The tent was dark, soft-lit by a single lantern turned low. The air inside was still and heavy with the day’s heat, smelling of nylon and dirt and the two of them. Katsuki sat against his pack, a beer dangling from his fingers. Izuku sat cross-legged, picking at a loose thread on his sleeping bag. The silence wasn’t comfortable. It was waiting.

“How long?” Katsuki’s voice was gravel, worn thin from too many cigarettes that day. He didn’t look at him.

Izuku’s fingers stilled. “What?”

“You heard me. How long have you been… like this.”

Izuku swallowed. The lantern light caught the flutter in his throat. “A long time.”

“Define it.”

“I was ten.”

The beer bottle stopped halfway to Katsuki’s mouth. He set it down slowly, the plastic groundsheet crinkling under the base. He turned his head. His storm-colored eyes were black in the low light. “Say that again.”

“The first time I knew. I was ten.” Izuku’s voice was a whisper, but it didn’t waver. He looked at his father’s hands. “You were fixing the sink. You had your shirt off. It was summer. You were sweaty.”

Katsuki’s breath left him in a slow, controlled exhale. Horror washed over his face, cold and stark, erasing the heat of the last few days. “You were a child.”

“I know.”

“A fucking child, Izuku.” His voice dropped, low and dangerous. “That’s not… that’s sick.”

“I know!” Izuku’s head snapped up, his green eyes wide and wet. “Do you think I don’t know that? I’ve known it was sick since I was ten. It didn’t stop me. It never stopped.”

Katsuki stared. His jaw worked. He looked like a man witnessing a car crash in slow motion, unable to look away from the twisted metal of his own life. “What did you… what did you think about? At ten.”

Izuku’s expression shifted. The defiance bled out, replaced by something distant, soft. His shoulders rounded. He looked down at his own lap, and when he spoke again, his voice was different. Higher. Thinner. A child’s voice. “I thought about your hands. They were so big. I wanted you to pick me up.”

A violent shiver went through Katsuki. He didn’t move.

“I had a dream,” the little-boy voice continued, dreamy and confessional. “You came into my room at night. You said you were checking for monsters. You touched my hair. Your hand was so warm, Daddy.”

The word landed in the tent like a physical blow. Katsuki flinched.

Izuku looked up through his lashes, his face a perfect mirror of childish innocence and corrupted want. “I got all squirmy. I didn’t know why. I just knew I wanted you to stay. I wanted…” He bit his lip, a childish gesture. “I wanted you to hold me down. I didn’t know the words for it then. I just knew I wanted it to be you.”

“Stop,” Katsuki rasped. But his command had no force. It was the plea of a drowning man.

“Do I have to stop, Daddy?” Izuku whispered, the little boy pleading now. He uncrossed his legs, knees falling apart slightly on the sleeping bag. “I was a bad boy. I thought such bad things. I used to touch myself in bed and pretend it was your hand.”

Katsuki’s own hand clenched into a fist. His knuckles were white. A muscle ticked in his jaw. The horror was still there, a cold pit in his stomach. But beneath it, under the shock and the revulsion, a different heat was igniting. A treacherous, damning heat that gathered in his groin, thick and urgent.

Izuku’s wide green eyes dropped to Katsuki’s lap. The growing bulge there was unmistakable, straining against the worn fabric of his jeans. A slow, secret smile touched Izuku’s lips. He crawled forward, the sleeping bag rustling under his knees. “I’m sorry, Daddy,” he whispered, his voice a high, contrite whine. “I’m such a bad boy for telling all those icky stories.”

He didn’t wait for permission. He laid his head down in Katsuki’s lap, his cheek pressing against the hard heat. The position was a perfect mirror of a thousand childhood moments, seeking comfort after a nightmare. Katsuki went utterly rigid.

“See?” Izuku cooed, nuzzling him. “Daddy’s willy is all big. It used to scare me when I was little and I felt it. Now it just makes my tummy feel all… tingly.” He looked up, his face a mask of childish innocence. “I’m having those same tingles right now, Daddy. Down in my… kitty.”

“Izuku,” Katsuki warned, the name a strained gasp. His hands hovered at his sides, clenched into fists, unsure whether to push him away or pull him closer.

“It’s true!” Izuku insisted, the baby talk layering over his words. “My princess parts get all achey when I think about you. Just like when I was ten. I can show you, Daddy. I can show you how I used to make the tingles go away.”

His own hands, small and deft, slipped between his thighs. He kept his head in Katsuki’s lap, watching his father’s face as his fingers found the hem of his shorts, then slipped beneath. His breath hitched, theatrically. “Oh… it’s all slippery. My cunny gets so wet when I think about your big hands.”

Katsuki’s control shattered. A raw, ragged sound tore from his throat. His hand, moving on its own, came down to cradle the back of Izuku’s head, fingers tangling in the green curls. Not pushing. Holding. “You fucking… you little…” He had no words. His cock throbbed painfully against Izuku’s cheek.

“Shhh, Daddy,” Izuku whispered, rubbing small, clumsy circles over his clothed pussy, mimicking a child’s ignorant exploration. “I’m just making the bad feelings go away. See? It feels better when I touch it. Does your willy feel better when I rub my face on it?”

“Stop talking,” Katsuki growled, but his hips gave a minute, involuntary thrust upward, seeking pressure. His eyes were black with horror and a hunger so deep it erased everything else. “Just… stop.”

“Make me stop, Daddy.” Izuku’s voice was a breathy, challenging sing-song. He shifted, pulling his shorts and underwear down just enough to expose the neat, curly hair between his thighs. His fingers, glistening now, returned to stroke his own folds. The wet sound was obscenely loud in the silent tent. “Your bad boy is touching his cunny. Aren’t you gonna punish me?”

Katsuki’s other hand shot out, wrapping around Izuku’s wrist and yanking his hand away. “I said stop.”

Izuku whimpered, a genuine, high-pitched sound of need. He was panting, his chest heaving, his small breasts rising and falling rapidly under his shirt. “But it aches, Daddy. It aches so bad. Only you can make it better. You fixed the sink. You check for monsters. Fix this.” He was begging now, the baby talk fracturing into pure, desperate want. “Please. Your hand is so big. Please, Daddy.”

Katsuki stared down at him, at his son’s exposed, trembling body, at the slick evidence of his arousal gleaming in the lamplight. The last thread of his resistance snapped. A low, animal groan rumbled in his chest as his hand, the one not clutching Izuku’s wrist, moved to his own belt.

Izuku’s small hands scrambled for the belt buckle, fingers slipping on the cold metal in his haste. “Let me, Daddy, I can help—”

Katsuki’s larger hand closed over both of his, stilling them. “No.” The word was a low rumble. He pushed Izuku’s hands firmly back into his own lap. “You sit there. You be my good boy and sit still.”

His own movements were deliberate, clinical. The rasp of the belt threading free. The snap of the button. The hiss of the zipper. He shoved his jeans and boxers down just enough to free himself, and his thick, uncut cock sprang out, fully erect and flushed a deep, angry red. It bobbed heavily between them, a stark, obscene contrast to the childlike tableau.

He didn’t guide it with his hand. He used his hips, nudging the broad, slick head against Izuku’s flushed cheek. “Show Daddy,” Katsuki breathed, his stormy eyes pitch black with conflict. “Show Daddy how much you want Daddy’s willy, Izu.”

The old nickname—one he hadn’t used since Izuku was in elementary school—struck the air like a bell. Izuku’s breath hitched, a tiny, wounded sound. His green eyes went impossibly wider, shimmering with tears and want.

He turned his face into the hot, velvety skin, nuzzling like a kitten. He opened his mouth, not to take it in, but to press clumsy, open-mouthed kisses along the shaft. “I want it so much, Daddy,” he whimpered, the baby voice returning, thick with pretend innocence and very real desperation. “Your willy is so big and hot. It used to scare me. Remember?”

Katsuki remembered. Vividly. Bath times, swimming, the boy’s curious, fleeting glances. His stomach churned with acid, even as his cock throbbed against his son’s lips. “You’re not scared now.” It wasn’t a question.

“No, Daddy,” Izuku murmured, licking a slow, wet stripe from root to tip. He tasted salt and musk. His little tongue circled the swollen head, probing at the foreskin. “Now it makes my cunny feel all empty and sad. It needs you to fill it up. Make it better.”

“Your cunny is always sad for me, isn’t it?” Katsuki’s voice was gravel, stripped raw. He cradled Izuku’s head, his thumb stroking the green curls in a grotesque parody of comfort. “Even when you were a little thing. Always dripping for your Daddy.”

“Uh-huh,” Izuku nodded, his nose bumping against Katsuki’s heavy balls. He was panting, his own fingers digging into his thighs. “It’s dripping now. See?” He leaned back, just enough to hook his thumbs into the waistband of his shorts and underwear and shove them down to his knees. The lamplight caught the glisten between his slender thighs, the soft, curly hair dark with moisture. He spread his legs, a shy, exposing gesture. “All wet for you. Just like when I was ten and didn’t know why.”

Katsuki’s control was a thin, cracking sheet of ice. He looked from the exposed, trembling proof of his son’s arousal, back up to the face wearing a mask of youthful guilt. The dissonance should have killed his erection. It made it harder, a painful, aching weight. “You’re a sick little boy,” he whispered, the words layered with horror and a dark, undeniable pride.

“I know, Daddy,” Izuku whined, his hips giving a tiny, involuntary jerk. “Punish me? Please? Make the ache go away.”

Katsuki moved. It wasn’t gentle. He gripped Izuku under the arms and hauled him up, then manhandled him onto his back on the rumpled sleeping bag. He loomed over him, one knee pressing between Izuku’s thighs, forcing them wider. His huge, calloused hand smoothed up Izuku’s flat stomach, over the small, soft breasts, before coming to rest, threatening and warm, on his throat. Not squeezing. Just holding.

“This what you dreamed about?” Katsuki growled, his cock pressing against Izuku’s inner thigh, leaving a wet smear. “Daddy holding you down? Checking for monsters?”

Izuku stared up, transfixed. He nodded, fast and frantic. “Yes, Daddy. Just like that.”

Katsuki lowered his head, his breath hot against Izuku’s ear. His voice dropped to a whisper, a secret for the ten-year-old ghost between them. “The monster’s here, Izu. And Daddy’s gonna fuck it right into you.”

Katsuki didn't wait for an answer. He shifted his hips, the broad, slick head of his cock nudging against Izuku’s soaked entrance. He kept his hand on Izuku’s throat, a warm, inescapable weight. “The monster’s right here, baby boy. You feel him?”

Izuku’s breath hitched, his green eyes wide and unblinking. “I feel him, Daddy,” he whimpered, his voice small and strained. “He’s big.”

“He is.” Katsuki’s own voice was a raw scrape. He pushed forward, just an inch, a brutal, stretching invasion. The tight, clenching heat was obscene. Izuku cried out, a sharp, high sound that was all childlike shock. Katsuki froze, his entire body trembling with the effort. “Shhh. Daddy’s checking. Gotta make sure he’s not hiding in here.”

“He is, he is!” Izuku sobbed, his nails digging into Katsuki’s forearms. His hips tried to jerk away from the overwhelming stretch, but Katsuki’s knee between his thighs held him pinned. “Daddy, it’s too much—”

“It’s just what you need.” Katsuki pressed in another devastating inch, his foreskin rolling back. The wet, resisting slide was loud in the tent. He dropped his forehead to Izuku’s, their noses touching. His stormy eyes were wild, unhinged. “Tell me. Tell me about the dream. The one where I checked under the bed.”

Izuku was panting, tears leaking from the corners of his eyes. “You… you lifted the blanket. To look.”

Katsuki sank deeper, a slow, inexorable conquest. Izuku’s body yielded, desperately wet, sucking him in. “And what did you do?”

“I spread my legs.” The admission was a gasped confession. Izuku’s hands flew to his own mouth, biting his knuckles as Katsuki buried himself to the hilt, their bodies finally flush. A broken moan was punched from his chest. “Oh, God—Daddy—”

“I’m not God.” Katsuki ground his hips, making Izuku feel every thick inch. “I’m the man checking for monsters. And I found one. It’s right inside my little boy’s cunny, all hot and greedy.” He pulled back almost all the way, then thrust back in, hard. The slap of skin was brutal. “Isn’t it?”

“Yes!” Izuku screamed, his back arching off the sleeping bag. The childish cadence shattered into pure, carnal need. “It’s greedy for you, Daddy, it always has been, please—”

Katsuki set a punishing rhythm, each deep drive punctuated by a wet, filthy sound. He fucked him like he was exorcising something, his hand still a loose collar around Izuku’s throat. “Should have checked sooner. Should have known my sweet boy had a monster this deep inside him.”

“You know now,” Izuku choked out, his eyes rolling back. He was clenching around Katsuki with every thrust, his small body jolting. “You’re killing it, Daddy, you’re fucking it out of me—”

“Am I?” Katsuki’s pace turned erratic, his control fraying. He was breathing in harsh, open-mouthed gusts against Izuku’s cheek. “Or am I just feeding it? Giving it exactly what it wants?” He shifted his angle, grinding deep, and Izuku howled, his thighs clamping around Katsuki’s hips. “This what it wanted? Your Daddy’s cock? Since you were ten?”

Izuku could only nod, frantic, sobbing with each thrust. His hands scrabbled at Katsuki’s back, leaving red trails. “Yours, only yours, Daddy, I’m sorry, I’m so sorry—”

“Don’t be sorry.” Katsuki’s voice broke. He was close, the coil in his gut pulled taut. He captured Izuku’s mouth in a savage, biting kiss, swallowing his son’s cries. When he broke away, a string of saliva connected them. “Just take it. Take your Daddy’s monster. Make it yours.”

He pistoned into him, once, twice, three more brutal times, and then he stilled, buried to the root. A guttural, wounded sound tore from his chest as he came, his body seizing, pumping his release deep into the clenching, impossibly tight heat. Izuku felt the hot pulse inside him and shattered, his own orgasm ripping through him squirting, his mouth open in a soundless scream, his body convulsing around the cock that filled him.

Katsuki collapsed on top of him, his full weight driving Izuku into the sleeping bags. They stayed like that, locked together, Katsuki’s face buried in Izuku’s sweaty neck. The only sounds were their ragged, sobbing breaths and the distant chirp of crickets outside the glowing tent.

Slowly, Katsuki softened and slipped out. He rolled onto his side, his back to Izuku, one arm thrown over his eyes. His shoulders were rigid. A long minute passed in the heavy, scent-filled silence.

“Izu.” The name was hollow, drained.

Izuku lay on his back, staring at the amber ceiling of the tent, feeling the warm, sticky trickle between his thighs. “Yeah, Dad?”

Katsuki didn’t turn. His voice was barely audible. “We’re gonna need a bigger tent.”

Katsuki finally turned, his stormy eyes bloodshot in the lantern light. He reached out, his calloused thumb wiping at the tear tracks on Izuku’s freckled cheeks. “We’re doing that again,” he stated, his voice rough but certain. “In the bigger tent we’re buying tomorrow.”

Izuku’s breath hitched, a new kind of wetness springing to his eyes. He scrambled closer, pressing his slender, sticky body against Katsuki’s solid heat, tucking his face into the junction of his father’s neck and shoulder. He inhaled the scent of sweat, sex, and him. “Really, Daddy?”

“Yeah.” Katsuki’s arm came around him, heavy and possessive, his hand splayed across the small of Izuku’s back. He stared at the tent wall, his jaw working. “You broke something in me tonight, kid. Can’t put it back.”

Izuku nuzzled closer, his lips brushing Katsuki’s collarbone. His voice was a sleepy, satiated murmur. “I love you, Daddy.”

The words hung in the hot, thick air. Katsuki’s hand stilled on his back. He closed his eyes, a muscle feathering in his cheek. When he spoke, it was a defeated exhale, a truth he could no longer cage. “I love you too, Izu.” He pressed a hard, dry kiss into the green curls. “Now go the fuck to sleep.”

Izuku smiled against his skin, his body going pliant and heavy. The warm ache between his thighs was a lullaby. He drifted off to the sound of his father’s heartbeat, a frantic, guilty drum against his ear, and the distant, indifferent chorus of the crickets.