@ghostt i think you forgot he has a lot of ✧・゚: *✧・゚:* trauma✧・゚: *✧・゚:* and has been treated like that his entire ✧・゚: *✧・゚:* life✧・゚: *✧・゚:* .
Seriously though, not only has he been treated like that his entire life, the only person who didn't treat him like that dies many years ago and had very little power to help him, of course, he's a coward, being a coward was the best survival tactic in this scenario, and you can't reverse years of torment and trauma just because you got strong and look nice. Hell, it looks like he's having a ptsd response right before that girl comes.
From what i can tell, they seem to actually be some sort of friends, so he didn't beat em up out of that.