Squeezing into tight spaces [NSFW]

I'm using bold today instead of italics because this is important!! This fic features Dubcon, Somnophilia, and Kacchan being kind of a jerk at times. Please do not read if this makes you uncomfortable!!

A part of the LEECH universe by Leafcat (Riifuneko) 

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Katsuki had been walking for hours.

He'd grown used to that, over his time in this world, but that didn't make it any less draining.

The extra weight on his shoulder didn't help, either.

"Oi, Deku," he growled, flicking his slug-like companion in the forehead. "Where can I camp out around here?"

"Well, Kacchan," it began, humming to itself quietly. "There are some quiet spaces further east where travellers won't come across us, but we might be bothered by wild animals. We could climb a tree for the night, but that wouldn't be very comfortable for you. I'll gladly serve as your pillow though!"

"No way in hell," Katsuki countered. "Next?"

"If you turn left at the next fork, there's a little inn where you could rent a room?"

"Lead with that next time, you little shit," Katsuki sighed, plucking the creature off his shoulder and giving it a stern look. "Your wealth of stupid and unnecessary knowledge is the closest to a useful trait that you have, don't ruin it."

"Understood, Kacchan!"

He considered dropping the slug to the ground, maybe even giving it a little kick just for fun, but he was too damn tired to deal with the whining and pouting it would generate. Instead, he shoved it on the other shoulder to balance things out, feeling it nuzzle happily into his neck as it settled.

"Don't you dare," he growled, when Deku stuck its tongue out to lick him. "Keep that shit to yourself."

"Understood."

To Katsuki's relief, Deku remained still and quiet for the rest of the trip, draped limply over his shoulder. It didn't bother to speak until Katsuki had paid for the room and locked them inside, dropping his gear heavily in the corner and throwing Deku at an armchair.

When he was feeling generous, he rented out a room with two beds. He'd learned very quickly that the creature had an affinity for real beds – no matter how many times he offered armchairs or nests more appropriate to his size, Deku was determined to end up in a bed. Usually at Katsuki's expense.

Today he was not feeling generous.

"Are you sleepy, Kacchan?" Deku asked, looking up with shining eyes as he wriggled off the chair. "Shall I tuck you in?"

Katsuki didn't bother to answer him, busy tearing off his sweaty clothing and tossing it at the bed. By the time he glanced back, Deku was already building a nest in it, and he growled at the dopey slug when their eyes met.

"I'm gonna have a bath," he scowled. "Don't do anything weird while I'm gone."

"I'll have a bath too!" Deku declared brightly, hopping down from the bed with a little squish as he hit the wooden floor. "I can wash Kacchan's back!"

"Not a hope in hell."

Deku followed him regardless, eager to help as Katsuki filled a bucket to wash himself. He stepped aside and let Deku splash around a while as he waited for the water to warm up, watching it roll in puddles and lick at a stream of water like the idiot he was. The little dork seemed to be convinced that water meant play.

"Nope," he said sternly, putting his foot down when Deku made for the bathtub. "Not happening."

"But Kacchan!" Deku whined. "Wanna swim!"

"You keep your filthy ass out until I've had my turn."

With a little pout on his squishy face, Deku retreated to hang out in the sink, curling up in the little stone basin. He peeked out over the edge, watching Katsuki step into the hot water with a sigh, his expression softening as he relaxed.

He liked playing in the water a lot, but he didn't mind watching Katsuki enjoy it, either.

"Stop staring at me, you perverted little slug," Katsuki growled, throwing a washcloth and hitting Deku right in the face. "You hiding a pathetic little worm erection in that basin?"

"Kacchan wants to know about my penis?"

"No," Katsuki stopped him quickly. "Get those thoughts out of your head right now."

"If Kacchan gets curious, I'm happy to help him learn!"

"I will never be curious enough to look at your dick."

"I could draw you a picture!"

"No."

With that, Katsuki hauled himself out of the water, and Deku felt a little guilty for making him tense up again. He was about to apologise for making him uncomfortable, but two warm, strong hands wrapping around his body had him immediately distracted. He glanced down at Katsuki's taut muscles, but the view was torn away when Katsuki threw him across the room again.

He landed in the water with a splash that drenched the room, and by the time he rose back to the surface, paddling with his stubby little limbs, Katsuki was gone.

Katsuki needed time to cool off, Deku had learned that facial expression far too well over the time they'd been travelling together. And, well, he shouldn't let the bath go to waste after all.

Katsuki collapsed onto his bed, a little relieved to have some peace from the squeaky slug for once. He could hear the thing splashing around in the bathtub, hopefully wearing itself out enough to sleep without disturbing him. The bed was surprisingly comfortable, too, and he felt himself softening into it, sighing contentedly as his eyes fell closed.

By the time Deku returned, dripping a tiny trail of water across the wooden floorboards, Katsuki was already out for the count. He lay sprawled across the mattress, his head not even entirely on his pillow, dressed only in a pair of soft, loose pants that hung low around his hips.

Deku was a good boy! He had to take care of his Kacchan!

He climbed up onto the bed, slipping his head under the edge of the pillow and pushing hard. It took a few tries, and a lot of effort, but eventually he managed to nudge it far enough to cradle Katsuki's head properly, watching the young man nestle into it.

Step one complete! He was going to need his own quest book, at this rate!

Now, step two: Blankets! He wouldn't want his Kacchan to get cold!

After a few fruitless attempts, scrabbling at them with his stubby little paws, he settled for grabbing the hem in his mouth. He dragged it all the way up to cover Kacchan's bare chest and shoulders, making sure he was all snuggly and warm for the night.

He was such a good boy, making sure his Kacchan was comfortable! There was no way Kacchan wouldn't reward him for being so helpful!

With a happy little hop, Deku wriggled his way under the blanket, curling up against Katsuki's bare chest. If he positioned himself just right, with the way Katsuki lay, he could even feel like Katsuki was cuddling him.

Which was only fair, right? He'd been such a good helper!

For a long while, he snuggled comfortably in Katsuki's arms, breathing contented little sighs. As the night wore on, though, he began to feel twitchy. Katsuki's abs felt so good against him, he couldn't help but rub himself on them just a little. It wasn't like Katsuki would ever know!

He rubbed a little harder, straining to keep himself quiet when he saw how sinfully low Katsuki's pants sat, a little tuft of hair peeking out the top. He was so amazing, so handsome, Deku could hardly be blamed for thinking about him the way he did! Especially with their history.

And maybe... Maybe Katsuki would like to feel good, too? They'd been travelling together for a long time now, and Deku had never seen the man... Well, have fun. So Katsuki was probably pent up! And Deku was just the man – slug – to help him out!

He shifted a little lower, looking up at the peaceful, relaxed expression on Katsuki's face before he melted himself down to slip beneath the loose waistband. It was one of the few benefits of his small, squishy stature – he could easily turn into a sloppy goop to fit through tight spaces. He wasn't sure Katsuki knew about that ability, wasn't sure he wanted Katsuki to know about that ability. He'd probably think the whole thing was pretty gross, after all, and he'd certainly make more of an effort to secure the narrow gaps Deku sneaked through in the night.

Every time the man woke with Deku curled up to him, or licking his face, he always grunted the same words: "How the hell did you get in here?"

Deku just smiled and continued campaigning for snuggles, hoping that one day maybe he would give in, maybe he would pull Deku closer and grumble "fine, whatever" as they went back to sleep together.

For now, though, it let him huddle in the warmth of Katsuki's trousers, wrapping himself around thick thighs and a taut little ass, humming contentedly as he savoured the feel of the tight muscles in his grasp.

It wasn't enough.

He solidified himself again in the dark little cove, the pants stretching to accommodate him, and gave a tentative little lick at Katsuki's buttcheek.

Kacchan always tasted so good.

Katsuki huffed a little in his sleep, but didn't stir or wake, so Deku continued his little trail of licks along the curve of his ass. And if he buried his face between the two pert cheeks, who could blame him? Kacchan was so handsome, so manly and well-built, and Deku was just a lowly little slug monster. He was hardly built with the capacity for self-control.

One strange positive of being so small was that he found he fit perfectly over the curve of Katsuki's ass. When his head nuzzled at the warm little hole, his body draped down the swell of muscular cheeks and fell between perfect thighs. He knew if Katsuki woke up and decided to try it, he could probably be cut in half like a guillotine with those thighs, but the feel of being nestled between them was worth the risk.

He lapped at Katsuki's hole, listening to the tiniest of moans creep between Katsuki's lips, and the sound only spurred him on. He licked a little deeper, drawing more gasps from the sleeping man, until the tight hole began to loosen under his touch. Even down there, he tasted surprisingly good – cleaner than Deku would have expected, although he supposed that could have been his horniness talking.

Deku brought his little paw up to touch, stroking along firm cheeks before he squished it into the hole. Katsuki hummed faintly, squirming in his sleep, and Deku began pumping his paw in and out, stretching the hole a little wider. He knew exactly why he wanted to stretch the man, although he tried to deny it to himself as he worked. He wasn't going to go that far.

Was he?

Every little noise Katsuki made vibrated right through Deku's sludgy body, filling him with pleasure. His dick began to peek out, growing harder as he rubbed against Katsuki's thick thighs and the swell of his backside, his tiny lungs taking huffs of frantic breath as he searched for friction.

He still needed more.

Deku's penis was emerging before he even realised he was doing it, sliding out of his squishy body and rubbing at Katsuki's hole, hardening as the breathing in front of him grew more harried. When he peeked over Katsuki's hip, he found a large bulge staring back at him, Katsuki's face flushed pink and sweaty.

Clearly he was having a nice dream, thanks to Deku's efforts.

He knew he shouldn't go further, knew he should just stop there and be satisfied that they were both happy, but he was still rubbing himself across Katsuki's hole, the arcs of his two-pronged hemipenis taking turns to toy at the opening. Each shaft took turns pressing inside as they passed, sweeping from side to side to give attention to both sensitive tips, precum smearing across everything he touched and leaving slick wet streaks. Deku whined again as he slid his tongue back inside, his own fluid sweet on his tongue, but it mingled with the staleness of his paw and the clean taste of Katsuki’s freshly washed skin.

The next thing he knew, he was pushing his cock inside, gasping for air as he brought himself flush to Katsuki's asscheeks. It was so warm, and his walls squeezed just right around Deku, still just a little bit tight with how far Deku had managed to stretch him. He began to move, slowly at first, but the slick slide of his precum inside Katsuki's hole was too much to resist. 

Moving a little faster, his annoying, squishy body squelched both inside the hole and around it, and his moans became a little longer and louder as he began to thrust in earnest.

"Do you feel nice and full, Kacchan?" he whispered. "I wanna fill you up just right."

When he pushed Katsuki onto his stomach, rolling with him to land on top of his hips without breaking their connection, red eyes fluttered open. Katsuki looked back in a tired daze, as if he wasn't sure what was going on, and Deku's tears finally began to fall when the man grunted at a particularly hard thrust.

"Kacchan, Kacchan!" he moaned, voice choked by his tears. "I'm so sorry, Kacchan, I couldn't help myself!"

Katsuki still didn't say a word, but sweat dripped down his face, and he balled his hands in the sheets tightly.

"You looked so good, Kacchan, so handsome and- and it's been so long Kacchan."

He began to sob, but still his little body moved in harsh slaps, the sound of their motion echoing through the room.

Katsuki opened his mouth, and Deku braced himself to be yelled at, to be shoved away. Any words Katsuki had intended to tear him apart with, though, were lost to the void as Deku hit his prostate. A long, loud moan burst from Katsuki's lungs, and all Deku could do was hit that same spot again and again, tormenting it with every thrust as Katsuki buried his face in the pillow, flushed red and stifling his noises.

"You feel so good, Kacchan," Deku cried. "I missed this so much!"

If he hadn't seen it with his own eyes, he would never have believed the next move Katsuki made. Instead of pulling away, instead of punching him across the room, Katsuki arched his back and pushed his hips back, toward Deku.

"I wanna make you feel so good," Deku sobbed. "Wanna make you feel better than you've ever felt before, Kacchan. Please, please, I wanna see you cum, Kacchan. Kacchan!"

Through the hazy fog of his exhausted brain, addled by the intense pleasure radiating through his body, Katsuki had two thoughts. One: this felt so, so familiar. He could have sworn he'd been there before, lying in the same position as a heavy weight leaned on his back, pressing him into the sheets and filling him up so well. And two: there was something about the slug-monster's dick that made him wish he'd agreed to see the drawing. It stretched him wider every time he moved, rubbing at every wall, hitting his prostate perfectly no matter which way the creature moved or thrust.

Whatever was going on with that dick, he needed to find out. It filled him so much better than anything else he'd felt before, and with his head and heart pounding, all he could think was more, more, more.

He didn't even realise he was cumming until it was too late. The sheets beneath him soaked through with his sticky fluid, but still Deku continued to pound into him, forcing more, more, sending a jolt of electricity up his spine with every touch and milking more and more cum out of his poor, tired dick. He couldn't breathe, couldn't think, all he could do was lie there in his own mess and feel every delicious stroke of Deku's cock between his cheeks.

His dick was flagging, but Deku still moved mercilessly, making him ache with overstimulation. He couldn't say a word, couldn't complain or argue, couldn't even move to roll over and shove the slug off of him. The squishy creature's surprisingly hard dick – surprisingly large dick, for that matter – was like a drug, peeling away his inhibitions and stubborn arguments, turning his biting words into pathetic moans.

Deku noticed the mess, a whole new batch of tears pouring from him when he saw how happy he had made his Kacchan, how much pleasure and joy he had brought to the man beneath him, the man gasping for air as Deku pushed him into the mattress with a strength that surprised even himself. He pried the cheeks apart further with his little paws, sinking himself in deeper, making sure to hit Katsuki's prostate with every ragged stroke.

He knew the man would be in pain, knew every touch would be making him course with that odd ache, but he also remembered words from so long ago, words whimpered at him in a much bigger, more elegant bed. A bed built for two.

"Don't stop, never stop," the man had begged him. "I want it. More, more."

His Kacchan was a master masochist, after all. Nothing made him hard again quicker than the pain and humiliation of being fucked through his recovery period, being pounded ruthlessly even when he felt like he was going to explode from the stimulation.

He leaned in as he continued his rough pace, licking and sucking along Katsuki's lower back. As he trailed his way down pert cheeks, he found himself almost doubled over, watching his cock push in and out through a tight red hole. He slapped his paw down on Katsuki's cheek, leaving a pink mark behind and wishing, not for the first time, that he had hands as big and strong as Katsukis, so he could leave bigger, redder bruises.

Katsuki wriggled beneath him, quiet whimpers finding their way out, a pink flush spreading down his neck and shoulders. Deku wished he could touch every part of him, caress every muscle and kiss every inch of his skin, taste every tear and every bead of sweat the man produced. He could spend hours lavishing that hot, tight body, if only Katsuki would give him the chance.

For now, though, he settled for spanking him again, watching him jolt at the touch and listening to him whine like a pathetic little dog, bucking his hips back into the pronged penis. The slide of his cock through Katsuki's ass was delicious, as if it were made for him, and the sexy thigh muscles squeezed tight and tense on either side of Deku's body, only further accentuating the man's strength.

Deku crawled a little higher, reaching toward the soft curve of Katsuki's back, rubbing his cheek against the smooth skin while his lower body struggled to maintain his pace. He was getting so close, he was so ready, and Katsuki just continued to whimper and moan and choke out half-words that Deku couldn't decipher.

His cock was rapidly hardening again, Deku could see it. It was the hottest thing he'd ever seen in his life.

A long, pleading whine from Katsuki was enough to tip him over the edge. With a moan, Deku shot his load into the tormented hole, his pace slowing but continuing all the same. He pushed his cum deeper into Katsuki's body, filling him up, spurting again and again until it began to squirt out around his dick.

Katsuki came again with a soft moan, barely a trickle of cum managing to squeeze its way out, his dick softening despite valiant efforts to remain. His chest heaved beneath him, his head falling to the side to breathe a little easier, still flushed bright red and sweaty.

Deku began to tremble as he pulled out, his dick hanging limp and pathetic between his stubby legs, retracting a little into his sludgy form. He shuddered, trying desperately to get air into his body, tears pouring down his face again despite his best efforts. He looked down at Katsuki's exhausted frame, his handsome face riddled with confusion and frustration, as if he were still trying to piece together what he just went through. His eyes were glazed, a duller colour than the vibrant scarlet Deku knew and loved, but still he managed to focus his gaze on the shaking monster.

"I'm so sorry," Deku choked. "I don't- I shouldn't- I- I-"

"It's okay," Katsuki said softly, the room falling oddly still around them. "Stupid nerd. You really did your research, didn't you?"

"K-Kacchan?"

"Damn idiot slug," he growled, but with a hint of fondness sneaking into the words that he didn't normally hear. "Come here."

Deku flinched when Katsuki reached for him, preparing to take his beating, to be thrown across the room, or worse: out the window, to be at the mercy of all the creatures of the night.

Instead, Katsuki rolled over, pulling Deku into his lap.

Was he going to beat him up right here? Pummel him with his fists? Pull him apart with his bare hands until he looked like spilled jelly?

"It's okay," Katsuki repeated softly, curling his knees up and settling Deku in the little space it created. His arms even wound around the nest, and Deku realised with a shuddering sob that he was finally getting those cuddles he always dreamed of.

"I kind of feel like we've done this before."

Deku didn't bother to answer the implied question, nuzzling into Katsuki's bare chest and savouring the feel of the man he loved finally holding him again, finally letting him be close and warm, together as one.

"D-Did it feel okay, Kacchan?" he asked quietly.

There was a pause, the room falling silent for a long moment, before Katsuki snorted the faintest of laughs.

"It felt good," he admitted. "Stupid slug.”

“I’m glad!”

“But next time you fuckin' ask first."

"Understood, Kacchan."