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The moon lights up the sky on a Saturday evening as Katsuki walks home from his double shift.
His legs are cramping with overexertion, the muscles screaming at him to stop moving and sit down. However he ignores it in favor of getting back to his and Eijirou’s shared apartment.
Once he gets there, he knows that there are a few gummies to lessen the pain temporarily while he showers and eats until he inevitably passes out in his bed for the evening.
A crash of something in a nearby alleyway has him stopping in his tracks. Not because he’s asking for a fight, or wanting to inspect it.
It’s the fact that the yelp that accompanies it sounds just like Eijirou’s.
With reluctance, he waits it out for a few more seconds to see if there are any other noises leaving whoever bumped into something down the narrow opening-
“S-shit…”
It’s definitely Eijirou.
Katsuki twists to go down the passage, still on guard should someone be using his voice or he happens to be wrong and someone simply sounds like the redhead.
His questions are answered as he turns into a small alcove, and there he is. Crouched down in a squatting position doing...something.
“Ei?” he asks, and the redhead turns so quickly it makes him jump. “The fuck are you-”
A whimper escapes Eijirou, sounding on the verge of panic and desperation. He is covered in blood, decorating his skin from his neck down to his stomach. Katsuki reaches a hand out in worry-
“DON’T TOUCH ME!” The redhead yells, pushing back until he is pressed against the alcove’s wall. “You...you need to get away, Katsuki.” He warbles, almost sounding on the verge of crying. His hands come up to grab at his hair in a tight grip. “I don’t want to hurt you, so please…”
Katsuki doesn’t understand what Eijirou is going on about, but does take a few steps back like Eijirou basically demanded him to do. He isn’t about to cower away from his best friend, especially when he sees that something is wrong with him.
He can't leave the man he's infatuated with.
“Eijirou, tell me what’s going on.” He speaks softly to coax the redhead into explaining himself. “I want to help you, but I can’t if you don’t let me near you.”
“I can’t...I can’t-” he lets out a sob, tears falling down his cheeks. He’s looking away from Katsuki. “Your pulse. It’s too loud.”
The blond blinks in confusion. “My...pulse?”
“Yes, Katsuki, your pulse! I got hit by a quirk that-” he cuts off as a growl leaves his chest, and then stops as Eijirou groans like he’s fighting it. “ Get away now, Katsuki. ”
Katsuki stands there for a moment longer when Eijirou glances up at him, and he gasps.
Eijirou’s normally vermillion eyes are glowing , and his teeth are bared, but two pointed teeth elongate out of his gums to sit below his lower lip.
Katsuki knows now.
So he runs.
He’s heard of the villain that got a hold of Eijirou. The man holds a quirk that shifts people into blood-sucking fiends for a day or two, craving it like a vampire would. They can only feed off of humans; animals make them throw up and end up being null and void. If whoever gets hit doesn’t get their fill, they begin to go insane and their bodies start to collapse.
Yet Eijirou is fighting it. And it’s making him go feral.
Katsuki finding the redhead right when he starts going into it is like death calls out for him. Or so the blond thinks. They share a living space, for crying out loud! And Eijirou will absolutely fight tooth and nail so he does not have to hurt anyone.
Until now, where he truly can't stop it even if he wants to.
A roar from the blond's best friend has him sprinting back to their place, legs disregarding the pain when he takes steps two at a time. He’s panting, hearing Eijirou right on his tail.
Right before he opens the door, a hand slaps next to his head. Katsuki pauses, eyes wide at the pointed fingernails escaping his best friend’s hand.
He feels the redhead’s breath on the nape of his neck, and shivers when he sniffs him. “Katsuki…” he whispers, “You smell so good right now.”
The blond shakes out an exhale, hand still poised on the doorknob to the apartment. “Eijirou.” he says, trying to keep his voice steady. “We need to get inside. I’ll...I’ll let you feed if we get into the apartment.” He won’t. He’ll figure something out one way or another. Maybe he’ll lock the redhead inside when he pushes him in.
Eijirou hums in contemplation, still not moving from where he had placed himself behind Katsuki, chest to back. He sniffs again, and then moves his hand, shuffling back. “Fine.” he mutters, cadence completely different from what Katsuki is used to.
He carefully opens the door, but the redhead will not go in before Katsuki does. Sighing, he gestures Eijirou in after him. The redhead looks ready to attack, hands by his sides but staring a hole into Katsuki’s neck.
Katsuki is thankful that Eijirou still has some control to do this simple thing, but it doesn’t last long.
When the door closes, they don’t even leave the entranceway. Eijirou slams Katsuki bodily into the wall, back hitting it with a thud. Katsuki grunts at the impact, not having a chance when Eijirou pushes in, mouth already pressing along his neck.
“Ei...Ei wait-”
“Can’t.” The redhead says, licking a trail up the line of Katsuki's collarbone and opens his mouth, saliva dripping onto the blond’s warm neck. “Need you.”
Then he bites down, breaking the skin.
Katsuki cries out at the pain that envelops him. It’s awful, sending tremors of fear down his spine. What if Eijirou really has no control and keeps taking more and more until Katsuki passes out, or worse? The logistics of the quirk are lost to him.
His explosion quirk already does fuck all to the redhead due to his hardening, so there is no way of getting out of this. The only thing he can muster is grabbing at red hair and pulling to try and yank his best friend off. “Eiji-ahh…”
What starts out as insufferable agony transitions to pure pleasure once Eijirou begins to suck in, sloppy noises escaping from his lips. Katsuki’s eyes roll to the back of his head, blood rushing down to his groin. His hand clasping onto red strands pushes him in instead of trying to pry him off, moaning at the sensation.
Eijirou hums in agreement, still taking in mouthfuls of blood, swallowing with an audible gulp. Katsuki can feel his veins emptying along his neck, but he can’t bring himself to care. He humps up into Eijirou’s thigh to get friction of any kind, hard in his pants.
The redhead suddenly reels back, mouth detaching from Katsuki’s neck to rush backwards and hit the wall opposite of Katsuki. His lips tinged red from the blood, a drop of it trailing down to his chin.
“Oh god, oh god, oh no I’ve hurt you, Kat I’m so sorry-” he starts crying, putting both of his hands on his face and slouching down onto the ground. “What have I done? I’m such a terrible person-”
Katsuki comes back to his senses seeing his best friend on the ground in hysterics. He blinks in surprise, two large holes still open on the side of his neck, dick still attempting to get any attention.
“Hey hey, it’s okay, Eijirou.” Katsuki says, consoling the redhead with a hand on his hair. “It’s alright-”
“It’s not!” Eijirou howls, raising his head up to stare at the blond. “I hurt you, and-”
Katsuki’s hands come up to Eijirou’s face, cupping it in between them. The redhead’s breath hitches. “Calm down, Red.” Katsuki murmurs, a thumb brushing along the red line going down from his bottom lip. “I’m glad you pulled away, but I didn’t mind it.”
Eijirou furrows his brow, “You...you didn’t?”
Katsuki huffs out a laugh. “No, idiot. It felt fucking good." he responds, and then sighs. He stands back up, reaching a hand out to have Eijirou grab onto it. “Come on.”
He pulls them away from the entrance, sitting both of them down on the couch. His neck is still covered in blood, and Katsuki can tell that Eijirou is honing in on it like it’s the best meal he’s ever had.
To be fair though, with the quirk in place it probably tastes as such, so Katsuki understands somewhat.
Once they position themselves on the couch, Katsuki does the unexpected, and arches his neck towards Eijirou again. “I know you want more, dumbass.”
Eijirou leans back, shaking his head and moving his hands in front of him. “No no! I’m not doing that again to you.”
Then the redhead’s eyes move down to the bulge in Katsuki’s pants. “Wait. Did you-”
“Get turned on by you biting me? Yeah.” Katsuki answers like it’s obvious. Eijirou sputters, face going red with a blush.
Katsuki moves forward more, getting into Eijirou’s space. “Do it, Ei.” He tilts his head again, baring himself again. “Feed off of me.”
Then adds on in a whisper, “I trust you.”
The power the redhead has over his body diminishes, and he quickly bites right back into the two holes.
Katsuki mewls. “Yes. Good boy, Ei.” He whimpers, hands coming up to hold Eijirou’s head in place as he drinks.
Eijirou shuffles closer to Katsuki, a hand coming up to cup the side of his jaw, groaning at the thickness of his best friend’s sweet blood. It runs down his throat in waves, tasting like the best food in the world.
His jeans start to get tight as he continues, listening to the little noises of content coming from the blond that has not complained once. Katsuki whines, thrusting into the air, “feel s’good…” he slurs. “Don’t stop…”
But the sound of Katsuki’s voice breaking pulls Eijirou out of it, and he reigns back, blood dropping onto Katsuki and rolling down in rivulets from the redhead’s fangs. “Shit, Kat I think I took too much,” he says, licking lightly at the points on the blond’s neck to clean up the excess blood. His fangs retract, turning back into his normal sharp teeth.
Katsuki moans at the wet muscle running along the marks, and without thinking, he shifts his head over once the redhead moves away and laps up the red from Eijirou’s teeth, tasting his own metallic blood.
Eijirou gasps in surprise, eyes lidding a moment later when Katsuki pulls back and stares at him, pupils dark with lust.
He nudges his nose against the redhead’s, breathing out. "Jesus, why is this so damn hot?"
Eijirou doesn't move, can't move. He's stuck in shock at the closeness of their faces, the smell of Katsuki's blood staining the air that they breathe in and out.
Then the blond pushes in, kissing Eijirou softly. It's chaste, short and sweet. He pulls back, and gently speaks.
"I want you to fuck me, Ei.”
The redhead's mind shuts down and reboots, doing a double take at the words that left his best friend. "W-what? How did- why now- do you like me?"
Katsuki groans, grabbing a handful of Eijirou's shirt and gripping it tight. "I'm in love with you. Have been for years, you oblivious ass buffoon. Do you love me too? Yes or no."
Eijirou pauses and then laughs. "I think you are the oblivious one, Katsuki!" He says happily. "I've loved you since our first year in high school. So to answer your question, yes."
Katsuki nods once, grunting in acknowledgement. "Cool. We're both idiots. Now that that's out of the way…" he nips at Eijirou's bottom lip lightly, and smirks. "From what I can remember, I told you to fuck me, Eijirou."
The redhead's expression changes on a dime, and he snarls at the demand, kissing Katsuki hard. Both of them can taste Katsuki’s blood on their lips but they can give less of a shit. Eijirou lifts Katsuki up bodily, having the blond wrap his legs around Eijirou’s waist while he walks them to Katsuki's bedroom.
He slams the door open, tongues connecting and embracing the spicy aftertaste of Katsuki. Eijirou throws Katsuki onto the bed, immediately straddling him and kissing him over and over.
Katsuki tears from Eijirou’s lips to grab at the back of his head, reeling it into his neck again. “Bite me.”
Eijirou complies, fangs coming back out and plunging in, wrenching out a moan from the blond underneath him. While he takes in the sweet nectar of his best friend, he fumbles Katsuki’s zipper and button with one hand, having the blond pull the pants the rest of the way off.
His hand grabs onto Katsuki's cock, stroking it in time with each drop of blood that lands on his tongue.
"God, fuck yes." Katsuki breathes, and Eijirou can hear his heartbeat going insane.
Eijirou yanks back, and Katsuki suddenly puts two fingers up to his neck, wincing at the sensitivity. He coats them in his own blood, and moves them down-
"Kat, what are you doing?"
The blond glares, "the fuck does it look like?" He asks, rhetorically. "I'm gonna finger my ass, idiot."
"With blood?! " He questions loud, eyes wide. "That's not enough, man! Let me get some lube or something at least!"
Katsuki shakes his head, rolling his index finger around his rim. "Ran out the other night." He states, "and unless you want to leave me alone to go and get your own lube from your room across the apartment then be my guest."
Eijirou intrudes, "No." He pushes in, both arms surrounding Katsuki's head. "I'm not leaving."
Katsuki smirks, "Then you better give me something else to work with."
The redhead thinks and then leans down and spits directly onto the blond's hole. He does it a few times until it's wet, and Katsuki nods in approval.
Eijirou moans at the sight. His best friend, hand by his asshole, dripping in spit and blood.
It's amazing.
After deeming it enough, Katsuki pushes one of his fingers into his asshole with a hiss.
It burns for a moment until he starts pumping it in and out, moving up to two in a matter of minutes.
While that's happening, Eijirou is licking and barely nibbling his teeth on different parts of Katsuki's body, fangs on display and scratching along the reddened skin. The blond is making the most gorgeous of noises, arching into the touch and brushing his fingers on the spot that has him seeing stars.
Katsuki pulls his fingers out after enough stretching and he lays back, grabbing at the redhead. "Fuck me."
Eijirou listens, rolling his hips right into Katsuki's, connecting them with a squelch.
The blond hisses out a breath, not realizing how fucking big Eijirou is. "H-hold on a second, give me a minute." And they sit there, waiting for Katsuki's ass muscles to relax.
The redhead moves in, nuzzling his nose against Katsuki's gently. Despite the situation, he's wanted to do this with his best friend for years. He just wishes that it was under different circumstances.
Yet, he's okay with this. He hopes that Katsuki feels the same and that this isn't some insane spur of the moment thing.
"Okay." Katsuki says, putting his hands around Eijirou's neck and spreading his legs more. "Go."
Eijirou pulls out only to rush back in, balls slapping against Katsuki's taint. The blond cries out, eyes widening at the sheer girth of the redhead's cock rearranging his guts around.
"Shit, shit, Ei -" the blond pants out, feeling out of breath. "Eijirou, you're so big ."
Eijirou moans at the praise, starting to thrust in faster. Katsuki seems to be completely okay with it by the sounds of his wails echoing off the walls.
"FUCK! Bi-bite me again, you shitty twilight-wannabe!" Katsuki yells, and Eijirou does just that, lapping lightly at the blood that escapes.
They fuck quick and rough, the headboard of Katsuki's bed rocking with the force of it all. The blond holds onto the sheets with a Thor-leveled grip, knuckles turning white from it. Sweat drips off of Eijirou's body, both of them panting hard.
"Kat, you taste phenomenal. So good. So damn sweet…" Eijirou mutters, tongue cupping around the blood that pools near his best friend's collarbone. " So perfect ."
With that alone, Katsuki's orgasm hits him like a freight train, and he cums hard while Eijirou licks at the two markings on his neck like it's saccharine honey.
"Katsuki, Katsuki, Kat-" Eijirou grits his teeth together, fangs overlapping over his lip as he cums into his best friend.
They take a second to breathe, feeling like they ran a marathon. Katsuki knows his neck and ass are going to be bruised to shit tomorrow. He'll probably just call in-
"Do you know how long I'm supposed to be this way, Kat?"
The blond looks at Eijirou who had pulled out and laid next to him. "Maybe we can get into the database and figure it out later."
Eijirou blinks. "Later? Why don't you want to do it now?"
Katsuki stares at his best friend, brushing his lips along his. He smirks. "Because, Eijirou." Katsuki's eyes twinkle with mischief as he maneuvers himself over the redhead's body, straddling him.
"I'm not done with you yet."