To Deku, Kacchan had never seemed like a patient person.

He knew what he wanted and waited for nothing and no one on his way to his goal.

But the new hunger Deku found in those scarlet eyes told a different story.

His gaze screamed finally, as if this was the very moment he'd lived for.

Being on the receiving end of that look made it hard to breathe.

Those eyes reflected more than simple triumph.

This was a predator stalking prey. Plunder, lay siege, and leave none alive.

Deku's heart quickened, thundering through his chest then watched Kacchan's perfect tongue lick at his lower lip. His circling finger became more insistent, pushing and prodding for entry but Deku was dry.

Kacchan sucked his teeth, looking almost displeased, pulling a small whine from Deku.

"Get yourself ready, Deku."

The dog stared at him, blinking in confusion, which was apparently the wrong move because Kacchan grabbed Deku's muzzle roughly, pulled it down between fluffy legs, and nestled his wet nose between his new pair of dog balls.

"Did I stutter, Deku, or is your stupid dog brain already winning? I said. Get. Yourself. Ready."

Kacchan's eyes flashed dangerously and he let go, waiting for Deku's next move.

Deku kept his nose where the blond had shoved it, then shyly licked over one of his balls. His toes curled at the feeling though they weren't as sensitive as they'd been when he was human.

He focused on them for a short while, then his tongue somehow ended up coaxing his cock from his sheath. It tasted bitter, and yet the feeling of his own tongue wrapping around himself was glorious.

He bucked into his own face whimpering as something new and rabid and desperate churned in his gut but then there was a hand digging into the back of his neck.

The hand pulled him up like one might a kitten, but Deku's body was too heavy for this position. It put too much strain on his neck and spine…

Then he was falling, dropped to the floor and fumbled the landing and Katsuki followed him down.

"Shoulda fuckin' known," Katsuki grunted, keeping Deku pinned under him. "Gave you a simple job, and just like with everything else, you fucking fail."

Deku flinched at his words, tail tucking tight between his legs but Katsuki caught it and wrenched it aside. "I gave you a chance to make this easier."

Katsuki was reaching for the waist of his jeans, the button and zipper already handled. "But this isn't about you, Stupid Deku."

Slowly.

Deliberately.

Katsuki eased them down until his erection bobbed free of its prison.

Instinctually, Deku wanted it in his mouth, the sight of it enough to make him drool.

Katsuki fisted his cock and sneered, "ass up, Deku."

Deku obeyed, his own dick hanging angry and ignored between his legs. Everything in him screamed to mount. To fuck. To mark. But Katsuki was prodding at his hole again.

Something wet and hot landed on his hole and he looked back to see Katsuki whipping his chin.

He didn't have time for much else before a finger was being pressed inside him. It wiggled past his rim and Katsuki groaned as if fluttered and clenched around him.

"Oh fuck…" he breathed and pushed further, feeling Deku's soft walls. He stared at it, tiny pink and already straining as he pressed in the rest of the way.

Deku whined softly, eyes screwed shut.

This didn't feel like he imagined it would.

Quite frankly it hurt even with Kacchan's spit dripping from his hole.

"You don't know how I've waited for this, Deku." Katsuki purred, yanking his tail further up his back. "I've wanted to fuck you like this since middleschool."

WHAT?

Deku tried to look back, to make eye contact but Katsuki loomed over him, pinning him to the floor by his neck at the base of his skull.

"This is all you've been alive for. The culmination of your entire existence. Everything has led to this."

Deku couldn't silence the intrusive thoughts that swirled inside his head, but then, Katsuki's finger was sliding out. It pulled free, then there were two, pressing in, scissoring him open. They were careless, single minded in their pursuit.

Katsuki was breathing hard, the importance of this moment feeling almost too much.

He spat again at Deku's hole sending a shiver through him and he keened low, clawing at the floor below him.

Being spread open on Katsuki's capable fingers soon had Deku drooling. His muscles protested the motions, fighting Katsuki's advances and attempts to move deeper, but he pushed past them.

Deku's body would learn to take him, with or without the scarring to prove it and ,with the way Deku was whining at the two measly fingers in his ass, scars wouldn't be surprising.

Katsuki smirked at the mess Deku had become, his eyes hazy and unfocused. "Almost there, boy," he cooed and began to force in a third finger.

Deku's eyes snapped wide and his yelp almost made Katsuki feel something beyond excitement, but this was his moment. Deku's body would bend to his will.

"Cant wait- I-" Katsuki began and his fingers pulled from inside his mutt. He wiped them in Deku's fur then gripped his cock and lined it up with Deku's entrence.

Deku keened as it pressed against his hole, eyes blown so wide the whites were showing. It was too big! Too big! There was no way- and yet Katsuki kept pushing.

Deku was struggling now, paws scrabbling against the floor but Katsuki didn't stop.

With his thumb he pried Deku's hole open just enough to allow his tip slip inside with a 'pop'.

It stole the air from Deku's lungs but a thrill he couldn't explain ripped through him.

Katsuki groaned, continuing to feed himself into the impossibly tight hole. "Fuck, Deku," he breathed, using Deku's tail to pull the beast toward him. After a series of shallow thrusts, he was seated fully in Deku's ass.

"Finally…" it was almost a laugh, almost a growl. The sounds coming from Katsuki's throat were possessive, bordering on feral. "Fell that Deku?"

Katsuki pulled out slightly then thrust back in, pulling a whimper from Deku as he repeated the gesture ever so slowly.

"Fuck yes. Deku. This is what you were meant for. 'S fucking incredible."

That tiny bit of praise shot a blinding wave of pleasure through Deku's body and he bucked back against Katsuki, pushing him deeper into his heat.

Katsuki's fingers petted through his fur then settled at his hips. "Good boy, Deku. Good boy," Katsuki murmured.

Deku's tongue lulled from his mouth, eyes rolling back into his skull as Katsuki rearranged his organs. "Gonna ~fuck~ gonna fill you up, Deku."

If Deku had been able to speak, he would have begged for it. His entire being was on fire. He wanted to cum, he wanted to be filled, he wanted to be Katsuki's. His entire world narrowed, drawing the movement inside him into sharp focus.

He was aware he was whimpering, begging in the only way he could as Katsuki's pace grew erratic.

'Its happening,' Katsuki thought, that thought alone pushing him closer to the edge. This was it. And it felt so fucking good… His fucking Deku whined for him, lost in his own pleasure and Katsuki moaned as his release ripped from him.

He slammed into Deku fucking himself through his orgasm, deturmined to leave every drop of his cum DEEP inside Deku.

Katsuki shook with the intensity of it, his legs felt like jelly. This moment didn't feel real but it was.

Deku humped the ground below him, yet to find his release and Katsuki grinned. "Awe. What's wrong Deku?" He pushed in again, thrusting teasingly in small circles. "Not full enough yet?"

With a wicked sneer, Katsuki grabbed Deku's hips and brought them to his own, pushing in as far as he could.

Deku froze as something hot poured into him, pumping him full until he was squirming and still it didn't stop. "Feel that Deku? You're fuckin mine. Pumped full of my cum and marked as my bitch."

Without pulling out of Deku's spent hole, Katsuki reached into his pocket and pulled out a stainless steel plug, fitted with a glittering green stone that matched Deku's eyes.

"Can't have you spilling everything I just gave you." He rubbed a hand over Deku's distended belly. It was tight under his fingers and he intended to keep it that way.