Bakugou might be initially shocked. He's used to Izuku calling him 'kacchan' for so long that it's become a normal part of their relationship. So, when Izuku stops, it could throw him off balance.
One possible reason could be that Izuku has grown up and wants to have a more formal relationship with Bakugou. As they progress in their hero training and development, Izuku might feel that the childhood nickname 'kacchan' no longer suits their new, more mature dynamic.
Bakugou might react with his usual anger. He could lash out at the bullies verbally or even physically, which might make the situation worse. For example, if someone makes a snide comment, he could respond with a loud and aggressive retort.
Eventually, he might come to accept it in a grudging way. If Izuku is wearing the clothes for a good reason, like in a team - up situation where it's part of a strategy, Bakugou might tolerate it. But he'll still probably make some snarky comments about how Izuku better not ruin his clothes.
All Might would probably be one of the first to try to stop Bakugou. As Izuku's mentor and a symbol of justice in the story, he wouldn't tolerate such violence. Another could be their teacher, Aizawa. He's strict and protective of his students, so he'd surely step in.
Well, the story could take a turn where Izuku becomes more independent. He might start to shine on his own, without the shadow of Bakugou. His confidence could grow as he no longer has to deal with Bakugou's belittling.
Some characters might try to understand Deku's motives. Kirishima, who was close to Bakugou, would be angry at first but might also try to find out if there were any extenuating circumstances. However, many would be afraid of Deku, seeing him as a threat now that he has killed one of their own.
A great way to develop their relationship is through shared traumas. Maybe they both had a difficult experience during a villain attack. They could open up to each other about their fears and insecurities during that time. This vulnerability would bring them closer together. Additionally, they could participate in a hero competition together. As they face tough opponents, they encourage each other and celebrate their victories, which deepens their bond.
In this kind of fanfiction, it usually shows a build - up of tension between Bakugou and Izuku. Bakugou might have been constantly pushing Izuku's buttons with his aggressive behavior and taunting. This could lead to Izuku finally reaching his breaking point. For example, Bakugou's over - the - top insults about Izuku's abilities or his dreams might be too much for Izuku to bear. And when Izuku snaps, it could lead to a big confrontation between them, which can be a very dramatic and interesting plot point in the fanfiction.
Deku might be initially shocked. He's used to Bakugou's aggression, but an actual injury is different. He could be in pain and disbelief at first. Then, he might try to downplay it, especially if he doesn't want to cause trouble for Bakugou, because Deku is generally a very forgiving character.
I'm not sure if there is such a specific fanfic available. Fanfic topics can be quite diverse, but this one seems rather unethical in the context of the characters' relationships. You could try searching on major fanfic platforms like Archive of Our Own or FanFiction.net to see if it exists.