So my main headcanon is that Izukus dad is overseas because Izuku is quirkless, and when he found out he bounced. And I hc that Izuku knows this because he overheard his mama on the phone, and she's like "He's still young he might get his quirk." And papa Midoriya is like "Sure lemme know if that happens but for now I'm gone." and so you've got what 5 y/o Izuku knowing that it's his fault that his dad is gone and his mama is alone. And it's his fault that she cries at night because she's lonely and shit.
So then he goes to SCHOOL, and he doesn't tell anyone why his dad is gone. But people find out that he's gone and decide that yep it's because Izuku is quirkless. So they make fun of him for that not knowing that they're actually right.
And so Izuku is just fucking internalizing all this bullshit about how, no one will love him because he's quirkless, he's a burden and and obligation. And if Inko didn't feel bad for him she'd just leave.
So he's just being battered on all sides with this idea that he's useless and worthless, and then he decides that if he's useless. He's gonna try and be useful, so he puts so much of himself into being a hero and he tries to plan his life around this idea of being useful.
Here enters Bakugo (And he's been here before but now we're gonna focus on him)
So you've got Bakugo who is the person Izuku has known the longest, the one who hasn't left. And when Bakugo gets his quirk and Izuku doesn't, Bakugo tries to pull away and Izuku won't- can't lose anyone else.
So Bakugo is trying to leave for better pastures and Izuku knows he's useless, knows he's worthless but please Kacchan please don't leave. He doesn't want anyone to leave. Izuku doesn't mind the punches, the kicks, the burns, because Kacchan isn't leaving, if Kacchan's hurting him he isn't leaving and everyone leaves but his mom and Kacchan.
And Bakugo finds out that Izuku wants to be a hero? As if he won't die straight away, as if he could actually do anything, so he loses it.
And so the gross relationship that you see in the anime starts.
But if he's quiet and fast and clever, he can study heroes.
So anyway heroes, Izuku loves to watch heroes.
And if he's in a crowd then people don't know that he doesn't have a quirk, if he's surrounded by strangers they don't see that he's weak and useless and quirkless.
So he hero watches and he's good, at it, like he can work out how quirks work, strengths and weaknesses, possible uses.
If anyone asked Izuku he could tell you the strongest hero combos for nearly any type of villain, but no one asks and no one cares.
And Inko asks but he always down plays it because he doesn't want to be even more of a burden. And Izuku isn't dumb, he knows that a person without a quirk won't last long against people with them. But maybe, just maybe. He can help save someone, someone with a quirk, someone who matters.
Because at his core, Izuku thinks he doesn't matter.
So it's ok right? If he dies a hero, because at least he tried and he helped even a little. And sure maybe his mum will be sad, but if he's gone then maybe dad will come home and she won't be alone then.
And when he meets All Might, he's incandescent with joy. His hero, his Hero, and no one's ever believed in Izuku. Bakugo literally just told him to kill himself, a villain just showed him how useless he really is in a fight, so he vomits all of this onto All Might. Hoping that maybe all might will finally say;
'I believe in you,'
And All Might says....
'You can't be a hero.'
It's not a surprise, not really but still... He'd hoped, but no Izuku will never be a hero.
His mother told him, his classmates told him, and now his hero has told him.
He trudges his way home, already planning to 'grow up,' and he hears the screams. And he knows that he can't help, it's useless. He's useless.
But he goes anyway, and there's Kacchan. Choking, crying, and no one is helping him.
And it's Izuku's fault isn't it? He distracted All Might, he knocked the villain out of All Might's pocket. So he runs in, and maybe it's useless, but if he can save even one person. Isn't it enough?
So he throws his bag and grabs Kacchan and All Might saves them both, and Kacchan gets praised for 'keeping his head' and 'being brave' which is just typical. And Izuku gets yelled at because he couldn't even help someone right.
And when he finally makes his way home, exhausted and hollow, All Might shows up. Larger than life, then skinny and narrow, and he looks Izuku right in the eye. And for the first time in Izuku's life, someone looks at him with pride and wonder.
And All Might says,
"You can be a Hero."