Thread by @FryingPanWrites

CW: NSFW, abo, selfcest, alpha!Kiri, alpha!Baku, ph Kiri, ph Baku, hs Kiri, time travel shenanigans

Kirishima did not expect to the day to be any different while on patrol with FatGum.

He really didn't.

But that's what happened.

And now here he is staring up at his boyfriend.

Who happens to be a great taller then him with arms that make him want to drool, an undercut, and a waist that Kirishima was pretty sure he could wrap his hands around.

"Well I'll be damned. He was right."

Oh God his voice.

"Ka-"

"Shut up mini Shitty Hair and follow me."

Kirishima's jaw clicked shut. He could barely smell his boyfriend, but that made sense since he had on duty. Surpressents and scent patches. He could see one on Katsuki's neck as well, over what looked like a mating bite.

MATING BITE!?

"Come on! We don't have all day!"

Katsuki had climbed onto a motorcycle, painted red, orange and black, and holding out a red helmet.

"I know you don't need it but put it on anyway." The blond said cutting off Kirishima's train of thought.

The helmet was a bit big but okay.

He climbed on behind his boyfriend (?).

"Hold on tight."

Katsuki revved the engine once and then they were off. Kirishima never held onto someone so tightly. His forehead rested directly between the blond's shoulder blades.

The height difference was going to kill him.

One very fast and scary ride later, they pulled into an underground garage.

"Where are we?" Kirishima asked, dismounting the bike.

"Our agency." Katsuki walked off to an elevator.

"Our? As in-"

"Yes. Yours and mine."

His jaw dropped. Katsuki had talked about wanting to start an agency together after they got on their feet as heroes. And here it was.

"Hurry up! Geez, I seriously don't remember you being this slow!"

Kirishima practically jumped into the elevator.

"I'm in the future."

"Duh."

Katsuki pressed a button and the elevator ascended.

"So we're-"

"Yup."

"You didn't even-"

"Yes we're mated. Yes we're hero partners. No, I'm not number one yet but we're both in the top ten."

And there were all his questions.

The doors opened to reveal not an office like he thought, but an apartment.

The smell of grilled meat filled the air.

"Kat!"

Kirishima almost fainted.

Coming around the corner was himself except a whole lot bigger.

Red and black hair pulled into a top knot and an undercut matching Katsuki's. Muscles on top of muscles on top of muscles. And he was /tall/. Katsuki had to stand up on his toes to give the giant him a kiss.

"Right where you said you'd be."

"Told you."

Oh, that's the floor.

"Eijirou."

Katsuki's voice. His boyfriend. His future mate.

"Eijirou, wake up."

He didn't want to wake up. He was in their den. Safe and warm, surrounded by their scents and the scents of their pack.

"SHITTY HAIR WAKE UP!"

The stinging pain to his cheek made him jerk up with a shout.

Ruby eyes wide, fangs partially descended out of shock and chest heaving. He could still smell their den but he wasn't in the dorms.

"Calm alpha. Breath." Katsuki's voice again, but deeper, rougher.

The memories from this morning came flooding back. Villain, future, Katsuki and...himself.

His vision came into focus looking at his future mate. He really took in his features this time.

Sharp, pointed cheek bones and jaw. His skin was still pale, but there was a dusting of freckles across his nose that he wouldn't have noticed. He had taken the scent patch off and he could see the mating bite fully.

"With me Shitty Hair?"

"Ye-yeah." Kirishima's voice cracked slightly.

"Good. We were worried about you."

He looked over Katsuki's shoulder and there he was. Literally, himself.

"Hi."

Katsuki snorted, "You see yourself and that's what you say? Hi?"

Older him pouted, "Don't be mean."

Oh, that's why people said he looked like a puppy.

"Eiji."

"Yes?" They both answered.

"Fuck this is going to get confusing. Okay, you're Kirishima," Katsuki pointed to Kirishima, "And you're Eijirou." He pointed to his older self.

"Now. Eijirou remembers most of this day. It lasts 24 hours and he remembers that I picked you up and brought you here and that after 24 hours you appeared back where you were. Other then that he is useless."

"Hey! It's probably good I don't remember much from the future!"

Katsuki rolled his eyes and stood up, kissing his mate on the cheek, "I'm going to finish dinner."

He walked off leaving the two of them together.

"So..."

Kirishima shifted on the couch, moving so he was sitting instead of laying, "So..."

Eijirou gave a sheepish smile, "Any questions?"

"Um...how old...are you..."

"Oh! I'm 26, Kat is 27."

Ten years. This is what they were going to look like in ten years.

"Yeah. It's crazy right? But you'll get there. Here? I don't know, time travel is confusing."

Kirishima groaned, all this was giving him a headache.

"Come on. I want to show you something before dinner." Eijirou stood up from where he was sitting on an ottoman and gestured for him to follow.

They walked down a hall, past the kitchen where they got a good look of Katsuki's ass as he bent over to get something out of the oven, and to what looked like an office.

There were two desks, both with a laptop and various piles of paperwork.

But Kirishima was more intrigued by the wall. It was decorated with tons of newspaper and magazine covers, letters, photos and children's drawings.

"I keep every letter I get. Every picture, and headlines that talk about the people I save."

Eijirou smiled fondly at the wall, "I remember the first one I got. I cried for an hour. You're going to do great things, don't lose faith."

Kirishima felt like crying himself. He had started to notice that his classmates were pulling away from him

He felt like he was getting left behind. But knowing that this was his future? Well, it didn't make those worries go away, but he definitely felt a lot more confident.

"SHITTY HAIR ONE AND TWO! GET IN HERE!"

Eijirou rolled his eyes, "Come on. Kat's a stickler for dinner time."

Kirishima nodded, "Good to know that doesn't change then."

They went back to the kitchen where Katsuki was sitting at the dinner table stacked high with bowls of rice, grilled steaks and veggies.

They ate in relative silence. Every now and then there would be a grunt or someone asked for a plate they couldn't reach but it was mostly the sound of chop sticks and forks against plates and bowls.

After they finished eating, Katsuki brought him some old clothes so he could get out of his hero costume. The pants were okay, but the shirt was a bit big.

"Our room is down the hall if you need anything."

And they left him in his room, the guest room.

Kirishima tried to sleep. He did. But it was hard, not being with his boyfriend. They had taken to sleeping together every night.

It was around midnight when he got up with a sigh, intending to get a cup of water.

But when he got into the hallway he heard a noise.

A moan.

He knew that moan. It was Katsuki's.

And then he smelled it. Sweat and arousal.

His heart started racing and his cock immediately got hard. He didn't even realize he had moved toward the smell until he pushed against the door in front of him.

The room was big and smelled heavily of sex. But the only thing that drew his eyes was the sight of Katsuki's bare back and ass, flexing as he pounded into Eijirou below him. He was holding Eijirou's legs against his chest by his knees and feet way in the air by his head.

"Alpha! Alpha please!" Eijirou sounded so fucked out, voice cracking as he begged.

Katsuki slowed his thrusts to a grind, "We have a visitor."

He turned and looked at Kirishima in the doorway.

"Just gonna stand there gawking?"

Kirishima panted, pupils dilating till there was only a ring of red left.

"How." He was half way across the room when he noticed and smelled the wetness between Katsuki's cheeks.

Cum.

"Holy fuck." He tripped over his pants a bit as he shed them before crawling into the bed.

"Can I-"

"Kirishima. Fuck me." Katsuki let go of one of Eijirou's legs, letting it drop around his waist, to turn and pull the smaller alpha into a kiss. It was rough and completely dominated by the blond but Kirishima didn't care. They only stopped when they hear a loud whine.

Eijirou was rolling his hips against Katsuki's, trying to get his to start moving again. His lips were swollen and bitten, shiny with spit and his eyes were pooling with tears.

"Alpha!"

"Oh shush you slut. You get to enjoy this twice, I'll only get it once."

Katsuki grabbed Eijirou's cock, large knot fully inflated at the base and squeezed, making the alpha cry out.

Kirishima gulped.

"Come one baby boy, fuck your Alpha."

The blond bent over slightly, forcing his cock deeper into his mate, while presenting his wet hole.

Kirishima lined himself up and sunk in till his barely formed knot was teasing the rim.

Katsuki let out a groan, "There we go. Now fuck me."

The red head whined, high and needy, before he pulled back and slammed back inside.

"That's it. Good boy." Katsuki kept praising him, pushing back and meeting him thrust for thrust, almost ignoring the large alpha underneath him.

Kirishima knew he wasn't going to last. The smell of sex, cum and arousal was too much, the wet feel of Katsuki's hole was too much.

His knot was rapidly inflating and all he could do was keep pounding into his alpha.

"Keep going. Come on. Almost there." Katsuki reached back and grabbed his hip, forcing him to grind against his prostate as his knot fully inflated.

Kirishima rested his forehead between strong shoulder blades, shaking as his came deep inside his future mate, teeth itching to sink into corded muscle.

"Such a good boy. But now I have another good boy to take care of."

Katsuki shifted his hips and Kirishima's knot popped out.

Kirishima cried out, hands immediately clutching his pulsing cock and knots, sitting back on his ass.

"What...how...?"

"Oh baby boy. You're knot now is just a tiny thing compared to Eiji's."

Katsuki smirked over his shoulder, hips rolling into said alpha as cum leaked down his thighs.

Kirishima didn't know what was hotter. Watching Katsuki fuck his older self like a monster or watching the cum leak out of his as he did.

"Baby boy." Katsuki's voice was starting come out in pants, "Come and let Eiji clean of your dick."

Both Kirishima and Eijirou whined at the command.

Kirishima climbed around the bed, kneeling near Eijirou's head.

His mouth was wide open, tongue lolled out.

"Go on alpha, clean yourself."

Eijirou reached up and grabbed Kirishima's hips, pulling his still twitching cock into his mouth.

The smaller red head let out a sharp whine, cock still very sensitive.

"That's a pretty picture."

Too much. It was too much.

The wet slide of Eijirou's tongue against his skin, the feel of hardened fingers digging into his hips, forcing him to fuck his older self's throat. But the thing that sent him over again was the barely there sharp points of teeth against his knot.

Kirishima's eyes rolled back into his head, jaw dropped as he came for a second time as his older self's chick erupted over his chest.

Everything went black.

Kirishima woke up warm and still tired.

"There he is. Thought we'd lost you."

His eyes refocused on his own face.

Oh yeah...

OH YEAH!

"Uh...I don't-"

"Shut up. Enjoy it." Katsuki's voice breathed in his ear. He was pressed against Kirishima's back.

"Have you ever wanted to take your own knot?"

Kirishima sucked in a breath.

"Katsuki. Don't force him." Eijirou's voice was firm, but breathy.

He wanted it too.

"I know you. I know you both. You've thought about it before, and now we can actually do it."

"Please."

Kirishima barely got the word out before he was being manhandled by the larger alphas.

Up on his hands and knees, presenting himself to Eijirou behind him, while Katsuki's half hard cock rested in front of him.

"That's a good boy. Relax and let Eiji open you up." Kirishima whined, feeling a warm tongue lap it's way from his balls to his hole.

"Oh fuck!" Katsuki threaded his fingers through red hair, scratching his scalp with blunt finger nails.

While Katsuki kept him relaxed, Eijirou was opening him up. Using his tongue and fingers, stretching the ring of muscle until it was dripping in spit.

Kirishima was shaking, panting into Katsuki's thigh where he had such his teeth in a few times to stop his whines from escaping.

"Ready baby boy?"

"Please...alphas....wanna feel...."

He was breathy and babbling, canting his hips up higher trying to entice the alpha behind him.

"Deep breath."

Katsuki pulled Kirishima up out of his lap by his hair, claiming his mouth in a wet kiss while Eijirou lined up.

Kirishima moaned, high pitched and hoarse, as the head of Eijirou's thick cock popped past his rim.

"Fuck he's so tight."

The alpha bent over his back, holding onto his hips as each inch slid deeper inside.

"Relax baby." Eijirou's voice whispered in his ear.

Katsuki pulled away from his mouth, and pressed Kirishima's nose against his scent gland.

"That's it. Deep breaths."

Eijirou groaned, dragging one hand up his chest to his throat, giving it just enough of a squeeze to have the smaller red head wheeze.

"Now who's forcing."

"I know what I like Kat."

Eijirou and Katsuki were completely ignoring the boy between them, letting him continue to breath in thick alpha scent in short bursts.

They eventually started kissing, open mouthed and wet, tongues dragging against each other.

Kirishima was in a daze. He felt so full but also light. He knew he had breathed in to y much of Katsuki's scent but he didn't care.

He mouthed at the skin pressed against his face, finding enough grounding to squeeze around the thick cock inside him.

"Fuck!"

Eijirou gasped, pulling away from his mate and grinding his hips forward, "Is that your cry for attention baby?"

Katsuki gripped his hair hard, yanking him away from his scent so he could shove two fingers into his mouth, "I don't think he wants just one knot. He wants two."

Kirishima whined pathetically.

Yes! Yes he wanted both of his alpha's knots!

Eijirou returned his hands to his hips, allowing Katsuki to maneuver the small redhead back down.

"Nice and wide, there we go."

The blond fed his cock into Kirishima's mouth until his nose was buried in blond pubes.

Eijirou have no warning as he pulled back and slammed in again, making Kirishima scream around the cock in his mouth.

Katsuki moaned, "Do that again."

So he did. Over and over.

Katsuki pulled out too, holding Kirishima's head in place as he started to fuck his mouth.

Their paces didn't match, it was maddening.

Eijirou was brutal, fucking hard and fast, hips held in a bruising grip and skin rapidly turning red from abuse.

Katsuki was taking it slow, pressing forward until Kirishima was gagging only to pull out until his tongue could barely lap at the tip.

Kirishima lost track of time. He lost track of everything.

Except for the cocks fucking him and the hands touching him.

He didn't even realize that he had cum, knot fully formed and cum drooling from the tip.

He didn't come back to himself until he felt the forming knot between his teeth.

"Relax. Breath baby boy, we got you."

Mate. Alpha.

Kirishima too a deep breath through his nose as the knot locked behind his teeth, forcing him to gulp down his alphas cum as it shot down his throat.

"Almost there, almost there."

Eijirou's voice was far away, panting as he felt incredibly full. Even more then before.

A large hand came and messaged his throat, feeling the cock lodged in it.

"Knot him alpha."

Then Kirishima felt it.

So big it almost hurt but it felt so good, pressed directly against his prostate.

He felt his own cock give a weak twitch as cum flooded his insides.

"He's out again. I don't remember you passing out this much." Katsuki teased his mate, absentmindedly stroking Kirishima's hair.

Eijirou huffed, "Yeah well give him a break. He doesn't normally deal with two fully grown alphas."

The blond rolled his eyes, "Whatever you say."

After a few minutes, Katsuki's knot had gone down enough that he could pull out of Kirishima's mouth, tip still connected with a line of spit and cum.

They moved so the two redheads were laying on their sides.

"Fuck look at his stomach."

Eijirou moved Kirishima's arm and sure enough his stomach was distended, poking out in a cute way that almost reminded him of a newly pregnant omega.

"This is where you get it from!" Katsuki was snickering.

"Get what from?"

"This is why you like me stuffing you full of cum."

Eijirou opening his mouth to retort but quickly closed it. This did make a lot of sense.

Once his knot was deflated enough to slip out, the two alphas cleaned the still very much passed out Kirishima and tucked him into bed between them.

Kirishima woke up the next morning sore all over. Even his jaw hurt. He stretched and going his way to the kitchen where Katsuki was coming breakfast.

"Morning sleepy head."

Kirishima yawned, "Morning. You need to get a new guest bed. I'm really stiff."

Katsuki chuckled, "I'll look into it. Food'll be ready in a bit, grab a seat."

Eijirou was already sitting at the table, reading the newspaper and sipping a cup of coffee.

Katsuki brought the food to the table and they tuck in.

"We sent your costume down to wash. Should be ready in an hour and then we need to get you back to the wearhouse."

Kirishima blinked and scrunched his eyebrows up before remembering.

He was only in the future for 24 hours.

They finished eating and sure enough his costume was sent up by an intern.

Eijirou said his goodbyes at the apartment, with a wink and a head nod to their office.

"Don't give up."

Then they whizzed away back to where he came from on Katsuki's bike.

"So."

"So. Don't let him walk away."

"What?"

Katsuki sighed, and scratched the back of his head, "His- my brain is stupid sometimes. Says stupid things. Don't let me walk away, alright?"

Kirishima nodded, "I won't."

"Good." Katsuki surged forward and kissed him again.

"One for the road."

And then he was gone, replaced by FatGum, Suneater and his Ground Zero.

"Red! Don't scare us like that!"

Kirishima smiled, "Sorry."

Back in the future, Eijirou wrapped his arms around his mate as soon as he walked into the apartment.

"Shitty Hair. How do you not remember last night?"

"We fucked me so good that it's all just a blur."

"Damn straight we did."

"Can't wait till mini you shows up next month."

~The End