Chapter Text
Katsuki Bakugou glanced over his shoulder to make sure he wasn’t being followed, before ducking down a grimy, dimly lit alleyway. He pulled his leather jacket collar up higher to cover the gauze patch over the new bite shaped wound where his neck met his shoulder, and stalked forward until he came to a rusted iron door.
He banged on it twice, paused, then rapped three more times before stepping back to wait, chewing the inside of his cheek. He didn’t want to be seen here. He looked over his shoulder again.
Nothing.
Good.
The door creaked open a crack, rusting hinges grinding out an almost eerie metallic tune as dim yellowish light broke through the darkness of dank, piss stinking alley. Yellow-hazel eyes looked him up and down briefly, before the door opened more quickly, the groan of metal almost a screech in the quiet of the night.
“Were you followed?” Asked a short female omega with bright pink hair, that he’d never met before.
“The fuck do you think I am, an amateur? Let me the hell in, they expect me back in an hour. I told them I was just going out to claim my new mate.” Katsuki growled, barging past her.
The door creaked shut behind him as he marched down a corridor with peeling paint, the lone light in the centre of the walkway flickering. He turned into a concrete room, in slightly better condition than the rest of the shithole building, and stood to attention for a moment before throwing himself down on a black metal fold out chair.
“You got the shit, Sarg?” Katsuki asked gruffly, stuffing his hand into the pocket of his leather jacket to fetch out two glass vials and a sealed plastic sample cup filled almost to the brim with his come. He slammed them on the fold out table between him and the rugged, almost annoyed looking man. “My blood, jizz, and aroused pheromones. Who’s the omega?” He jerked his thumb to the hallway behind them in indication to the woman who had opened the door for him.
“Straight to the point as always, Detective.” Sargent Aizawa nodded his approval and produced a sealed plastic bag with two vials and a sample pot filled with semen in that matched his own, handing it over with another empty bag to put his own in, so that he didn’t touch them. “That’s Ashido Mina, she’s coming over from the human trafficking department with your new partner. How’s the new ‘bite?’” He asked, lifting a finger to scratch at his stubbled chin briefly, still looking as unimpressed as always.
Katsuki pursed his lips for a moment before answering. “Doesn’t feel like a claim at all, but it looks the part. Give it a few days to scab and heal a bit and we’re good to go. Does this asshole have to come to my place? It’s been mine for over a year now. That’s my territory, you know it probably won’t end well.” He warned, before stuffing the bag of his new partner’s samples in his pocket.
“You’re just going to have to learn to get along and not behave like complete knot heads then, aren’t you?” Aizawa rolled his eyes as he stood and cracked his neck. “I’d have gotten Sato to do this, but his wife’s just given birth, so he’s at the hospital. Jacket off, I don’t have all day.” The Sargent said as he lifted his hands and let his Alpha claws burst forth.
“Fuck sake.” Katsuki stood and shucked his jacket, tossing it on the chair. “And that’s easy for you to say when you can take suppressants.” He growled as he bared his teeth. He’d spent the last year and five months almost chomping at the bit, if he was honest. But they were close to a break in the case, and he planned to be back in his own home and in his own bed before they hit the one and a half year mark. Undercover work was something he was practically designed for, with his take no shit attitude and ability to hide what he was thinking, but it still took its toll.
Learning to control his scent without suppressants had been a curveball, but luckily his most prevalent emotion was usually anger, which worked in his favour.
Sargent Aizawa balled his fists and Katsuki set his jaw, before the other alpha punched him straight in the face three times in a row. Katsuki snarled, fingers and toes curling as he tried to keep himself in check while the back of his skull began to pound insistently for him to fight back and rip his boss apart for the affront.
After a few slashes to Katsuki’s chest, back, and the other side of his neck, along with a couple more punches to bruise his biceps and chest a little, Aizawa grabbed a can of pheromone neutraliser and sprayed him down thoroughly to rid him of his scent, before stepping back.
Alpha Alpha matings weren’t exactly tame, and he had to look the part.
“You good, Detective?” Aizawa asked as he picked up Katsuki’s samples and slipped them into his black hoodie. He and Mina couldn’t have dressed like officers to meet him, in case they were discovered. Though Katsuki had made sure no one was even watching him, let alone following him, before coming here.
The gang he was with, the Black Cobras, simply assumed he was going to meet his new mate and claim the man to join them with another gang, so they wouldn’t have suspected a thing.
What was his new partner’s name again? Detective Kiri...shima? Yeah, that sounded about right.
“I’m fine. Now get outta here so I can finish up and head back.” Katsuki drew his top lip back over his gums to bare his descended alpha fangs, before catching himself and taking a calming breath, willing them back into the small slits in his gums above his normal canines.
Aizawa left after a brief nod, and Katsuki heard the heavy iron door close behind him and Mina as they made their exit. He finally released the last breath he’d taken to hold and relaxed his jaw.
Fuck, he missed suppressants.
Katsuki ripped the neck of his black skull shirt, tearing some more sheds into it, before stalking to his jacket to grab the samples from the pocket and set them on the table. There was a face down photograph of his new partner on there too, for him to memorise his description.
They couldn’t actually afford to meet and scent each other yet; their pheromones were likely to give away that they weren’t aroused by the other. It was much more likely that they would have simply attacked one another the second they tried, and it’s not like they could actually claim each other, even if they were miraculously down to fuck. That could royally fuck their sense of loyalty to the investigation.
Nothing came before a claimed mate.
So Katsuki had gone to the dentist, under the pretence of a check up, where he’d had a mould of his top and bottom teeth taken so his claiming bite could be replicated and cut into his partner’s neck surgically instead. The same was true in reverse, though he had no idea what the other Detective’s excuse had been; it could have been taken in a warehouse, a private room in a strip club, wherever the man could get time alone with one of their team.
But Katsuki had gotten a scale and polish out of his, because he’d asked the real dentist nicely. Well, more like told Sero that if the dentist didn’t do it their cover would be blown, and he’d take his anger out on the other Detective. But same thing.
He had also had to deal with a couple of the crew he was with cracking wise about him actually going to the dentist in the first place.
They quickly shut their mouths when Katsuki grabbed one of the bigger betas by the throat, slammed him against the wall and lifted him off his feet to snarl in his face. “Say that again, when I bite your fucking head off with my pretty white teeth.” He had challenged, throwing the idiot’s words back at him.
How the hell was proper oral hygiene not ‘badass’? Fucking criminals.
Katsuki rolled his eyes to himself and flipped the photograph over, feeling his brows rise at the pleasant surprise that was his new temporary ‘mate’. He was built as fuck, with spiked red hair, red eyes, and sharp ass fucking teeth. He was fully naked in the picture, simply hiding his junk with two big hands cupped over his crotch, just like the one Katsuki had had to take a few days ago. Except this guy was grinning in this picture, while he had been scowling in his.
“Tch. Shitty hair, but not bad.” Katsuki conceded with a tilt of his head, eyes roving over the other alpha’s form, taking in the tattooed sleeve on his left arm of red roses, cogs, gears, and a pocket watch, all interwoven with thorny brambles. He had a mole on his right pec, just to the side of his sternum, and a long slashing scar that cut a low angled diagonal across his abs to almost touch his left hip. The rest of his tanned skin was unblemished -Katsuki brought the photo closer to his face- except for a small scar above his right eye.
Okay, details down. He’d burn the picture once he was done here, after one more look at it. He just needed to know enough to be convincing about his ‘mating’ today.
Katsuki had volunteered to be the one in the gang he was undercover within to mate with someone from their rival gang, the Red Dragons, because he knew Detective Kirishima was going to do the same. That’s what their respective departments had been working on for well over a year now; they needed an exclusive shot at a much bigger fish, and they’d heard rumours of the Black Cobras toying with the idea of joining another gang to expand their ‘business’ prospects.
Katsuki hadn’t known his name at the time, only that there was an undercover agent infiltrating the Red Dragons too. Now that he’d seen his photograph, he realised he had seen the other alpha around a few times in passing. He’d never caught a whiff of his scent though.
But he was about to change that.
Katsuki tossed the picture back to the scarred metal table and hung his crumpled jacket on the back of the chair properly, before sitting. He huffed an almost annoyed breath and popped the button on his black jeans, shoving them down to mid thigh, before yanking off his torn shirt and dropping it to the concrete beside his chair. Katsuki took his cock in hand, pumping to work himself up and over the edge as fast as possible, closing his eyes and biting his lip as he concentrated on the feel of his own rough fingers.
It didn’t take long before his knot started to swell, and he wrapped his free hand around it to squeeze as he began to pant. His alpha fangs itched to descend but they didn’t, even as he tipped his head back on his shoulders and groaned in pleasure, working himself faster.
Katsuki squeezed hard around his fully formed knot a few minutes later, breath hitching as come burst from him to paint his abs and chest in lashes, before he slumped back in the chair to catch his breath.
Okay, that took care of his scent of arousal. He fumbled for a moment in his jacket pocket to his side, fishing out a pack of tissues. He used two to clean some of his release away as it began to cool, tossing the soiled tissues into a metal waste bin next to the folding table. There was a small can of accelerant beside it, for him to burn the evidence of his visit once he was done.
Katsuki spread his come a little, bringing dirty fingers to his lips to slide them over his tongue. He liked the taste of himself, but more than that, he wanted to absolutely reek of sex when he dropped by the gang’s hangout to let them all see he’d been successful in bringing the two gangs together; even if he let them believe it was somewhat tentatively for the moment.
The narcotics and human trafficking investigation departments didn’t want them too self assured just yet.
Katsuki grabbed the vial of blood and popped the cap, before taking a tiny sip, intending to spit out any extra once he’d coated the inside of his mouth and maybe dripped a little down his chin for good measure.
His eyes widened slightly and his jaw dropped open as he drew in a surprised breath through his mouth at the rich, earthy metallic taste on his tongue. He looked down at the unassuming glass tube, frowning as he sniffed, nostrils flaring.
It smelled…good?
An involuntary shiver rolled down Katsuki’s spine and he closed his eyes for a moment, sliding his tongue out to lick along his top lip as he tried to decide whether he liked the taste of his partner’s blood or not.
It could be an issue if he did. He’d be much more likely to want to fight the other alpha, or fuck him raw, and the whole idea was for them to get along so that it didn’t impede the investigation.
Katsuki closed the lid firmly and swapped it for the tub of come, wanting to leave the more potent pheromones until last. There was a decent chance of him taking the scent of another alpha’s arousal as a challenge, even without anyone around him to want to fight or fuck.
Detective Bakugou really didn’t like the idea of tasting a stranger’s jizz, even if that person was going to be his ‘mate’ for the foreseeable future. He wrinkled his nose in distaste before he even opened the lid, tensing to try and keep himself in check despite the fact that he was alone.
The scents of arousal and satisfaction curled into the air, imperceptible to anyone without a second gender but a veritable siren to him.
Katsuki bared his teeth immediately, fingers twitching and gripping the plastic cup in his hand tighter as he felt a growl stutter and then start up in his chest. The shadow he often felt in the base most part of his brain perked up, and his eyes darted automatically to the second vial on the folding table; the one full of alpha pheromone liquid, taken directly from his partner’s primary scent gland after he had worked himself up.
They had clearly neutralised the outside of the glass as they had with Katsuki’s, because he couldn’t smell it, and he knew pressing his own glass tube against his puffy scent gland earlier had been a little messy.
Katsuki snatched it up before he could even think about it, flicking the top off with an extended claw. His growl devolved into a low snarl, even as he bought the vial to his nose and drew in a deep breath.
“Alpha.” He growled, lip twitching in anger even as his cock twitched in interest. He flicked his gaze between the come and the pheromones a few times, silently debating, before setting the specimen cup down almost carefully on the table, attention focussed solely on his false mate’s scent.
Katsuki could tell his pupils were expanding, his vision becoming even clearer, crisper, as he stared at clear, almost water-like fluid. There was only a little in the bottom of the vial, but it was more than enough to make him a glaring beacon to anyone with a second gender.
He pressed the open end to one of his wrists and tipped, before rubbing them together. Kirishima’s scent instantly mingled with his own and Katsuki groaned, low and rough and angry as his cock swelled between his legs.
He was almost painfully hard in seconds, breath sawing in and out of his lungs as his eyes darted around the empty room. His claws extended, even his toenails grew into claws in his boots, as he reached up to rip the gauze from his fake claim and toss it into the metal bin.
“The fuck is up with your scent, shitty hair?” Katsuki demanded as he felt his own primary scent gland begin to leak beneath his jaw. He couldn’t even stop himself from lifting the vial to his mouth as he closed his eyes. A drop touched against his bottom lip and another snarl ripped immediately from his chest, eyes snapping open as he gripped the little glass tube tighter. It took almost everything Katsuki had not to crush it completely as an almost violent shiver wracked his frame.
The scent of tree bark, sap, and that strange smell of ozone that came after heavy rainfall surrounded him.
He wanted it on him.
Katsuki licked the drop of concentrated woodland from his lip, feeling his vision narrow as his pupils snapped to slits. He switched hands, holding the vial with come covered fingers to drip a little onto the fingertips of his clean hand, before rubbing them gently around and over his ‘claim’. His cock twitched, fresh pre-come practically drooling from the tip to mingle with the recent spend still soaking his length.
Katsuki hadn’t expected to want to come again while he rubbed himself down with the scent of a strange alpha’s desire, but there he was, shifting to part his legs as his hips rolled up involuntarily, aching for friction on his throbbing cock as he tipped the vial again and let two drops splatter between his pecs. Kirishima’s scent filled his senses until there was a thunder cloud rolling and toiling in the back of his skull and his alpha canines descended to puncture his bottom lip.
Giving up all pretence of control, Katsuki tipped the remaining pheromone fluid into his palm, tossing the vial away to smash in the bottom of the metal bin. He slapped his hands together to spread it, before smearing heady arousal all over his chest and collarbones, down his abs and up his neck to his own scent glands.
Katsuki knew he was growling too loudly, but he was alone and he didn’t give a shit. He dropped forward from the folding chair, landing on his knees with a thud as his tongue lolled out from his mouth in a heavy pant.
Fuck.
He had no hope of stopping himself from reaching for the specimen jar of his new partner’s come and shoving his tongue into it.
The second Katsuki felt that it was cool he both whined and snarled at the same time, the claws of his free hand gouging into concrete as he twitched, agitated. Not right. He should have sucked it right from the other alpha’s cock. Bent him to his will. Fought him into submission and fucked him to show that he was the one in charge.
Should have bitten him.
Katsuki’s back arched as he reared up to his knees again, grabbing for the vial of blood. He ripped the stopper out with his teeth and spat it away uncaringly, before pouring half straight into his mouth and swallowing.
What the fuck was he doing?
It was supposed to be an act, a sham. He wasn’t supposed to be losing his goddamn mind in a semi abandoned building over a few shitty samples. Samples that happened to smell so good they made him want to purr.
Bakugou had never had this kind of trouble controlling himself before.
But the next second he was setting the come on the floor and shoving clawed fingers into it to slick them, before immediately wrapping his hand around his aching cock, pumping hard and rough as he spread his knees and arched to throw his head back.
Katsuki closed his eyes and imagined the redhead from the picture, letting instinct take over instead of fighting it as he usually did.
They were fighting. He was bigger, stronger. He pinned the other detective and sank his teeth deep as he shredded his uniform. Then suddenly they were rolling, each trying to subdue the other to fuck them down into the earth that he could smell in Kirishima’s rich scent.
Katsuki poured the last of the blood over his lips, licking them as the rest ran to drip from his chin and down his neck. He smeared it in, then all up one cheek and into the side of his hair as he picked up the pace, hips thrusting automatically into his fist as he chuffed heated breaths into the stale cold air of the room.
He needed more.
Katsuki grabbed the specimen pot and upended it over his chest, dropping it immediately to rub his mate’s release all over himself as he brought himself closer to the edge almost viciously, teeth bared and alpha canines descended as he panted, mouth wide open and smeared with blood.
“Alpha.” He growled, that cloying mix of anger and arousal warring within him as his still half inflated knot began to swell even more, hitting the bottom of his fist with every desperate downstroke.
What Katsuki wouldn’t give right then to have it catching on that redhead’s rim, until he stuffed it deep and let himself go, teeth buried just as deep in tanned flesh.
Katsuki dropped forward, slapping his now free hand to concrete as his back rounded out like he was bearing down and his body tensed. He tasted his own blood as heat shot straight to his cock at the image his mind supplied, before come pumped from him onto the dirty floor between his legs and his eyes rolled back in his head. He heard it splatter against concrete like a stuttering tap as he emptied himself with a low, relieved groan, a shiver rolling down his spine like an electric current.
“Fuck.” Katsuki gasped in several harsh breaths to try and calm himself, quickly snatching his hand from his cock before his stupid alpha brain got any ideas about a round three. His hands were shaking as he sat back on his haunches, and it took several seconds before he thought he might be able to stand without his knees giving out on him immediately.
He needed to clean the place up, get rid of the evidence of his visit, and get the hell out of there.
How goddamn embarrassing.
He couldn’t wait to get back on suppressants, so that shit like this never happened again.
Katsuki finally stood and stuffed his cock back into his boxers with a hissed in breath at how sensitive he was. His knot felt squashed and trapped as he gingerly zipped himself up, before he shook his head to clear it and snatched up the can of lighter fluid.
Stupid ass woodsy smelling Detective.
Just over ten minutes later Katsuki emerged from the alleyway, leather jacket collar up and head hung low to hide his come and blood smeared face as he marched down the street and took a corner. He took another and stalked down a side street, finally reaching his motorcycle.
Katsuki unchained his helmet and shoved it straight on his head, sliding the visor down as he slung his leg over the hog and jammed his keys in the ignition. He was still so high strung that he probably shouldn’t be driving, but he had to get back before one of the gang called to check in. He took a few calming breaths and set off, streetlights whizzing past as the cool night air whipped and stung at his new fake claim.
Katsuki wasn’t looking forward to having to deal with a new partner after this long going it alone, and he had no idea what the other detective was even like, let alone if they could work well together.
Especially now he knew what the man’s blood and come tasted like.
Shit.