Chapter Text
It was common knowledge that all slayers, around the age of 18, tsuchinoto rank and above were required to have a designated heat and rut partner to pair up with whenever one or both slayers' mating cycles occur. Each slayer is given the option to choose their designated partner, however both parties must agree to being each other's partner, if a slayer didn't choose a designated partner within six months a partner would be assigned to them at random.
Those who already had mates weren't assigned a cycle partner since one's own mate would be more than suitable to take care of their heat or rut. Of course betas were excempt from this rule since they didn't experience any mating cycles that required them to be out of the field for almost a week.
Unfortunately for Genya ever since he reached the tsuchinoto rank, six months ago, his scary appearance, awkwardness around women, gruff, straightforward personality, and slight social anxiety prevented him from being able to find a cycle partner. But now, he sat awkwardly in his assigned room, at the butterfly estate, waiting for his new designated cycle partner to show. The alpha let out a sigh as he laid back on the bed covering his eyes with his right arm.
He must of nodded off, because he was soon awoken by the sound of angry footsteps making their way down the hall and to his room. Genya sat up looking on as his designated partner fiddled with the lock on the door, Genya blushed a small bit wondering what omega had been assigned to him, just as the alpha was about to get up to open the door it suddenly unlocked and flung open. Any and all hopes for a cute and gentle omega were soon smashed as Genya was met with the sight of a familiar boar headed omega, the one and only, Inosuke Hashibira.
The hair on the back of Genya's neck stood up. Of all the omega's they could have picked, why did it have to be him?!? Honestly if Genya truly didn't want to pair up with Inosuke he didn't have to, he could ask to spend his rut on his own then later he could submit request to be reassigned to another cycle partner. Sure it definitely would take much longer for his rut to end but at least he didn't have to deal with the feral omega that stood before him.
"So, you're the alpha they deemed worthy enough for the Great Lord Inosuke? Tch, I'll be the judge of that!" The omega huffed and firmly planted his hands on his hips as he stared the alpha down. With his mask on Genya couldn't tell just what his expression was, but he could feel the omega's analyzing gaze on him as he sized up his potential partner. Genya sat back on the bed with his knees under him furrowing his brow. It wasn't that Genya thought the omega wasn't attractive, or that Inosuke wasn't good enough for him, it was just that the two always seemed to butt heads whenever they spoke seemingly over any meaningless thing.
To be perfectly honest, Genya thought Inosuke was rather attractive, for a male omega, especially since Genya preferred female omegas over males, Genya couldn't help but feel attracted to him. Inosuke's body was impressively flexible and finely sculpted from years of training, fighting, and exercising. Though he was a bit on the small side Inosuke could still handle himself in a fight. Genya once again couldn't help but admire him, but despite all that Inosuke was an expert on getting under Genya's skin. He'd steal food, start fights, insult him, make jabs at Himejima or Sanemi, and he'd even pick on Genya for not being able to use breathing techniques.
Annoyed, Genya snapped at him. "Well? Are you just gonna stand there? Or-" but before Genya could finish his sentence the door was once again locked and the green eyed omega was now sitting in front of him. Genya, still caught off guard by the omega's quick movements, blushed a little as the omega removed the boar head to meet his gaze. The alpha quickly looked away not wanting to acknowledge the fact that he was already blushing, despite nothing having happened.
"You don't look so tough, I can easily take you." Genya closed his eyes not wanting to look at him does he even know what he's saying?? Inosuke smirked as he noticed the alpha's face reddening. "What's wrong? Can't handle the presence of Lord Inosuke?" Genya finally looked at the omega and huffed. "Of all omega's they could have paired me up with, why you?? Do you even understand why we're here?" Genya snapped at the feral omega once more. "Of course I do! I'm not an idiot!!" That was debatable, Genya looked at the omega with a skeptical gaze.
"And what exactly do you think we were paired up for?" The alpha pressed the question further. From what he heard, from Tanjiro, Inosuke didn't quite understand most social interactions, and Genya sure as hell wasn't about to take advantage of a navie omega. Especially if he didn't actually understand what was going on. "They paired us up to mate-" "WE DEFINITELY AREN'T DOING THAT." Genya shouted, he wasn't about to mark some omega he barely knew or didn't get along with. "Huh?! Then why did they say you were gonna help me get through my heat?! And that I was supposed to help you through your rut!? Isn't that mating?!?" Inosuke looked frustrated and confused.
Genya paused for a moment, groaned, and pinched his nose bridge before he spoke. "There's a difference between mating and helping someone through a mating cycle. We'd only be mating if we claimed each other. I'm not gonna claim some random omega." Inosuke looked at him for a moment, as he took in the new information, he seemed to relax once he understood that he wasn't going to be claimed, it made Genya feel a little sorry for the omega.
Inosuke must have been worried about the idea of not being able to choose whether or not he was claimed. "...Did you think that the requirement for a 'heat and rut partner' meant you had to be claimed..?" The alpha softened his voice as he began to understand the younger man. Inosuke looked down and nodded.
Genya hadn't really thought about it before, but now it made sense to him why Inosuke had been randomly assigned to him instead of being paired up with someone of his choice. He didn't want to be claimed, so he probably thought if he didn't choose a cycle partner he wouldn't be, but despite that he ended being assigned to one anyway. "..Hey, if you're not comfortable being with an alpha for your heat you don't need to do this. Just tell Shinobu you wanna spend it alone. I'm sure she'll understand. " Genya tried his best to comfort Inosuke now that he could see that the omega had only been acting tough earlier.
Inosuke looked up at him and thought for a moment before he shook his head. "No, I'm not scared of being with an alpha for my heat..I just didn't want to be claimed yet." Genya was genuinely surprised that Inosuke was being so vulnerable in front of him, especially since the two almost never got along.
He guessed that it was just Inosuke's pre-heat hormones affecting him and making him more sensitive. "Alright then, we'll do this together." The alpha couldn't help but feel a bit better about the situation when he saw the omega once again feel comforted by his words.
What Genya wasn't prepared for was the sudden change in moods once their pre-heat and pre-rut instincts began to kick in. Feeling enticed by the alpha's sudden change scent Inosuke moved closer, Genya leaned in as he too was drawn in by Inosuke's new scent. Inosuke, feeling his confidence returning, took the lead and pressed their lips together while placing his hand on the other's shoulder for support. Genya kissed the omega back and placing his hand on the back of Inosuke's head to bring him in closer.
Inosuke straddled Genya's hips as their kissing soon turned into a heated make out session their tongues fighting for dominance as they explored each other's mouths, their hands felt up each other's bodies, and their scents mixed with one another's. When the two pulled apart for air, their eyes met, and suddenly whatever prior grievances they had with each other didn't matter anymore. Not when they had one another so close, not when they felt so warm in each other's arms, and definitely not when every part of them screamed out to be one with the other.
The alpha paused, "Before anything happens, I want us to have a safe word. If one of us says 'katana,' everything stops, okay?" " got it. 'Katana,' okay." Inosuke nodded firmly in reply.
Without another word, Genya kissed Inosuke once more as the omega ripped open his yukata. The older demon slayer groaned when he felt the omega's hand reach into his fundoshi and pull his co*ck free. Inosuke's eyes widened as he practically yelped, when he looked down, seeing just how big the alpha was. Genya felt somewhat proud of himself as he watched the little omega measure the size of his dick with his hands and compare it to stomach. Inosuke turned bright red as the realization, of just how deep inside the alpha would go, hit him. "What's wrong? Don't think it'll fit?" The alpha chuckled, enjoying the look on Inosuke's face.
He sputtered for a bit before growling at the alpha. "I can take you no problem!" Inosuke tore his clothing off and lifted himself up before lining up the alpha's hard co*ck with his c*nt. "Wait, shouldn't I prep you f-URST!~" Genya was cut off by his own moan as the omega slid himself down onto his co*ck in one fast and fluid motion. Inosuke moaned loudly as he was filled up by Genya's thick co*ck. The two panted, Inosuke, now firmly seated in Genya's lap, groaned feeling the alpha now balls deep inside his vagin*.
"f*ck, that was hot, you're so damn tight." Genya peppered the omega's face with kisses that trailed down his neck while bucking his hips upwards, Inosuke whimpered as he adjusted to the alpha's size. "I-it's ngh, nothing...s-ee..?" The omega struggled to get his sentence out he was too distracted by the co*ck, that sat now heavily inside his c*nt, to focus properly on what he was saying. Once Inosuke caught his breath he wrapped his legs around Genya's hips, placed his hands firmly on the violet eyed alpha's shoulders for support, and began to slowly roll his hips back and forth.
Genya groaned, placing his hands on the green eyed omega's hips to keep their pace steady. Once he found a good steady pace, Inosuke began to ride the alpha a little faster. "Hahh ahhh, ngh~ fuuuuck~" Genya groaned, he smacked Inosuke's ass, and began thrusting upwards into the omega. Inosuke yelped, then moaned as he bounced harder and faster on the alpha's dick. The alpha firmly held the omega's hips, lifting him up and down on his co*ck.
"Ooh!! Sh-iiit!~ yes!! Ri- hahh- right there!!~" Inosuke howled as Genya's co*ckhead began bullying his cervix over and over again. "Ngh, f*ck. Ya like that? Huh? You like it when I f*ck you like this? When I f*ck you like a slu*t?" The alpha growled, treating the omega more like his own personal sex toy. "Ungh! F-f*ck, Y-ESS!!~" throwing his head back the omega moaned pathetically in the alpha's lap, loving every second of the rough treatment. Genya hissed and bit down, hard, into Inosuke's shoulder while the omega clawed as his back, which only served to encourage the alpha to get rougher with him.
"M-more!!! Mmh~ hngh, y-yes!! Ooh!~" Inosuke moaned as Genya's thrusts became impossibly deeper. "So b-ig!!!~" The smaller slayer whimpered. "if I'd 'ave known- ngh- you were such a- f*ck..-s-such a slu*t, I'da f*cked ya sooner!" Genya growled in his ear, Inosuke sobbed in absolute pleasure as Genya rearranged his guts. "F-f*ck you.."
"Ah..haah, that's the p-plan" Genya panted out, lifting the omega up, 'til only the head of his co*ck was still inside, and slamming him back down. Inosuke let out the loudest moan Genya heard him make the whole night as his org*sm slammed into him like a truck, slick gushing out around the violet eyed alpha's co*ck, and his cum spurting out onto his belly. Genya hissed through his teeth as the omega's puss* tightened up around him, his own thrusts became more sporadic and desperate as he chased his own org*sm.
"f*ck. You really like that, huh?" Genya teased as he pressed his hand down onto Inosuke's belly where his co*ck had been making his stomach buldge. Inosuke moaned louder, shaking and clinging desperately to his partner, Genya kissed him and nuzzled his cheek agasint the omega's. "Hah, f-f*ck, you're doing so good...so..so good.." Genya moaned, closing his eyes tightly, and pressed his forehead against Inosuke's. "Ngh, 'm close.." the alpha groaned feeling his knot start to swell at the base of his co*ck.
"Mngh, I-I want it s..so bad~" Inosuke sobbed wrapping his legs tighter around Genya's hips. "Haah, ngh, 'm gonna give it to ya, don' worry~" The alpha panted as he thrusted faster into the black and blue haired omega's c*nt. "FUUUUCK!!!~" Inosuke yelped as he felt the alpha's knot pop into him "NNGH, f*ck!" Genya howled as he came deep inside Inosuke. The two were nothing but a panting, whimpering, shaking mess as the alpha filled up the omega's womb up with his cum.
Inosuke panted, hugging Genya tighter, and rested his chin on Genya's shoulder, as he panted, listening to the alpha's breath hitch with each spurt of cum. "Holly hell, that was so damn good.." Inosuke nuzzled his partner and rubbed his back. Genya hummed in agreement as he nuzzled the omega back. "You were so good, Ino." He turned to kiss the omega on his cheek once more. Inosuke bathed in the alpha's affection while the two caught their breath and regained their energy.
After only 10 minutes, their eyes met once again, and the two didn't need to say another word before Genya tackled the omega forwards onto the bed for another round. The two would definitely be at it for a while.
