The first thing Katsuki registered was the weight. The solid, warm weight of Izuku’s body pressed along his side, a head of green curls tucked under his chin. The second was the light. A pale, predawn grey seeping through the cabin’s single window, painting the rumpled sheets and the floorboards in washed-out tones. The third was the ache. A deep, satisfying ache in his muscles, and a different, sharper one between his legs, his cock already half-hard against the back of Izuku’s thigh.

He didn’t move. He breathed in the scent of pine and woodsmoke and sex, his son’s sleep-soft skin. His arm was pinned, gone numb under Izuku’s shoulders, but he’d cut the damn thing off before he’d wake him. Izuku’s breath hitched, a soft sigh against his collarbone. Katsuki’s jaw clenched. The plan, sharp and clear, cut through the morning haze. Marathon. All day.

With agonizing slowness, he shifted his free hand, groping across the nightstand until his fingers closed around his phone. He squinted at the blinding screen, thumb clumsy. One text. To Kirishima, his assistant coach for this trip.

“Me and Izuku are sick. Count us out for the day.”

He sent it. No explanation. No room for question. He dropped the phone, the soft thud on the wood loud in the quiet. The silence after felt different. Charged. The entire world outside this cabin—the camp, the team, the rules—officially locked out. He looked down at the mess of green hair. His nerd. His.

“Daddy?” The voice was muffled, thick with sleep.

“Shh.” Katsuki’s hand, the one that had been numb, came back to life in a rush of pins and needles. He flexed it, then brought it up to cradle Izuku’s head. “Go back to sleep.”

“You’re moving.” Izuku nuzzled closer, his leg shifting, the back of his knee brushing against Katsuki’s thickening cock. A sleepy, deliberate press. “You’re hard.”

“No shit.” Katsuki’s voice was a gravelly rumble in his chest. He didn’t deny it. He turned his head, buried his nose in Izuku’s hair. “Making up for lost time.”

Izuku hummed, a low, satisfied sound. He stretched against Katsuki, a full-body arch that made the sheet slip down to his waist. The cool morning air hit his skin, pebbling the soft, freckled curves of his chest. His nipples, dark pink and puffy, hardened instantly. Katsuki’s gaze locked on them. His thumb, of its own volition, stroked the line of Izuku’s jaw.

“You texted the camp,” Izuku murmured. It wasn’t a question.

“Yeah.”

“So we’re alone.”

“All day.” Katsuki’s hand slid from Izuku’s jaw, down the column of his throat, over the sharp dip of his collarbone. He palmed the swell of one tiny tit, his calloused thumb scraping over the stiff peak. Izuku gasped, his back bowing, pushing into the touch.

“Daddy…”

“I’m looking,” Katsuki growled, his voice raw. He was. Drinking in the sight of his son’s body in the grey light, marked from last night—the faint bruises on his hips from Katsuki’s grip, the love bite on his neck. His thumb circled Izuku’s nipple, rough and slow. “This what you wanted? Hm? My undivided attention?”

Izuku’s eyes fluttered open, green and still hazy. He nodded, biting his swollen lower lip. “Yes. Always.”

Katsuki leaned down, his mouth hovering just above Izuku’s. “You got it.” He didn’t kiss him. Not yet. He just breathed the same air, let the promise hang between them, a live wire in the cold, quiet cabin.

Katsuki closed the last inch of space and kissed him.

It wasn't gentle. It was hard, hungry, a claiming. His tongue pushed into Izuku’s mouth, tasting sleep and the faint, lingering mint of last night’s toothpaste. Izuku moaned into it, his hands flying up to tangle in Katsuki’s hair, holding on like he was drowning.

When he finally pulled back, both of them were breathless. Katsuki rested his forehead against Izuku’s, his thumbs stroking the sharp lines of his son’s hip bones. “Here’s the plan,” he whispered, his voice a dark, rough scrape against the quiet. “I’m gonna fuck you until you can’t remember your own name. Until all you know is my cock. You’re gonna come so many times you’ll forget how to count.”

Izuku shuddered, a full-body tremble that Katsuki felt against his palms. “Daddy…”

“I’m gonna start with my mouth,” Katsuki continued, his lips brushing Izuku’s as he spoke. “I’m gonna eat that sweet little pussy until you squirt all over my face. Then I’m gonna flip you over and fuck you from behind, hard enough you feel it in your throat.”

“Yes,” Izuku gasped, his hips twitching upward, seeking friction that wasn’t there.

“Then maybe I’ll put you on your knees. Make you suck me clean. See how much of me you can take.” Katsuki’s hand slid down, cupping Izuku between his legs. He was already soaking, heat and wetness seeping through the curls. Katsuki groaned. “Fuck. You’re dripping already.”

“It’s your fault,” Izuku breathed, rocking against his father’s hand. “You… you feel so big, even from last night. I’m sore. I can still feel you.”

“Good.” Katsuki pressed the heel of his hand down, a firm, grinding pressure that made Izuku cry out. “You’re gonna feel me for a week. Every time you sit, every time you walk to practice. You’re gonna remember who you belong to.”

“You,” Izuku said immediately, his green eyes wide and fixed on Katsuki’s. “I belong to you.”

Katsuki kissed him again, softer this time, a slow, deep slide of tongue that felt like a seal on the promise. He broke away, trailing his mouth down Izuku’s throat, over the bruise he’d left, down to his chest. He took one puffy nipple into his mouth, sucking hard, his tongue flicking the stiff peak.

Izuku arched, a sharp gasp tearing from his lips. His fingers tightened in Katsuki’s hair. “Don’t stop.”

“Wasn’t planning on it.” Katsuki switched to the other nipple, biting down just shy of pain, then soothing it with his tongue. He mapped the territory of his son’s body with his mouth—the soft freckled swell of each tiny tit, the sensitive dip of his sternum, the quivering plane of his stomach.

He moved lower, pushing Izuku’s thighs apart with his shoulders. The smell of him hit Katsuki then, musky and intimate, the scent of their coupling from last night and Izuku’s fresh, eager arousal. Katsuki’s cock throbbed, a painful, heavy ache against the sheet. He nuzzled into that hairless shaved pussy, breathing him in.

“Look at you,” Katsuki murmured, his voice thick. “Soaked for me. Always soaked for me.”

Izuku lifted his head, looking down the length of his own body, his face flushed. “Daddy, please…”

Katsuki didn’t make him wait. He lowered his mouth and licked a long, slow stripe from his son’s entrance all the way up to his swollen clit.

The sound Izuku made was pure wreckage. A choked-off scream that melted into a sob. His hips jerked off the bed. Katsuki held him down with a firm hand on his stomach and did it again. And again. He licked into him, tasting salt and heat and perfection, his tongue exploring every fold, every sensitive inch. He found the hard little nub of Izuku’s cock and sucked, gently at first, then harder.

Izuku was babbling, a stream of “please” and “Daddy” and “there, right there,” his hands fisting in the sheets. Katsuki could feel the tension coiling in his son’s belly, the muscles fluttering under his pressing hand. He pushed two fingers inside, curling them, and Izuku’s back bowed off the mattress.

“Gonna come?” Katsuki growled against him, the vibration making Izuku shriek.

“Yes—I’m—Daddy, I’m gonna—”

“Do it.” Katsuki redoubled his efforts, his mouth relentless, his fingers pumping. “Squirt for me. Let me feel it.”

Izuku came with a shattered cry, his body seizing. A hot gush of liquid hit Katsuki’s chin, his throat, the sheets below. It kept coming, wave after wave, until Izuku was gasping, spent, trembling through the aftershocks.

Katsuki rose up on his knees, wiping his mouth with the back of his hand. He looked down at his son, debauched and glistening in the morning light. His own need was a raw, screaming thing. He grabbed his aching cock, giving it a rough stroke. “That was just the first one,” he promised, his voice hoarse. “We’re just getting started.”

“Hands and knees,” Katsuki said, his voice rough from the taste of his son. He gave Izuku’s thigh a light slap. “Now. Present for me.”

Izuku scrambled, limbs clumsy with aftershocks. He turned over, the soaked sheets clinging to his skin, and got up on his hands and knees. He arched his back, pushing his ass up, his slick pussy on full display. He looked back over his shoulder, green curls sticking to his damp forehead. “Like this, Daddy?”

“Just like that.” Katsuki’s gaze was a physical weight. He knelt behind him, his big hands smoothing over the swell of Izuku’s ass, thumbs spreading him open wider. The morning light showed everything—the puffy, swollen lips, glistening and pink, the tight furl of his hole still relaxed from last night. “Fuck. Look at you. Still dripping my breakfast.”

He leaned forward and licked another slow stripe through Izuku’s folds, making him jolt and cry out. “Daddy—!”

“Just like that,” Katsuki repeated, his voice a low growl. He lined himself up, the broad, slick head of his cock nudging against Izuku’s soaked entrance. He didn’t push in. He just pressed there, a threatening, delicious pressure. “Tell me you want it.”

“I want it,” Izuku panted, pushing back against him, trying to take him inside. “Daddy, please, I want it so bad—”

“You want this fucking cock splitting you open?” Katsuki ground against him, smearing pre-cum and slickness. “This dirty cock that’s your father’s?”

“Yes! God, yes, I want your dirty cock, Daddy, I need it—”

Katsuki drove into him in one brutal, claiming thrust.

Izuku screamed, the sound raw and shattered in the quiet cabin. The stretch was immediate, overwhelming, a burning fullness that stole his breath. Katsuki buried himself to the hilt, his hips flush against Izuku’s ass, his low-hanging balls tight against his son’s skin. He held there, letting Izuku feel every inch, every throbbing vein.

“Fuck,” Katsuki grunted, his own breath coming in ragged pulls. “Tighter than last night. Squeezing me like a fucking vise.”

He pulled back almost all the way, then slammed home again. The slap of skin on skin was loud, obscene. He set a punishing rhythm immediately, no warm-up, no mercy. Each thrust rocked Izuku forward on his hands, his ass taking the impact, the wet, sucking sound of their joining filling the air.

“That’s it,” Katsuki snarled, one hand fisting in Izuku’s green curls, pulling his head back. “Take it. Take your Daddy’s cock. You begged for this, you little slut. You joined my fucking team for this.”

“I did,” Izuku sobbed, tears leaking from the corners of his eyes. The pain was sharp, a bright edge that melted into a deep, aching pleasure with every savage stroke. “Wanted you—only ever wanted you—”

Katsuki’s other hand snaked around Izuku’s hip, his fingers finding his son’s swollen clit. He rubbed rough, tight circles, matching the pace of his thrusts. “Gonna make you come on my dick. Gonna feel that little pussy milking me while I’m balls deep in my own son.”

The dual sensation was too much. Izuku’s vision blurred. His arms gave out and he collapsed onto his forearms, his face pressed into the musky sheets, his ass still high in the air for Katsuki’s use. The change in angle made Katsuki groan, his thrusts going deeper, hitting a spot that made white fireworks burst behind Izuku’s eyelids.

“There! Daddy, right there, please—”

“I know where it is,” Katsuki grunted, hammering that spot relentlessly. His own control was fraying. Sweat dripped from his chin onto Izuku’s back. “I know your body better than you do. Come for me. Now.”

The command, the impossible fullness, the rough fingers on his clit—it broke him. Izuku came with a broken wail, his pussy clenching and fluttering around the massive cock impaling him. A fresh gush of fluid soaked Katsuki’s thighs, the sheets beneath them.

Katsuki fucked him through it, his rhythm turning erratic, brutal. “That’s it, soak me, you perfect fucking slut,” he rasped.

“Not yet,” Katsuki gritted out, his voice strained. He pulled out with a wet, slick sound, his cock springing free, thick and purple and dripping. He stroked himself roughly, his jaw clenched tight against the tide of his own release. “Not fucking yet.”

“Daddy?” Izuku whimpered, his body trembling, empty and clenching around nothing. “Why’d you stop?”

“Because I said so.” Katsuki’s breath was ragged. He gave his cock a few more punishing strokes, then forced his hand away. “On your back. Now. I want you to watch.”

Izuku collapsed onto his back, limbs boneless. He watched, wide-eyed, as Katsuki knelt over him, positioning himself between his spread thighs. The morning light caught the sheen of sweat on his father’s chest, the brutal cut of his abs. Katsuki guided himself back to Izuku’s entrance, the head nudging insistently.

“Look down,” Katsuki commanded, his voice a dark rasp. “Watch what happens to you when I’m inside.”

Izuku’s gaze dropped to his own stomach, to the soft, freckled plane below his navel. Katsuki pushed in, slow and inexorable, and Izuku’s mouth fell open. He could see it. The distinct, terrifying bulge forming under his skin with every inch his father claimed. A visible, obscene outline of the massive cock splitting him open.

“Oh my god,” Izuku breathed, his hands flying to his own belly, pressing against the protrusion.

“That’s me,” Katsuki growled, hilting himself fully. He rocked his hips, a shallow, grinding motion that made the bulge shift. “That’s your Daddy, buried in your guts. See how deep you take me?”

“I see it,” Izuku sobbed, equal parts horror and rapture. He was stretched so full he felt faint. The pressure was everywhere, a claiming so deep it felt like possession. “You’re so big, Daddy.”

Katsuki began to move, pulling back until just the tip remained, then driving home. Each thrust punched the air from Izuku’s lungs and made the bulge in his stomach reappear, a brutal, rhythmic distortion of his body. The wet slap of their joining was constant, a filthy percussion. Izuku couldn’t look away.

“Your perfect little slut-belly,” Katsuki snarled, his pace relentless. He leaned down, bracing himself over Izuku, his shadow swallowing him. “Made for showing off my cock. You think any other man could do this to you? Could fuck you so deep you look pregnant with him?”

“No! No one, only you, only ever you—” Izuku choked out. His own hands were still pressed to his stomach, feeling the hard length of his father move inside him. The sensation was maddening. He was so full he could taste it.

Katsuki’s rhythm faltered, his control slipping. He fucked into him harder, faster, the bedframe slamming against the cabin wall. “Gonna ruin you,” he promised, sweat dripping from his brow onto Izuku’s cheek. “Gonna fuck you so many times today you’ll feel me in your throat. You’ll walk crooked for a week, and every time you wince, you’ll remember it’s because your father’s cock is all you can fit.”

Izuku’s body arched off the bed as another gush of fluid soaked the space between them, his pussy clenching in a violent, squirting orgasm around the cock that impaled him. “D-Daddy!”

“Fuck, yes, soak me,” Katsuki growled, his thrusts turning brutal and deep, pounding the liquid deeper into the mess. “You hear me, Izuku? You want Daddy to breed this filthy little pussy? Want me to pump my cum so deep into my son it never comes out?”

“Yes! Breed me, Daddy, please, fill me up, I want it—” Izuku sobbed, his fingers digging into his own distended stomach.

“Gonna own you,” Katsuki snarled, his rhythm fracturing into something primal. His hips pistoned, the wet slap of skin echoing off the wooden walls. “Gonna knock you up with my kid even if your body can’t take it. You’ll walk around full of your father’s seed all day, knowing what you are.”

“What am I?” Izuku gasped, his eyes glazed, completely broken open.

“You’re my breeding slut,” Katsuki rasped, his voice cracking with the strain of holding back. “My perfect, fucking son-shaped whore.”

The words unspooled the last of Katsuki’s control. With a ragged shout, he drove in one final, devastating time and held, his body locking as he came. Izuku felt it—the hot, pulsing flood deep inside him, a claiming so visceral it stole his breath. His own oversensitive pussy fluttered weakly around the intrusion, milking the cock that filled him.

Katsuki collapsed forward, bracing his weight on trembling arms, his forehead dropping to Izuku’s sweat-slicked shoulder. He stayed there, buried to the hilt, panting harshly into his son’s neck as his cock twitched, depositing the last of his release. The only sounds were their ragged breathing and the wet, messy drip between Izuku’s thighs.

After a long minute, Katsuki shifted, pulling out slowly. A thick trickle of white immediately seeped from Izuku’s used entrance, painting his inner thigh. Katsuki’s eyes tracked it, dark with satisfaction. He swiped two fingers through the mess, gathering the mixed fluids.

“Look at that,” he murmured, his voice hoarse. He held his glistening fingers in front of Izuku’s dazed face. “That’s me. In you. Where I belong.”

Izuku nodded, exhausted, and without being told, he opened his mouth. Katsuki pushed his fingers inside, letting Izuku taste their joining. “Good boy,” Katsuki said, his tone shifting into something dangerously close to soft. He pulled his fingers free and smoothed Izuku’s damp curls back from his forehead.

“We’re just getting started, nerd.”