocking, continuous flood. It wasn't a trickle. It was a fountain, just as promised, a physical surrender so complete it left him gasping and seeing stars.

“Fuck, look at that,” Katsuki snarled, his rhythm never breaking. His thrusts turned punishing, the wet, obscene slap of his balls against Izuku’s ass echoing in the room. “You’re a fucking mess. A little piss-slut fountain just for me.”

“K-Kacchan, too much—” Izuku sobbed, overstimulated, his body trembling through the aftershocks.

“It’s not enough.” Katsuki drove into him harder, his control shattered, his hips pistoning in a brutal, filthy rhythm. The broad head of his cock slammed deep with every thrust, battering a spot inside that felt like his cervix, a bright, shocking pain-pleasure that made Izuku’s toes curl. “You take it. You take all of it, you greedy little cunt.”

His words were a filthy, hot stream against Izuku’s ear. “My perfect fuckhole. Trained just for this. You feel that? That’s my cock rearranging your insides. Making room.”

Izuku could only nod, his cries reduced to ragged hitches of breath. The squelching sounds were loud, obscene, proof of how wrecked he was, how thoroughly used. Katsuki’s sweat dripped onto his face, mixing with his tears.

“Who do you belong to?” Katsuki demanded, his pace becoming erratic, desperate.

“Y-you! Kacchan!”

“Say it. Say what you are.”

“Y-your… your fuckhole,” Izuku gasped, the crude word burning his tongue even as it sent a fresh jolt of heat through his spent body.

“My cock sleeve. My little breeding toy.” Katsuki’s voice was guttural, his thrusts losing their rhythm, becoming deep, grinding slams. His fingers dug into Izuku’s hips hard enough to bruise. “Gonna fill you up. Mark you inside. You feel me getting close? You feel my cock throbbing in your little slut cunt?”

Izuku did. He felt the twitch, the pulse, the impossible fullness growing even more intense. He wrapped his legs around Katsuki’s waist, pulling him deeper, a silent plea for the final claim.

Katsuki’s groan was raw, animal. He buried his face in Izuku’s neck, his hips stuttering. “Take it. Take my cum. Your first. Mine.”

He slammed home one last time and held, his body rigid. Izuku felt the hot, sudden flood deep inside, a searing release that seemed to go on and on, filling the emptiness Katsuki had carved. Katsuki shuddered violently above him, a low, continuous growl vibrating against Izuku’s skin.

For a long moment, there was only the sound of their harsh breathing and the wet, intimate silence between them. Katsuki was still inside him, softening slightly but present, a heavy, claiming weight. He lifted his head, his crimson eyes hazy and satisfied. He looked down at the mess between them—the sweat, the spend, the evidence of Izuku’s release soaking the sheets. A slow, possessive smile touched his lips.

“Lesson five,” he murmured, his voice hoarse. “Complete.”