#55000

since childhood, izuku has always admired katsuki’s quirk & his charismatic way of speaking & acting with no fears. the fact that he didn’t cry, that he was so brave & that he never withdrew from a battle, for izuku that was a symbol of power & admiration. needless to say, he admired katsuki for his willpower & the fact that he always wanted to win, even when things seemed impossible, just because this aspect reminded izuku about all might & his motto, which was that heroes never lose no matter what. so now, what izuku had always wanted to do & still want to accomplish, is to overcome his former friend, demonstrating that guy that he can be like him & that he can be at the same level as him, if not highter than him, showing his own power & his way of acting. this obviously always pissed katsuki & seeing someone as izuku having such ambitious aspirations, similar to his own, had turned the young nerd into an enemy for a proud & arrogant person like him. how could izuku, a quirkless boy, even thought for a single moment to become stronger than him & to overcome him ? i think this frightened him very much & made him furious. the only defense he could adopt against izuku was & is violence, physical & psychological. even during childhood, if katsuki had scared izuku to such a degree that he would start crawling to the ground without rising up again, katsuki would no longer have to worry about anything, especially of a useless quirkless like izuku who deserved nothing & that in his opinion, was clearly inferior to one of his caliber. yet this didn’t stop izuku’s will, but it only increased it. certainly those abuses have made izuku weaker & surely insecure about his power & strength, but with all might’s quirk & with the awareness that someone is believing in him & in his dream, his personality & his will had changed, turning into something much larger & powerful for izuku. this is where izuku started to change his vision & his own force while katsuki remained the same ( till the last battle these two had ) & i think this made katsuki even more pissed off with izuku. 

i want to point out that the part where izuku fails to save katsuki is to be considered as an important thing too because we are not talking about an act of FRIENDSHIP / CARING between the two heroes, less there is no feeling of friendship in izuku towards katsuki, at least not as kirishima. izuku blames himself for not being able to save katsuki because he is a hero & his code implies the fact that he would offer his life to others. izuku is an altruistic nature soul & he has always been this way & i think he will never change his way of acting & thinking of others before himself, not only because he is a hero but also because this is his personality & his own way to think. izuku then didn’t save katsuki of pure friendship but because he is a hero & an altruist guy who has failed in both of these two things & therefore he wanted to remedy it, going with his friends to save the boy’s life.

now we come to the final part, the last battle they both had, the real & first CONFRONTATION these two had. katsuki was rightly pissed off with izuku of course, but but the way the latter approached izuku let us see how katuski wants to talk & to have a real confrontation with izuku not using violence nor harsh words towards our nerd ( at first, when asking about talking with him ). the “ violence ” / “ rudeness ” that implied in his words while speaking seemed almost vanished while he was talking with izuku about his quirk & we can see how he changed his way of acting now that izuku is facing him. i want to point out that even if katsuki would avoid telling someone it, he thinks that izuku is the only one who can actually cope with his aggressive attitude & this is another reason why he would always act like he wants to kill izuku, because he himself is a sort of wall that can take his punches. that being said, katsuki is here because he wants to see what’s so incredible in izuku that all might himself saw in him. katsuki himself still seemed confused about the fact why izuku in their past, after all he had done to him, still kept following behind him, admiring him day by day, well this is a pretty simple answer to reply to. izuku as i said before kept following katsuki because the latter’s spirit & his willpower remembered those of all might & izuku himself admires this in katsuki & still admires him for it. above all these two admired the same person & this person legit built them to what they are now so it’s pretty normal seeing them acting like this in the battlefield ( supporting each other now that they cleared their feelings for each other but with the challenging sense for each other to become the greatest hero of all ).