Once their mothers had gotten out all their screaming about them blowing themselves up (it was mostly the rock that got exploded, but they'd been hit with some flying shrapnel, which would scar up nicely in Katsuki's opinion), Katsuki found a good moment, got himself into his coolest pose from besides the dinning room table, and said:
"I give my explosions to the tribe. Go forth and blow shit up."
His mother smacked him over the head. His father actually did too.
Which wasn't fair. Katsuki had just given them dominance in warfare. They should be setting him up to be worshiped as Murder, King God of Explosions by future generations.
Izuku got it. He was practically jackhammering in place from excitement, even with the upper half of his head still bandaged (his mother refused to use more than the bare minimum of her healing magic as his punishment).
"So much power!" he squeaked.
"I know," said Katsuki.
"That was just a spoonful!"
"I know!"
"What if we, like, powered projectiles with it?"
"I KNOW!" Freaking guns already in the works, he was a GOD!
" You're both lucky you're not dead," said Eijio flatly.
"Tch, like the protagonist would be killed by a childhood experiment," said Katsuki with his best sneer.
He was getting very used to the dragon-face version of 'The only thing I'm impressed with is that you can be so impressed with yourself.'
Really, Katsuki didn't understand. Given Eijiro's personality, he should be the one geeking out with him instead of Izuku. Maybe this was just more evidence of Eijiro remembering being twenty-six and Izuku only having eleven years of it.
That night, however, exactly twenty-four hours after they'd bombed a hole in the cliff's scalp, he woke up with all the force of fifty more spoonfuls of their gunpowder as Izuku dropped on top of him, trembling and sobbing.
"Kacchan. Ka-kacchan."
"This better be important," he growled. His heart had nearly busted out of his chest, good god, kid.
"Kacchan," he sobbed. "You're alive, you're alive."
"...Yeah?"
"Don't you ever, EVER do that again!"
"Blow things up? Sorry, that's a no."
"Shut up!" And Izuku actually shook Katsuki against his pelt cot. "I remember what you fucking did! It was my fight, I had One for All, not you!"
Katsuki didn't know what stunned him more: Izuku using the big 'F' word or him finally remembering his past life.
Unfortunately for both of them, Izuku's wailing woke up his parents, resulting in a lit candle to reveal all the sobbing mess which was Deku sitting on top of Katsuki like he'd been about to rape him-with tears. Lots of tears.
Thankfully, he had the mind to at least try and calm down and make up an excuse to their tribe's Cheiftess and Chieftan that he'd just had a nightmare brought about by the head trauma of the explosion, because Katsuki WAS NOT going to explain past life shit with his parents who shouldn't have even followed him into this life.
When the next day came around, all gray-blue at the crack of dawn, him and Izuku spotted each other from in front of their tents at the same time and came at each other with fists to the sides, ready for a fight. The fire in Izuku's eyes and the downturn of his little eleven-year-old mouth sparked an old excitement in him. No, not that kind of excitement, you sicko.
Speaking of.
"Deku," he said.
"Kaachan," he said, equally grim. "I thought you'd grown out of that nickname?"
And, for the most part, he had. But…
"You're going back to that if you say you aren't gay," he said.
Whatever Izuku had been expecting, it hadn't been that. All fight rushed out of his system with a splutter.
"Ex-excuse me?"
"You can't say you aren't some serious masochist gay for my ass for following me into this life, you fucker," he said. "And just so you know, I like women. Women with firm, palmful titties and an ass for miles."
If he wasn't more serious about salvaging their friendship/rivalship from a multi-dimensional spanning man-crush, he'd have busted out laughing at the kaleidoscope of expressions trying to contort Izuku's face off.
"Wha-eek-gack-NO!"
"Prove it."
"What? How the hell-I'm eleven!"
"No, you sick fuck! I don't want to-" what the hell did Izuku think he was implying? "I don't care if you are gay, just whether you're gay or not for me!"
"I like Uraraka!" he squeaked. "I LOVE her!"
"THEN WHAT THE FUCK ARE YOU DOING HERE!?"
"YOU DIED FOR ME!" he screeched back. "I had to make sure you were okay wherever you went!"
"YOU ARE THE NOSIEST WORRYWART ALIVE! I CAN TAKE CARE OF MY DAMN MYSELF!"
"OBVIOUSLY NOT, AS YOU DIED!"
"SO DID YOU!"
"I WAS FIGHTING A SUPER VILLAIN!"
"SO WAS I, FUCKTARD!"
Katsuki's Mom burst out from the tent, only in her bare skinny sleepwear.
"SHUT THE FUCK UP, BRATS! PEOPLE ARE SLEEPING!"
Just past her, Katsuki spotted Eijiro's red hide huddled behind his tent, one dragon eye peeked out from around the corner. He ducked back the moment he realized Katsuki had noticed him.
"Tch," he snatched the front of Izuku's tunic. "Come on, nerd."
They had some catching up to do.
Surprise surprise, they ended up heading towards the very spot they'd just cratered the previous day-or was it two days ago now?
"So?" Katsuki growled once they cleared the edge of the village.
"So what?"
"When did you die?"
"Not long after you," Izuku grumped.
Katsuki harrumphed. That sucked. But… "Did you kill him at least?" That would be even worse unfinished business than Eijiro's if he hadn't.
He looked back to see Izuku's expression still grim, but triumphant.
"Yeah."
"Good. I'd a punched you if you hadn't, or if you were doing something stupid like feeling guilty for it."
"What? No, All for One needed to die."
"Correction, he deserved to die. Fucker was expired meat."
Izuku snorted. "For once, I agree with you."
"Shut up, you agree with me all the time." Their patched up faces evidence of that.
"In this life I do." Izuku paused. Katsuki wasn't looking at his face this time, though. He was focused on hiking up the rock trail zig-zagging up the cliff-face. "Kaachan…it's good to see you again. I'm…I'm glad we're friends."
Katsuki swallowed. "Yeah."
"Like, really. It was good to start over with you again. Really good."
"No homo."
"Oh my god, do you have to ruin everything? I already said I'm not gay! And even if I was, do you know how much of an ass you're being?"
"Not as much of an ass as you for ditching your girl before chasing after some dick you weren't even really friends with!"
"We were totally friends!"
"You call that friends? Fuck, you're screwed up, we were rivals!"
"Is that what you call Eijiro? He's following us, by the way."
Of course he was following them. "BACK OFF, LIZARD!"
" Awww," came the whine across their minds.
"Besides, how's that saying go?" He could hear Izuku's smirk and he nearly turned around to punch it right off him. "Bros before hoes?"
"Don't talk like that. It's nasty."
"What? It's how you talk."
"You ain't me, nerd. You're-ah, screw, I don't care. I lost sleep because of you, and I'm still recovering. Not all of us have super-healer witches for moms, you know."
"Hey, my mom heals you too."
"Not if my mom tells her not to."
"My point still stands."
"Sure, whatever, does this mean you're going to suck less at fighting now?"
Izuku actually paused to consider that, one hand on the cliff-wall, the other to hold a crooked finger to his lips.
"I have no idea," he muttered. "Muscle memory isn't exactly soul ingrained otherwise you wouldn't have to train as much at your age, though enough of it does remain I guess as you're still better than me, but then I was never really as naturally talented as you. Just how much of memory goes along with your soul?"
"Your muttering certainly comes along with it," Katsuki griped.
But Izuku was smiling. "Want to test it out?"
"What, the muttering?"
"No! The fighting!"
The old, evil smirk stretched across Katsuki's face like an old blanket. "Hell yes."
Long story short: Katsuki still won.
Because he was a GOD.