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Kirishima watched as Katsuki toddled across the living room with a couch cushion pinched in his fangs, amused at the sight. Blond furry ears flicked in the spiky locks Katsuki called his “hair” (not fur, apparently) and the snarly cat-hybrid pretended not to notice Kirishima’s smirking expression.
“Pspspspsps,” Kirishima teased and the deep engine growl emitting from Katsuki’s throat was adorably fearsome.
Katsuki remerged from his room without the pillow, hair noticeably mussed and one ear flipped inside out.
“Here, kitty kitty,” Kirishima cooed, holding his hands out although he didn’t approach. “Let me fix that for you.”
The glare Katsuki shot at him would be menacing if Kirishima hadn’t gotten used to it in the past two years and he grinned when Katsuki sidestepped his outstretched arms to pick up more pillows, one under each arm and another pinched between his teeth. He brought these into his room as well.
Kirishima laughed. Katsuki’s cat-like behaviours never failed to delight Kirishima when he got close to his heat.
2 years ago, Kirishima adopted Katsuki as a cat-hybrid companion. The blond was skittish, growly, hissed at everything that moved—and Kirishima fell in love with him at first sight. So he brought him home. He hadn’t expected Katsuki to take over the household so quickly and he certainly hadn’t expected Katsuki to behave so human-like once he was in Kirishima’s apartment but goddamn did Katsuki acclimate with the speed of a bullet train when he began to take care of their home.
(Katsuki claimed it was because he saw himself as the overlord of the house but Kirishima was pretty sure it was because Katsuki wasn’t afraid of being returned anymore.)
Most hybrids retained their animalistic habits, but Katsuki in his everyday life never so much as swiped a glass off the counter (Kirishima was certain he had spilled more cups in his lifetime than his cat hybrid) and he only hissed at the dogs during his window “patrols” and activated his predator instincts during play time—Katsuki was very good at hunting. The only exception, of course, was during his heats. Then he was a very cat-like cat.
Kirishima observed Katsuki not-so-discreetly rub his ass on the corner of the coffee table and knock a few snack tubes onto the floor. He dove for the treats and attempted to rip them open with his paws and teeth and yup, he was definitely in preheat, maybe even on the cusp of actual heat.
“Here Katsuki!” Kirishima implored and Katsuki snapped to attention with dilated eyes and a snack tube hanging from his mouth. “I’ll open those for you.”
As Kirishima steadily squeezed out the treat paste for Katsuki to lap at—“hey,” Kirishima warned when Katsuki got too excited and almost bit a hole in his thumb—he reflected on the typical cat behaviours from Katsuki. He’d already knocked four cups off of tables and counters, suffocated Kirishima in his sleep by sitting on his head, and screamed the song of his (very very loud) people when Kirishima tried to take a shit in these last 24 hours.
But, Kirishima thought as he dodged another attempt at hand amputation from Katsuki’s teeth, he found it all worth it because it was during this time that Katsuki looovved being pampered and Kirishima got to do all the pampering. Pets, brushes, and cuddles were currently at an all-time high in the Kirishima household and he could not be happier—both of them actually, Katsuki’s purr was like a mini engine, and Kirishima had to restrain himself from squealing every instance. Plus, when Katsuki went fully into his heat, he always took the shark plushie Kirishima gifted him into his soundproof locked room to ride out his heat; Kirishima’s heart could not burst anymore from happiness if he tried.
So yes, Kirishima was happy, Katsuki was horny, and the human-hybrid duo coexisted very peacefully during his heat cycles.
Although, Kirishima noted, as Katsuki stole the shirt he literally had been wearing 2 seconds ago, Katsuki seemed to have picked up another trait.
Clingy.
Katsuki dashed back to his room and reappeared wearing the shirt he had just stolen. The big t-shirt hung loosely on his smaller frame and—Kirishima was reminded when Katsuki lifted his tail—he was butt-ass naked everywhere else. That was new too.
“Do you need anything?” Kirishima tried again. “Your shorts maybe?”
Katsuki owned a pair of shorts with block-printed words: “In Heat. Do Not Pet.” on them. They were a gag gift from one of Kirishima’s friends and Kirishima wasn’t sure if Katsuki actually knew how to read because he never complained about the messaging. Of course, Kirishima always petted Katsuki during his heat—right above his tail and butt with the printed shorts.
“Rrrr rrrrr.”
Katsuki made a growly noise deep in his throat and Kirishima could tell that he was frustrated with something. He didn’t move, however, Katsuki had a penchant for solving his own problems and hated getting help—the cons of an independent cat, Kirishima supposed.
“Rrrrrr.”
With a final grr, Katsuki crossed the living room to where Kirishima sat and plopped down on the seat cushion next to him, raising his tail high in the air.
“You want me to pat your butt?”
Katsuki stared at him with big doe eyes and Kirishima took that as a yes.
Kirishima’s firm but gentle pats at the bottom of Katsuki’s back had the kitty mewing with every pet. Pleased, he arched his back and snuggled closer to Kirishima’s lap until he was practically drooling on it. Kirishima swallowed and defiantly looked away when he saw Katsuki’s hips lift higher and the sway of fuzzy balls came into view. Oh god, he hoped his boner wouldn’t make an appearance because there was no way Katsuki wouldn’t notice since he was staring right at it.
Kirishima cleared his throat and continued patting. “Good boy, good boy,” he praised and Katsuki’s head bumped against his bare chest, nuzzling against his pecs. “Good boy.”
Once Katsuki started to get antsy, Kirishima slowed down. He knew that the cat-hybrid was more easily overstimulated in his heat and was probably about to—
“Ow!” Kirishima exclaimed when Katsuki’s jaws closed around his hand. Yeah, he probably deserved that. “Sorry, Katsuki.” He removed his hands and instead smoothed back Katsuki’s ears, smiling as the blond raised his chin and let him rub against his scent glands. “Is that better?”
Katsuki’s purr was a resounding yes and his biscuit kneading was a true sign of his happiness, although his occasional claws in Kirishima’s thighs had Kirishima tensing beneath him.
Soon, Katsuki’s eyelids drooped and his head bobbed up and down, trying to stay awake. Kirishima resisted letting out a coo in case he interrupted Katsuki’s sleeping bug, but within a matter of seconds, Katsuki’s head dropped onto Kirishima’s lap and then he was asleep.
Kirishima bit his lip, smiling. He took two dozen photos on his phone before gathering up the kitty and carrying him to his room. He didn’t have to worry about waking the other up as he had done this a thousand times, but regardless, he was slow and careful in his steps, making sure he didn’t accidentally knock the other on any chairs or doorframes.
Once he got to Katsuki’s room, however, he frowned. Katsuki’s room was stripped bare. Save for his bedsheets, his blanket, pillow, and even shark plush was gone, leaving an empty slate with no owner. That was very strange. Katsuki always stayed in his room for his heat, but this room was unacceptable for any heat-afflicted hybrid!
Then Kirishima saw a sock. And then another sock. Then a shirt on the floor that led further down the hall. He followed the trail of discarded clothing—some his, some Katsuki’s—and stepped into his own room.
Oh. So this is where Katsuki wanted to spend his heat.
Kirishima wasn’t about to complain. If Katsuki wanted to ride out his heat in Kirishima’s room, he would be happy to give it up for a week. He could stay on the couch or even in Katsuki’s room to accommodate his hybrid companion. Plus, this was his first time seeing Katsuki’s nest.
As Kirishima gently eased Katsuki into the dip of his nest, he marvelled at the work of art Katsuki had constructed. The nest took up the entirety of Kirishima’s bed, a tall wall of fabrics sat against the wall corner, and Katsuki had laid half of the foundation with a cool gel mat and the other with a heating pad—perfect for the fluctuating temperatures he would undergo in his heat. Kirishima preened. His kitty was so smart!
He placed Katsuki on the heating pad since he wasn’t burning up yet and the cat-hybrid’s purrs amped up when he snuggled onto the warm surface. Kirishima smiled and rubbed his cheek lightly once more before leaving.
But a tug at his pants stopped him.
Kirishima glanced back, but Katsuki didn’t say a word, still holding onto his shorts between pinched fingers. When Kirishima questioned him with a raise of his eyebrow, the hybrid only let out a tiny “mew”, eyes hooded as deep slits stared back at him.
“Kitty?” Kirishima broached.
Katsuki fidgeted at the nickname, but eventually, he breathed out a single word, so quiet Kirishima would’ve missed it if he wasn’t so transfixed by Katsuki’s expression.
“Stay.”
Heart trembling in his ribcage, Kirishima leaned in and when Katsuki didn’t protest, he carefully laid down next to his kitty. Immediately, the cat-hybrid darted into his chest, huffing when Kirishima, still in shock, didn’t hold him until Katsuki tugged at his arm. Kirishima embraced Katsuki easily, however, and he gave a small smile.
“It’s the perfect nest,” he praised and Katsuki’s rumbles against his chest grew louder.
“I know,” Katsuki said haughtily and… did Kirishima hear a hint of shyness? “I made it for my mate.”
Kirishima’s mouth dropped into an O. He wasn’t stupid. He knew exactly what Katsuki meant. Kirishima’s stolen clothes, Katsuki’s nest in his room, the leg that just slipped between Kirishima’s own. Katsuki wanted him as his mate. And the answer was simple: Kirishima would never deny him; he had been wishing that their relationship could rise beyond the simple human-companion bond they had now too.
He kissed the crown of Katsuki’s hair before drawing the hybrid’s face up—oh, his little sweet face was blushing with hope and nervousness—and molding his lips to Katsuki’s as an answer.
“Mew.”
Katsuki melted, oh, he melted so readily and Kirishima had to swoop down to capture his lips more firmly, grinning when Katsuki’s slightly rough tongue licked into his mouth. He licked back.
“I’m gonna take care of you, baby” Kirishima declared when they parted briefly. “I love you so much. I’m going to take care of you so good.” Then he dove for Katsuki’s sensitive neck, laving his tongue everywhere he could as the hybrid meowed underneath him in delight.
“Pl-please, please!” Katsuki panted. “Mate! Ei! Mate!”
Kirishima didn’t want to wait, but he couldn’t tear himself away from the expanse of Katsuki’s collarbones, worshipping the skin there before moving to the new canvas revealed to him underneath Katsuki’s chin when the kitty tipped his head back
“Eijirou!”
Katsuki’s baby claws caught in Kirishima’s back, pinpricks of his trimmed nails sending shivers down Kirishima’s spine and he shuddered when the contrast of Katsuki’s paw pads and claws had him moaning against the hickey he was creating.
“Kitty,” Kirishima gasped and then his lips were smashed against Katsuki’s again when Katsuki’s paws cupped his face. “Oh Katsuki, you’re the best thing that’s ever happened to me.”
Katsuki’s eyes glazed over, heat-addled brain settling in and Kirishima could visibly see his pupils enlarge and his ears shoot straight up. He knew that Katsuki’s heat would soon impede his speech and heighten his urges as it did every time.
As if right on cue, Katsuki let loose one of his signature indications of heat. He didn’t howl, but his warbling cry was loud and echoed in the room, calling for relief that his body ached for.
“I gotchu, baby. Be patient for me, okay?” Kirishima reassured.
He pushed himself off the bed, dodging Katsuki’s attempts to seize him and hastily threw off his pants. His underwear was the next to go and when Katsuki saw his bare dick, he went into a frenzy.
“Cock!” Katsuki cried out and he heedlessly flipped himself over on the bed, shaking his ass in the air as his back drew into a deep arch and he smothered his face into Kirishima’s pillow. His muffled yowl was pitiful and needy.
“Oh my god, shit Katsuki.”
Kirishima’s shirt on Katsuki’s body fell towards his chest and Kirishima could see his sleek skin and fuzzy happy trail lead down to his weeping cock and hole. His rump was blushing pink and his rim practically winked at him as Katsuki’s tail flicked up and down impatiently, hitting him in the face with soft fluff several times before enticing Kirishima again with sensual waves.
Kirishima huffed out a breath in amusement and stilled Katsuki’s tail at its base with an enclosed fist. He soothed his kitty with a single stroke upwards to his tail’s end and held it away, assuring Katsuki’s whines before dropping his mouth open and laving a wide tongue right over Katsuki’s ass.
Katsuki squealed in delight as Kirishima licked him from balls to hole, eagerly chanting for more as his hips shoved back excitedly. Kirishima grunted as he was practically smothered by Katsuki’s thick cheeks and he stabilized Katsuki’s hips as a remedy, holding him in place as he ate out Katsuki’s hole. Rivets of slick and spit ran down his kitty’s thighs and mewls of need echoed longingly through the room.
“Ei, Ei, Ei,” Katsuki gasped. “Inside! Inside!”
Kirishima stuck his tongue fully into Katsuki’s ass, as deep as he could and swirled the muscle around, mapping out every inch of Katsuki’s entrance. Katsuki’s body spasmed in response and he howled as he desperately rutted against Kirishima’s face.
“No! No!” Katsuki cried, tears dropping from his eyes. “Cock! Cock only!”
Kirishima pulled back, panting as he took in Katsuki’s words. The cat hybrid writhed under his hands, whining for Kirishima’s touch again and really, it shouldn’t surprise Kirishima that his spoiled bratty kitten was a spoiled bratty kitty in bed too.
“Fuck,” he swore. His mouth was dripping and he licked the wet away as he yanked out his cock and stroked it to fullness. There was no time to prep him—and no way Katsuki would wait for his fingers—so he slapped his cock right over Katsuki’s crack and smeared the head of his dick over Katsuki’s entrance.
“Now!”
Kirishima’s cock glanced off of Katsuki’s small hole a few times before Kirishima pried Katsuki’s asscheeks wider and pushed in in into Katsuki’s startling warm and pliant inside. Katsuki yowled and Kirishima squeezed Katsuki’s tail to brace himself for the sheer pleasure that enveloped his cock, bringing another bout of Kirishima’s groans.
Katsuki’s back was arched in such a deep curve, Kirishima was afraid he would be aching, but nothing seemed to matter to Katsuki other than the fact that Kirishima wasn’t moving.
“More! More! More!” Katsuki howled like the dramatic cat he was and Kirishima doubled over when Katsuki’s walls clamped down too tight on his dick.
“Shit, shit. Bear with me darling, okay?” He had already pushed several inches into Katsuki’s ass, but there was still a good portion of his dick left and Katsuki was too wound up to push in any further.
Kirishima reached over to his nightstand, eliciting protests as he had to stretch to the wide. He reassured Katsuki with gentle pets before grabbing a bottle of lube to drench his fingers in.
“RRRRRRR.”
“I know, I know,” Kirishima soothed as Katsuki growled angrily at the feeling of him pulling out. “I promise I’ll make it so good, okay?”
He was quick to flip the cat hybrid onto his back, batting off swinging paws and the sound of indignant growling as Katsuki grew annoyed at the fact that Kirishima wasn’t fucking him. He stretched Katsuki’s hole to the best of his abilities, holding down a squirming kitty the same way he had to hold Katsuki down to take his medicine, and when Katsuki finally had enough (those bunny kicks were not to trifle with!), Kirishima placed back the lube. Only to pause when his hand touched an item he hadn’t put there.
He pulled out the donut-shaped silicone object and inspected it with confusion.
“Katsuki?” He asked. “What is this?”
Katsuki caught sight of the red toy and for the first time in his heat, he stilled. He bit his lip and had the shame to look away. “Knot,” he said in a small voice.
Knot. Knot.
Oh my god, Katsuki wanted Kirishima to knot him! Kirishima stared down at his cat in bewilderment. He hadn’t anticipated Katsuki to have a knot toy of all things, but when he thought about it, it started to make sense.
He smiled teasingly at the other. “So you do like puppies, kitty cat.”
The affronted look Katsuki gave him spurned a laugh out of Kirishima and he slipped the knot ring on, noting how snugly it fit over the base of his cock.
“Okay, let’s try this again, shall we?”
This time, Kirishima sank in all the way—minus the knot—and the way Katsuki’s expression scrunched, overwhelmed by the inches he was suddenly taking was worth every hiss. Kirishima gave a few test thrusts to get used to the feel and Katsuki enthusiastically canted his hips back at him, sending a puff of breath to exhale from Kirishima’s parted lips.
Fuck. It was so good. Katsuki was so good. He was molten gold on the inside, all goopy and messy as he cradled Kirishima’s dick and made him feel like he was sliding into home.
“Katsuki,” Kirishima moaned earnestly. “I love you, I love you so much.”
The shine in Katsuki’s eyes had Kirishima cooing and he wiped those stray tears away before falling into Katsuki’s embrace, capturing his lips in a kiss he channelled all his warmth into. He rocked their bodies together, pushing in and out of Katsuki little by little, coaxing a gentle pace to proceed.
Katsuki loved it. His purr was so loud in Kirishima’s ears and he was nibbling at Kirishima’s lobes from the sensation. He let Kirishima pour his love into him and he eagerly reciprocated, mewing little “love you, love you!” into the air. Kirishima almost lost his composure, but the way Katsuki held him close to his heart gave him the strength to keep going and he knew he had to make this first part of the heat special. One that was only for them before Katsuki’s mind drifted further into the fire blazing through his body.
He gave Katsuki one more deep kiss, cupping the other’s face close to his and repeated his blessed words. “I love you so much, Katsuki.”
Katsuki tossed his head to the side in bliss, barely able to get out the returning words. God, he was so needy now.
“Good?” Kirishima asked, nuzzling the side of his kitty’s cheek.
With a burst of energy, Katsuki suddenly bit him squarely on the neck, eliciting a yelp from Kirishima. It didn’t hurt, but Kirishima could feel Katsuki dragging his canine teeth over the sensitive skin and he moaned, clutching the back of Katsuki’s head.
“Katsuki?” Oh, his voice was shaky.
Katsuki broke off, his flushed face and red eyes never losing focus. “Mark!” He demanded and bit Kirishima again.
“Ah!” This time, Katsuki got him in the ear. He winced. Right, right. Katsuki’s cat instincts must be wanting to be claimed right now. He wanted love, he wanted to be cherished, he wanted to belong to Kirishima. And it was a good thing Kirishima had no intention of ever letting him doubt he was anything else.
With a mouth full of sharp teeth, Kirishima turned Katsuki’s face to the side and bit his nape, refusing to hold back as his own mark throbbed. Katsuki immediately cried out at being scruffed and his head hung limply in Kirishima’s hold, whimpering at the sharp score of Kirishima’s fangs as he marked up Katsuki’s scent gland.
“Mate!” Katsuki wailed and Kirishima could feel his wet insides pulsing around his cock, true evidence of how much Katsuki liked it.
Kirishima growled and began to fuck into the blond, refusing to let go especially when Katsuki’s paws clung to his neck desperately and the little noises that ebbed out of his chest contended with the toe beans squishing against Kirishima’s skin. His knees wrapped around Kirishima’s waist tightly and Kirishima couldn’t imagine existing anywhere else than here; the urge that shone in Katsuki’s eyes and the desire that bloomed in his heart fuelled his growing rapid pace and soon, he was thrusting his hips quickly into Katsuki’s squelching hole, churning up a sticky froth between their bodies.
Katsuki’s breath hitched and he mewled at the increasing intense pleasure, pinpricks of his claws digging into Kirishima’s back until Kirishima pried them off and intertwined their hands against the sheets. He began to pound Katsuki into the mattress, focusing on the places that had Katsuki keening and when Katsuki’s tail looped around his thigh, wordlessly demanding he go faster, Kirishima obeyed.
Bed creaking and the nest shaking from their efforts, the air between them stifled and Kirishima could hear Katsuki’s cries right in his ear as he begged for more.
“Close!” Katsuki warned and Kirishima swore under his breath, letting go of Katsuki’s nape.
“Together,” he promised and that seemed to set something off in Katsuki’s instincts.
Katsuki enthusiastically marked Kirishima, dragging his fangs along the expanse of Kirishima’s neck, collarbones, and chest and Kirishima too laid more “claims” wherever he could reach on Katsuki. Their sweaty bodies blossomed with deep reds and purples as they carved their love into each other and gripped marks into skin so that the other would never forget who made them when they were parted.
Kirishima’s hips stuttered when Katsuki latched onto his nipple and left behind a dark bite mark on his pec, petting the hybrid’s cat ears with one hand and purposely rubbing the base of them to draw out a heady purr from Katsuki. Soon, Kirishima had a limp kitty in his grasp and he grinned as he continued to bite and suck hickeys across Katsuki’s tits, noting how the blond shivered and enjoyed all the little bursts of pleasure littering across his skin.
He gave another full thrust and he must’ve struck Katsuki’s prostate because the hybrid gasped and tightened his legs around Kirishima’s waist, shoving him in deeper.
“Ei! Knot! Knot!” Katsuki pleaded and Kirishima groaned as he did his best, the knot ring bumping steadily against his opening slippery hole. “Ei!”
“Fuck!”
Kirishima let go of Katsuki’s paws and folded him in half, mindful of Katsuki’s squeaks before plunging his cock back into his hole.
“You want my knot, baby?” Kirishima panted. “Want me to fill you up?”
Katsuki squealed and Kirishima groaned as Katsuki wrapped his arms around him again, this time only paw pads squishing into his shoulders.
“Breed!” Katsuki chanted. “Breed!”
“Haah, I’m gonna make you so full of my cum, baby. Gonna breed you ‘till you’re spilling. Gonna make you take it ‘till you’re screaming.” Kirishima growled, yanking on Katsuki’s tail which had him arching and sent into another frenzy as he tried to touch Kirishima everywhere.
“Breed!” Katsuki begged, limbs locked around Kirishima’s body as he tried to make them into one being. “Put—put your kits! In me! Kits! Ei, I wan—I want kits! Please!”
“Oh, fuck.”
Kirishima lost his mind. He fucked the entire length of his cock along with the artificial knot into Katsuki’s ass in one fell swoop and his mind burned with the image of golden red-eyed kits lying on Katsuki’s belly as they each suckled on one of Katsuki’s eight nipples.
He spilled, heavy and thick, into Katsuki’s waiting womb and the hybrid let out a high-pitch whine as he too splattered all over his belly. Both of them were heaving as they came down from their high and Kirishima tried to brace himself over Katsuki’s body so as not to crush him but the cat hybrid only chuffed in response, yanking him down until they were finally pressed skin-to-skin.
“I love you, I love you,” Kirishima peppered kisses all over Katsuki’s face. “Fuck, that was so good, kitty.”
“Love,” Katsuki yawned, “you,” he murmured and Kirishima smiled at Katsuki’s spoken love for him.
Their bodies were covered in hickeys and bite marks, the proof of their coupling, and Kirishima wanted nothing more than to trace over them again with his tongue. However, Katsuki was quick to claim his lips and he licked all over his teeth as Kirishima laughed. He embraced Katsuki and gently rolled them over so that he was on the bottom as Katsuki laid across his body. The knot was still safely kept inside Katsuki’s ass and he didn’t seem like he wanted Kirishima’s cock to leave any time soon so Kirishima just let it be. He was confident that Katsuki would want morning sex anyways—his heat wasn’t over.
Katsuki nipped at his chin and he soothed his kitty with pets and sweet words. The hybrid seemed to have gained an obsession with his stubble as he rubbed and licked at Kirishima’s jawline and Kirishima could tell that the action calmed Katsuki down. He nuzzled back a few times and by the time he was stroking a path down Katsuki’s back to the tip of his tail, the hybrid had dozed off on Kirishima’s chest.
A rhythmic purr slowly grew louder in Katsuki’s chest and Kirishima could feel its deep vibration through his body. He poked Katsuki’s tongue blep back into his mouth like had done so many times before and smiled warmly at the serene expression on Katsuki’s visage.
This was everything he ever wanted; this was what he had been wishing for; this was his life now; and it was perfect.
Within moments, his eyes were drooping from the lull of Katsuki’s inner lullaby and just before he fell asleep, he laid a protective hand on Katsuki’s back, ensuring his kitty would be kept close.
“I love you, Katsuki,” he whispered one more time into his kitty’s fluffy ear, chuckling when it twitched, “you’ll always be my one and only.”
“Mew.”