The Midoriya kitchen was a battlefield of flour and laughter. Inko hummed as she rolled out sugar cookie dough on the floured counter. Eri, standing on a step-stool beside her, carefully pressed a reindeer-shaped cutter into the soft surface, her silver hair tied back with a festive ribbon. "Auntie Inko, does this look right?"

"Perfect, sweetheart," Inko beamed, wiping her hands on her apron.

At the large farmhouse table, chaos reigned. Shoto and Hitoshi were assembling a gingerbread house with the intense, silent focus of bomb technicians. Denki, leaning against Hitoshi's shoulder, was meticulously applying icing with his tongue poking out in concentration. "Babe, is this structurally sound?" Denki asked, squinting.

"It'll hold," Hitoshi grumbled, but his hand settled gently on Denki's lower back, a silent affirmation.

Izuku stood by the stove, watching the timer on a sheet of gingerbread men. The warmth of the oven kissed his face. He could feel Shoto's calm presence across the room like a anchor. He could also feel the other presence, a constant, burning pressure against the back of his neck. He didn't need to turn to know Katsuki was there, leaning against the doorframe to the living room, a silent spectator.

Eijiro bounded into the kitchen, a bowl of red icing in his hands. "Hey, I found the food coloring! Who wants to make Santa's suit extra vibrant?" His cheerful voice was a stark contrast to the thick, unsaid things hanging in the air. He went straight to Katsuki, nudging him with an elbow. "Lighten up, grumpy. It's cookie day."

Katsuki’s eyes, however, never left Izuku. "Whatever, Shitty Hair," he muttered, but the usual bite was absent. It was low. Private. A rumble meant for one other person to feel, not hear.

"Timer's gonna go off, nerd," Katsuki said, his voice cutting through the chatter. It wasn't loud, but it landed on Izuku's skin like a touch. Izuku flinched, fumbling for the oven mitt. His fingers trembled.

"I know, Uncle Kacchan," Izuku said, the familial title tasting like ash and secret heat on his tongue. He bent to pull the tray out, the movement stretching his sweater. He felt eyes on the curve of his ass, a phantom weight. His stomach clenched. A slick, traitorous heat pulsed low in his belly, immediate and shameful.

Shoto looked up, his heterochromatic gaze soft. "Need help, Izuku?"

"No! No, I've got it," Izuku said, too quickly. He set the hot tray on the stove top with a clatter. The scent of molasses and spice filled the air. Katsuki pushed off the doorframe and walked into the kitchen. He stopped right behind Izuku, not touching, but close enough for Izuku to feel the radiating heat of his body, to smell his cologne and the darker, musky scent beneath.

"Here." Katsuki reached around him, his large, calloused hand covering Izuku's smaller one on the piping bag of white icing Inko had left nearby. It wasn't an offer. It was a demonstration. A claim. He guided Izuku's hand in a short, firm line, icing a smile onto a cooling gingerbread man. "Like that. Don't be sloppy."

Izuku stopped breathing. The rough warmth of Katsuki's palm. The sheer bulk of him at his back. It was a fraction of a second, hidden by their bodies from the rest of the room. Then Katsuki released him and stepped away, taking the piping bag with him. "I'll do the roof. Your hands are shaking."

Izuku just stood there, his hand burning. He caught Shoto's smile from the table—a sweet, unknowing thing. The guilt was a cold knife. The arousal was a flood. He turned his head, just enough. His green eyes met Katsuki's crimson ones across the kitchen island. The look was a live wire. A question. A promise. It said: *The laundry room. In the basement. Ten minutes.*

The laughter from the gingerbread house collapse still echoed. Izuku’s heart hammered against his ribs. This was it. The opening. He forced a bright, apologetic smile, already backing toward the hallway. “I am so, so sorry! I’ll grab the paper towels and a broom from the basement laundry room. It’ll be two seconds!”

“It’s fine, Izuku,” Shoto said, calmly picking a gumdrop off the table. His fingers were sticky with icing. “It was structurally unsound to begin with.”

Hitoshi pinched the bridge of his nose. “Ten points for dramatic failure.”

“No, really, I’ve got it!” Izuku insisted, his voice a chirp that felt too loud in his own ears. He didn’t look at Katsuki. He didn’t need to. He could feel the man’s gaze like a brand between his shoulder blades as he fled the kitchen.

The cheerful noise faded behind him, swallowed by the quiet of the hallway. The door to the basement was just ahead, a dark, narrow mouth. His palms were slick. He paused, listening. Only the hum of the refrigerator and the distant murmur of his family. He reached for the doorknob.

“Izuku.”

Shoto’s voice. Right behind him. Izuku flinched, his hand freezing on the cool metal. He turned, a rehearsed smile plastered on his face. Shoto stood there, his expression soft, a faint smear of red icing on his jaw. He reached out and wiped a speck of flour from Izuku’s cheek with his thumb. “You’re running again.”

“I’m not running,” Izuku breathed, his throat tight. “I’m cleaning. I made a mess.”

“You’ve been jumpy all day.” Shoto’s dual-colored eyes searched his face, not accusing, just concerned. His thumb lingered, stroking the apple of Izuku’s cheek. “Is everything okay? With your family? With… me?”

The guilt was a physical cramp. It twisted deep below the heat, a sickening counterpoint. Izuku leaned into Shoto’s touch, a silent plea for forgiveness. “Everything’s perfect. You’re perfect. I’m just… holiday overwhelmed. You know how my family is.”

Shoto nodded slowly. He leaned in, his breath warm against Izuku’s lips. “I love how your family is. I love you.” He kissed him then, a sweet, chaste press that tasted of sugar and Shoto’s particular, clean scent. It was a kiss of home. Of future plans. Of a ring box hidden in a suitcase upstairs.

Izuku kissed him back, pouring every shred of his fractured self into it. His hand came up to clutch at Shoto’s sweater. He felt like he was screaming inside. When Shoto pulled back, his smile was a gentle, grounding thing. “Hurry back. I’ll defend your honor against the gingerbread tribunal.”

“Two minutes,” Izuku whispered, the promise a lie that choked him.

He watched Shoto walk back to the kitchen light, then he yanked the basement door open and plunged into the dark. He didn’t turn on the overhead bulb. He took the stairs two at a time, the wooden steps creaking under his weight, his heart a frantic drum in the silence. The basement air was cool and smelled of detergent and concrete.

He reached the bottom. The laundry room door was ajar, a sliver of weak light from a utility bulb spilling out. His breath sawed in his lungs. He pushed the door open.

Katsuki was there, leaning against the washing machine, his arms crossed over his broad chest. The dim light carved the severe planes of his face into shadow. He didn’t speak. His crimson eyes tracked Izuku’s every movement, from his heaving chest to the way his hands trembled at his sides.

“You took your time,” Katsuki said, his voice a low gravel in the humid, closed space.

“Shoto,” Izuku gasped, the name both an apology and an accusation. He took a step forward. The distance between them was nothing. Everything.

Katsuki closed the distance in one stride. His hand shot out, fingers tangling in Izuku’s green curls, and he yanked him forward, crushing their mouths together.

The kiss wasn’t just a kiss. It was a claiming. A violent erasure. Katsuki’s tongue plunged into Izuku’s mouth, hot and demanding, tasting, seeking, overwriting the ghost of sugar and Shoto’s clean kiss. Izuku gasped against him, a broken sound swallowed by Katsuki’s hunger. He tasted coffee and fury and something uniquely, devastatingly Katsuki.

“Get his taste out of your mouth,” Katsuki growled against his lips, not letting him breathe. His other hand gripped Izuku’s jaw, holding him still. “Swallow me instead, you traitorous little shit.”

Izuku whimpered, his body going pliant. His hands came up to claw at Katsuki’s shoulders, not to push away, but to hold on. He opened wider, letting Katsuki deepen the kiss, letting himself be consumed. The guilt was still there, a cold stone in his gut, but it was drowned now by a flood of heat, by the rightness of this wrongness.

Finally, Katsuki pulled back, both of them panting. A string of saliva connected their lips for a second before snapping. Izuku’s mouth felt bruised, used. Perfect.

“He kissed you,” Katsuki stated, his voice ragged. His thumb rubbed roughly over Izuku’s swollen bottom lip. “Right before you came down here. I saw.”

“I—I had to,” Izuku breathed, his eyes wide. “He was right there. He’s my—”

“Don’t.” Katsuki’s hand slid from his jaw to his throat, not squeezing, just cradling the pulse hammering against the skin. “Don’t say what he is to you. Not in this room. Not when you're alone with me.”

The distant sound of laughter echoed down the stairwell. The gingerbread house tribunal. A reminder of the world above, ticking away.

“They’re waiting for me,” Izuku whispered, the words trembling.

“Let them wait,” Katsuki murmured, his gaze dropping to Izuku’s mouth. He leaned in again, but this time his kiss was slower, deeper, a filthy, wet slide of tongue that had Izuku’s knees buckling. Katsuki held him up, backing him against the cold metal of the dryer. The hum of the machine vibrated through Izuku’s spine.

“You’re already wet for me, aren’t you, nerd?” Katsuki breathed into his ear, his free hand sliding down Izuku’s stomach, over the wool of his sweater, and past the waistband of his jeans. “Since I put my hand on you upstairs. Since you felt me watching you.”

Izuku cried out when Katsuki’s fingers found his cunt. He was soaked, the fabric of his panties slick and clinging. “Kacchan—”

“Shut up and feel it,” Katsuki ordered, his voice a harsh scrape. He pushed the underwear aside, his thick fingers sliding through the wetness, gathering it, before circling Izuku’s clit. The touch was deliberate, rough, and perfect. Izuku’s head thumped back against the dryer, a choked sob escaping him.

“This is what you ran down here for. This is the mess you really wanted to clean up.” Katsuki worked him with a cruel, knowing rhythm, his eyes locked on Izuku’s crumbling face. “You gonna come for me already? Like a cheap slut?”

“Yes,” Izuku gasped, his hips jerking into the touch. The coil in his belly was winding too fast, too tight. The scent of their arousal mixed with the laundry detergent, a heady, secret perfume. “Please, I’m gonna—”

“No.” Katsuki removed his hand abruptly.

Izuku whined, a desperate, animal sound, his body trembling with denied release. He looked at Katsuki, wrecked and pleading.

Katsuki brought his glistening fingers to his own mouth, never breaking eye contact. He sucked them clean, his tongue swiping slowly over each digit. He groaned, the sound vibrating deep in his chest. “Fuck. You taste like ruin.”

Then he was on his knees. He yanked Izuku’s jeans and underwear down to his thighs in one brutal pull. The cold basement air hit Izuku’s exposed skin, making him shiver, before Katsuki’s hot mouth replaced it.

There was no preamble. No soft licks. Katsuki dove in, his tongue spearing into Izuku’s cunt, lapping at the slickness with a starving, possessive greed. The sound was obscene—wet, sloppy, hungry. Izuku’s hands flew to Katsuki’s spiky hair, gripping hard.

“Oh god—Uncle Kacchan—” The title was a prayer and a curse.

Katsuki growled against him, the vibration sending shockwaves through Izuku’s core. He ate him like a man possessed, like he was trying to devour the very essence of him. One hand clamped on Izuku’s hip, holding him still against the dryer, the other snaking up under his sweater to pinch a puffy nipple.

The dual sensation—the rough pinch, the relentless tongue—shattered Izuku’s last thread of control. The orgasm ripped through him, sudden and catastrophic. He screamed, his back arching, his cunt clenching around Katsuki’s tongue. And he squirted, a hot gush of release flooding Katsuki’s mouth, dripping down his chin, onto the concrete floor.

Katsuki drank it down, swallowing every drop, his own groan of satisfaction muffled against Izuku’s trembling flesh. He didn’t stop until Izuku was sagging, oversensitive and whimpering.

He stood up, wiping his mouth with the back of his hand. His eyes were wild, his cock a blatant, straining outline in his jeans. He looked at the wet spot on the floor, then at Izuku’s ruined, blissed-out face.

“Now,” Katsuki breathed, unbuttoning his own jeans, his voice thick with Izuku’s taste. “You’re clean.”

Katsuki didn’t wait. He didn’t ask. He grabbed Izuku’s hips and pushed forward, his thick, uncut cockhead pressing against Izuku’s soaked, fluttering entrance.

“Uncle—wait, I’m too—” Izuku gasped, his body trying to arch away from the overwhelming sensation.

“You’re not,” Katsuki growled, his voice ragged. He held him firm. “You take all of me. Right now.” He thrust in.

The stretch was brutal, exquisite. Izuku screamed, a raw, torn sound that echoed off the concrete walls. He was so sensitive, every ridge and vein of Katsuki’s cock a lightning strike inside him. He was stretched impossibly full, the ache a bright, white pain that blurred into blinding pleasure.

Katsuki didn’t move. He stayed buried to the hilt, his forehead dropping to Izuku’s shoulder. His breath was a harsh, hot gust against Izuku’s neck. “Fuck. Fuck, you’re tight. Still clenching from your little scream.”

“Kacchan, please,” Izuku sobbed, his fingers scrambling against the dryer. “It’s too much.”

“It’s exactly enough.” Katsuki pulled back, almost all the way out, the drag making Izuku see stars, before slamming back in. The wet, slick sound of their joining was obscenely loud. “This is what you are now. My fucked-out little secret.”

He set a punishing pace from the start, each thrust jolting Izuku against the humming machine. There was no gentle build, only claiming. Katsuki’s hands gripped his ass, fingers digging into the soft flesh, spreading him wider, taking him deeper.

“You feel that?” Katsuki grunted, his own control fraying. “That’s me. In your boyfriend’s place. Ruining you for him.”

Izuku could only nod, tears streaming down his freckled cheeks. His clit, trapped between their bodies, throbbing helplessly with each brutal drive. The coil was winding again, impossibly fast, a second orgasm building on the wreckage of the first.

“Gonna come again?” Katsuki rasped, his rhythm growing erratic. “Gonna squirt all over my cock while I fill you up?”

“Yes—yes, Uncle Kacchan, I’m gonna—”

The confession broke him. Izuku shattered, his cunt milking Katsuki’s length in frantic, pulsing waves. He squirted again, a hot rush that slicked their thighs and dripped to the floor with a patter. The force of it pushed Katsuki over the edge.

With a choked, guttural roar, Katsuki buried himself deep and cummed. Izuku felt the hot pulse of his release, filling him, a claiming that went past skin. Katsuki shuddered through it, his whole body rigid against Izuku’s.

For a long minute, the only sounds were their ragged breaths and the distant, cheerful melody of a Christmas song from upstairs. Reality seeped back in, cold and sharp.

Katsuki pulled out slowly. Izuku whimpered at the loss, the sudden emptiness, the feel of come leaking down his thigh. Katsuki tucked himself away, his movements precise, his face a mask of stormy satisfaction.

Katsuki looked at the panties, a damp, crumpled heap on the floor. He stooped, picked them up with two fingers, and without a word, brought the soft lace to Izuku’s trembling thighs. He wiped carefully, cleaning the mess of slick and cum that leaked from Izuku’s pussy, his touch surprisingly methodical. He folded the soiled fabric, a dark patch in the center, and tucked it into the back pocket of his jeans. “For later,” he said, a low smirk tugging at his mouth.

He stepped back into Izuku’s space. His hand came up, cupping Izuku’s jaw, his thumb stroking over a freckled cheekbone. The gesture was shockingly tender after the violence of his possession.

“Look at me, nerd.”

Izuku’s eyes, glassy and wet, lifted to his. Katsuki leaned in and kissed him. It wasn’t a claiming this time. It was slow, deep, a thorough exploration. His tongue traced the seam of Izuku’s lips, and Izuku opened for him with a broken sigh, his hands coming up to clutch at Katsuki’s shoulders.

They stayed like that for a long minute, mouths moving in a desperate, searching rhythm. The taste of Izuku was still on Katsuki’s tongue, a shared secret. When they finally broke apart, both were breathing hard.

“You’re a fucking disaster,” Katsuki murmured, his forehead resting against Izuku’s.

“You made me one.”

“You were already mine.” Katsuki pulled back, his crimson eyes scanning Izuku’s wrecked face, his swollen lips, the sweater askew. “Get your shit together. Pull your pants up.”

Izuku’s hands shook as he fumbled with his jeans, wincing as the denim rubbed against his oversensitive flesh. He could still feel the phantom stretch, the ache of being filled. He felt hollowed out and stuffed full, all at once.

Katsuki watched him, already composed, his own jeans buttoned, the only evidence a faint damp spot near his fly. “You got five minutes. Then you get your ass upstairs and smile for your fucking prince.”

“Don’t call him that,” Izuku whispered, zipping his fly.

“Why? It’s what he is, isn’t he?” Katsuki’s voice was a cold blade. “The one you’re gonna marry. The one you go home to after I’ve fucked you stupid in a basement.”

Izuku flinched. “Stop it.”

“Make me.” Katsuki stepped close again, his presence a physical heat. “Go on. Tell me you don’t want this. Tell me you’re not already thinking about when I’m gonna use those panties by myself later.”

Izuku said nothing. His silence was the loudest confession.

A cruel satisfaction flashed in Katsuki’s eyes. He turned and headed for the stairs. “Five minutes,” he repeated, not looking back.

Izuku stood alone in the humming, scent-filled dark. He could hear the faint, happy sounds of his family above. The squeal of Eri’s laughter. Denki’s bright chatter. Shoto’s low, calm murmur. A world of light, and he was trapped in the dark, his body humming with a secret poison. He leaned his forehead against the cold metal of the dryer, and waited for the trembling to stop.