Katsuki was still breathing hard, his spent cock lying heavy against his thigh, when Izuku shifted. The sleeping bag stuck to their skin with sweat and other things.

Izuku’s green eyes were locked on him, huge and begging. He didn’t speak. He just let his own hand slide down the flat plane of his stomach, through the dark curls, and between his legs.

“Look,” Izuku whispered, his voice ragged from use.

Katsuki’s breath hitched. He was watching. He couldn’t look away as Izuku’s fingers, slender and curious, found his own slick folds. A low, shaky moan left Izuku’s lips as he touched himself, spreading the wetness there.

“I used to think about this,” Izuku said, the words tumbling out in a rushed, breathless stream. “When I was a kid. After my baths. I’d… I’d touch myself in my room and pretend it was you finding me.”

Katsuki made a sound like he’d been punched. “Izuku.”

“I’d pretend you were mad.” Izuku’s fingers circled his clit, his hips giving a tiny jerk. His other hand came down, spreading himself open, offering the glistening, pink view to his father’s stormy eyes. “That you caught me being bad. That you had to… to punish me.”

“Stop,” Katsuki growled, but it was weak. His cock, softening just moments ago, gave a distinct, heavy throb against his leg.

“I wanted you to rape me.” The word, filthy and precise, hung in the hot air. Izuku’s breath hitched as he pushed two fingers inside himself, shallow. “When I was fourteen. Fifteen. I’d imagine you just… coming into my room. Pinning me down. Telling me I asked for it. Fucking me so hard I couldn’t walk after.”

Katsuki’s hand shot out, wrapping around Izuku’s wrist, stilling his movements. His grip was iron. “You don’t know what you’re saying.”

“I do.” Izuku’s eyes were bright, feverish. “I wanted my daddy to ruin me. I dreamed about your cock. How big it was. How it would hurt. I wanted it to hurt.”

With a rough tug, Katsuki pulled Izuku’s hand away, replacing it with his own. His calloused thumb brushed over Izuku’s soaked opening, and Izuku cried out, back arching. “Like this?” Katsuki’s voice was gravel, raw with a hunger that mirrored his son’s confession. “You wanted me to just take it?”

“Yes.” Izuku spread his legs wider, his thick thighs trembling. “Just like that. Please.”

Katsuki leaned over him, his shadow swallowing Izuku whole. His other hand came down to brace himself by Izuku’s head. His erection, now fully hard and leaking, pressed against Izuku’s inner thigh. “You’re sick,” he breathed, but he was rocking his hips, smearing pre-come against his son’s skin.

“I’m yours,” Izuku gasped, reaching up to clutch at Katsuki’s shoulder. “I’ve always been yours. Daddy. Please. Do it. Do what I dreamed about.”

Katsuki’s control shattered. He guided the thick head of his cock through Izuku’s drenched folds, a low, animal groan ripping from his chest at the sensation. He pressed forward, just an inch, the tight, clenching heat of Izuku’s body yielding around him. Izuku whimpered, nails digging into Katsuki’s back.

“This what you wanted, you filthy kid?” Katsuki snarled, his hips trembling with the effort of not slamming home. “Your old man fucking you raw in some tent?”

“Yes,” Izuku sobbed, pushing his hips up, trying to take more. “Yes, Daddy. Please. I’ve been empty for you. I’ve always been empty for you.”

“Tell me the rest,” Katsuki snarled, his voice a brutal scrape in the charged air. He didn’t thrust. He held himself there, just the swollen head of his cock breaching Izuku’s body, a hot, impossible pressure. “The dirty details. Now.”

Izuku whimpered, his whole body trembling around that partial invasion. “Daddy—”

“Now.” Katsuki pulled back, popping the tip free with a wet sound that made Izuku cry out at the loss. He slid it back, just an inch, the thick crown stretching him open before withdrawing again. A tease. A torment. “You wanted me to rape you. So talk. What did your sick little kid brain imagine?”

“I—I imagined you’d be angry,” Izuku gasped, his hips chasing the fleeting pressure. “That you’d smell the shower on me. That you’d know what I’d been doing in there.”

Katsuki rocked forward again, a shallow, punishing push. “And?”

“And you’d throw me on my bed,” Izuku rushed out, his words slurring as Katsuki’s cockhead rubbed a torturous circle against his soaked opening. “You wouldn’t say anything. You’d just use your belt… tie my wrists to the headboard.”

“Fuck.” Katsuki’s control was a visible tremor in his biceps. He pushed in again, slightly deeper this time, making Izuku’s breath stutter. “Then what?”

“You’d spread my legs open. Look at me.” Izuku’s eyes were glazed, locked on his father’s furious, hungry face. “You’d call me a slut. Your own little slut.”

Katsuki’s hips jerked involuntarily, sheathing another inch inside the clenching, desperate heat. A strangled groan was torn from him. “You are.”

“And then you’d just… take it.” Izuku’s voice broke into a sob as Katsuki withdrew completely, leaving him empty and shaking. “No lube. No prep. Just your cock, because I deserved it for being so bad, for wanting my dad—”

Katsuki slammed back in, not fully, but hard enough to punch the air from Izuku’s lungs. “You did deserve it,” he growled, his rhythm becoming a brutal, shallow pistoning—in two inches, out, in three, out—each penetration a sharp, bright shock. “Dreaming about your father’s dick. Letting yourself get this wet for it.”

“I couldn’t help it,” Izuku wept, his hands scrabbling at Katsuki’s sweaty back. “I’d touch myself pretending it was you, Daddy, I’d come thinking about you filling me up—”

That undid him. Katsuki’s careful, torturous pace shattered. With a raw, gut-deep sound, he drove himself forward, burying his entire length in one relentless, burning thrust.

Izuku screamed. It was a sound of pure, shattered relief, his body arching off the sleeping bag, his inner muscles clamping down in a violent, welcoming spasm around the thick intrusion. The stretch was immense, a breathtaking burn that morphed instantly into a devastating fullness.

Katsuki froze, buried to the hilt, his forehead dropping to Izuku’s shoulder. His breath came in ragged, hot bursts against Izuku’s damp skin. “Christ,” he panted. “You’re so… fucking tight.”

“It’s yours,” Izuku whispered, his voice wrecked. He wrapped his thick thighs around Katsuki’s waist, locking him in. “It’s always been yours. Do it. Please. Ruin me like you promised. Ruin me,” Izuku begged, his voice a broken thing against Katsuki’s shoulder. “Please, Daddy. Fuck my pussy. Rape my pussy, Daddy, please—”

Katsuki’s answer was a brutal, withdrawing shove and a slam back in that stole the air from the tent. He set a punishing rhythm, each thrust a deep, claiming piston that punched choked sounds from Izuku’s throat. The wet, slapping noise of their bodies filled the hot, confined space.

“This,” Katsuki grunted, his voice thick and dark, “this cunt was made for this.” He drove into him, his hips snapping forward with a force that shifted Izuku up the sleeping bag. “Made to take me. I felt it the first time I held you. Knew you were born for my cock.”

Izuku sobbed, his nails raking down Katsuki’s sweat-slicked back. “Yes! Yes, Daddy, I was! I was born for you!”

Katsuki’s hand fisted in Izuku’s green curls, yanking his head back to expose his throat. He leaned down, his lips against Izuku’s ear. “This is why I wanted a kid. So I could fuck him raw. So I could ruin him just like this.” The words were a vile, hot whisper, a confession that seemed to shock even him as he pounded into his son’s body.

Izuku screamed, a sound of pure, unraveling ecstasy. His hips met every savage thrust, his tight channel clenching and fluttering around the thick invasion. “Harder! Please, Daddy, harder! It’s yours, it’s always been yours!”

“Mine,” Katsuki snarled, his control gone, replaced by a feral, possessive hunger. He changed the angle, lifting Izuku’s hips higher, driving down into him with a depth that made Izuku’s eyes roll back. “Your sick, little kid dreams… this is what you wanted. Your daddy using you. Taking what’s mine.”

“I’m yours!” Izuku chanted, a litany of submission. “Your slut, your kid, your cunt—Daddy, I’m gonna cum, please, let me cum—”

Katsuki’s pace turned erratic, brutal, his own climax coiling tight in his gut. He released Izuku’s hair, his hand sliding between their sweat-slicked bodies, his thumb finding Izuku’s swollen clit. He pressed down, a rough, circling torment. “Come, then,” he commanded, his voice shattered. “Come on your father’s dick. Show me how bad you needed it.”

Izuku’s mind shattered. The rough press of his father’s thumb on his clit and the deep, relentless pounding inside him fused into a white-hot detonation behind his eyes. His back arched off the sleeping bag, a silent scream stretching his mouth open before sound ripped out—a raw, guttural cry that didn’t sound human. His eyes crossed, vision blurring into static, and his tongue lolled out between his parted lips, slick with spit.

His orgasm wasn’t a wave; it was a seizure. His pussy clenched in a violent, rhythmic spasm around Katsuki’s buried cock, each tight flutter milking him desperately. Then he squirted, a hot, sudden gush that soaked Katsuki’s lower abdomen and the sleeping bag beneath them, the sound a sharp, wet slap in the humid air.

The intense, clenching pressure was the final trigger. Katsuki snarled, his hips stuttering before he drove in one last, deep time and held, grinding against Izuku as his own climax tore through him. He came inside his son, a hot, pulsing flood that filled the tight, convulsing channel, his cock throbbing with each jet.

For a long moment, there was only the sound of their ragged, gasping breaths and the wet drip of spent fluids. The heat between their bodies was a slick, shared misery.

Katsuki’s weight collapsed onto him, then immediately jerked back as if burned. He pulled out, the wet, sloppy sound obscene in the sudden silence. He stared down between Izuku’s splayed, trembling thighs, watching his own spend begin to leak out, mixing with Izuku’s release on the ruined sleeping bag.

“Fuck,” Katsuki breathed, the word hollow.

Izuku’s vision cleared slowly. He looked down at the mess, at the evidence dripping from his body. The animal haze retreated, and a cold, sharp clarity took its place. “Oh,” he whispered.

Katsuki’s head snapped up. “Oh? What ‘oh’?”

“I… I’m not on anything,” Izuku said, his voice thin. “The pill… it made me sick. I stopped before graduation.”

“You stopped.” Katsuki’s voice was flat, dead.

“And today…” Izuku swallowed, his throat clicking. “It’s not a safe day…”

Realization dawned on them both.