By now we all know that Bakugo is only vulnerable with Deku, and that causes him a lot of distress because

A. He doesn’t want to be vulnerable with anyone ever, and B. Only having one semi healthy outlet for your feelings is going to be damaging

But I think what stresses Katsuki out the most about it is that he /likes/ it and is /drawn/ to it.

It’s not just the fact that Deku has a heroic heart that scares Katsuki, it’s not even the fact that he admires and gets jealous of it, it’s that that Deku has an effect on him

That is so much scarier because just writing it off as weird and annoying wouldn’t come easily, he admired it and it made him feel small but that’s not world ending even for Bakugo.
No, what rocked his boat is not only did he see and admire it, he wanted to be touched by it too.

He inherently trusts Deku against his will, and he’s so misguided that he distrusts that trust
Bk believes strong people only rely on themselves and here he is being drawn towards someone who is by all accounts regarded as weak themselves and-

-he felt like he was failing at something he couldn’t even name, Deku had this mysterious hero quality that everyone around them seemed ignorant to or looked down on while taking full advantage of

That would infuriate anyone, it’s like being gaslit by the universe.
He can feel how special Deku is, can see it in how treats people, in how Deku treated /him/. But everything around him tells him the opposite

Weak~Gentle
Defenseless~Non-aggressor
Push over~Gracious
Weird~Individualist
Crybaby~Compassionate
Useless~Nonconformist

Everything they called Deku wasn’t just wrong, it was a meant to mask over his best qualities

Qualities that aren’t appreciated in a conservative society

A society with expectations that Katsuki conforms to and excels at beautifully, but it’s all the stuff that small fry think makes heroes great and powerful. It’s the flashy parts of Heroism, what stuff that gets the job done.

But it’s not whats long term impactful, it’s not tide changing, it’s not what /heroes/ think make other heroes great.

Of course a child can put words to such a big idea, but what you can say and what you can feel don’t cancel each other out

And Katsuki wanted to lean into those parts of Deku, that’s how he recognized it to begin with. Because he saw greatness

Deku is someone you feel okay being vulnerable with, something a child usually wouldn’t recognize because most of them get to be vulnerable all the time.

And every adult in mha just sucks, they are all just unreasonable bad at child care, the Peanuts had more involved adults

But Katsuki was never allowed to be vulnerable, never coddled.
He’s always been good at everything, always confident in his ability to be good at everything.
He never really needed help, had already eased into self sufficiency by age 4 and no ever cared enough to offer anyway

But he couldn’t relax in that, his mom insists his praise was unearned and undeserved
(for the life of me I can not imagine saying that to anyone, let alone a child)
So he has to prove himself without a shadow of a doubt to be the best at everything

(I could on for days about the perfectionism but that’s for a different thread for a different day)

Then comes Deku, possibly the first person to ever treat him like he wasn’t completely invincible and didn’t have to be

Deku, who everyone says is weak but was the only person strong enough to not be so blind as to think someone has to earn a helping hand

Quite frankly I truly think Katsuki realized his mortality when Deku asked if he was okay

For the first time he had to take into account that he could have been /
not okay, and that if he hadn’t been Deku was the only one who would’ve cared enough to check

And for a moment he hesitated, he almost took that hand. He almost let someone else pull him up

And it scared the shit out of him, flipped his word upside down.
Only weak people need help, Deku is weak. Strong people help, Deku is the only person to ever even offer him help

I think the contradictions frightened him but not as much as not being at all surprised by them did.

(Properly stretch before we make this next reach)

When he looked up at his other friends he wasn’t surprised to not see Deku there

He also doesn’t seem too surprised to see Deku in front of him, or by his questions

It’s not until his /own/ hand moves that he seems conflicted, and /then/ upset

He sat there staring at Deku for a moment, not surprised to see him but by what he felt at seeing him

Everything around him has always told him he’s not /allowed/ to be vulnerable, so why would he /want/ to take someone’s helping hand?

Especially someone everyone/thing else tells him is weak?

Katsuki is a child that sadly doesn’t know that it’s completely normal to seek comfort from those close to us for even the smallest things, in fact we’re /supposed/ to.
Helping and being helped is the crux of humanity

Katsuki is a child that has been told his whole life that’s wrong to lean on others, that it makes you seem weak.

That’d be a lot for anyone to address, but a for child still stuck in an unsupportive family dynamic and a toxic school environment?

It’d have taken a miracle and a sense of self agency that children simply do not possess.

And because of all that he’s having to work so hard to unlearn and relearn so much, while balancing regret/guilt and his own hopes for the future

And before he could fully realize any of that, Deku, the only person he has ever trusted completely enough to be vulnerable with and cared enough about try to be a better person for, left him
and right before his birthday too

It’s okay it looks like he had good time still, he even got a fun hat