The blinding light when All Might smiles in the TV screen enraptured not only Izuku but his usually uninterested bestfriend too. Kacchan is hardly phased by anything, and with anything means 𝘢𝘯𝘺 particular things that a normal kid like Izuku would be hesitating at. Flying bugs? He'll squish it without a blink. Climbing high trees? He'll climb even higher. Angry moms specially Mitsuki's hellhole wrath? He'll swat it away with an equal harsh scream of; "OLD HAG!"
Izuku can't exaggerate how much of an amazing person Kacchan is, but at least the blond is aware of it. His proud stance and snarky smirk shows enough that he is indeed happy with what he is becoming to.
A strong boy. A very, very smart kid among other peers.
And as soon as his palms can spark tiny embers, a hero he is driven to be.
"Deku will be my sidekick but that's it," he sneers, hands popping light explosion like firecracker. "I will be the best and beat All Might so your ass better not fall behind!"
"Yeah, Kacchan!" Izuku cheers along, big doe eyes sparkling at the prowess display. "I can't wait to have my quirk! Mom can take remote without her hands! Maybe I will can do the same!"
"Eh?" Katsuki shakes his head fervently, short hands flying around in protest. "That's not strong enough, Deku! I need strong sidekick, not a lame ass invisible puller!"
"Kacchan said no-no word," the greenet pouts, his red shoe digs into the sand and he finds it interesting to stare at. "Mom said Dad can breath fire. Is that strong enough, Kacchan?"
Well, at least Katsuki can sense the mood change. Izuku has his eyes downcast so he can't see much of the fiery boy's reaction. But he can hear an aggressive exhale before a not so soft pat lands on his head, "whatever, you're still a Deku."
Izuku's shoulders slump even lower, "useless?"
The hand on his head ruffles with a malice intent. To make his messier curly strands even messy. "Yeah. But that also mean you will always be with me. A Deku can't live alone, so you need me to survive!"
Just like that, Izuku energizes again. "Always together?"
"Stupid Deku," Katsuki sneers, his pearly whites teeth glints and Izuku can't be more excited for the fact that he and Kacchan will be inseparable despite anything.
The blond said so. And he never lie.
So Izuku believes him.
He always will.