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Notice how he had no idea who was the person that got captured, but as soon as he saw Kacchan's face he immediately ran to him without even thinking of what he was doing (Don't get me wrong, I believe that even if this wasn't Kacchan he'd still go save them but still)
After that, Kacchan obviously wasn't happy about that. Imo at that moment he was thinking about Deku's self-sacrificing nature, he went to save him even though he knew that he wouldn't be able to do much and that's probably what scared Kacchan
In chapter 284 Kacchan finally admitted why he bullied Deku, and said that knowing that Deku doesn't take himself into account made him want to keep him at arm's length. Everyone knows that for the longest time he thought that Deku looked down on him, and everytime
He got "saved" by him made him feel like he was being made fun of, which kinda explains his reaction here. And honestly it's really sad that he didn't think that Deku was genuine towards him
From being friends with Deku, to then bullying him because he thought he was looking down on him, to then venting out his deepest insecurities to him while crying and now admitting why he bullied him and even helping him get stronger, if this isn't development and growth then
I don't know what is. I don't know what antis expected about his growth cuz he's obviously not going to change his character completely, he'll always be screaming and that's what I love him for. If you fail to see his development even now then you probably just don't care
Another thing, after he realized that Deku never looked down on him and actually admired him, his reaction to Deku fanboying over him is so funny lol
I don't know where I was going with this lol I just wanted to talk about them I guess 
