Responses
I would agree if the brother wasn't a jerk too. He clearly knows how to treat his brother kindly even when he was younger although he was still somewhat a jerk then too. Yet he insists on treating his brother even more poorly now that he's older? At least the blondie has a somewhat valid reason for the way he treats the MC. The MC was definitively the source of his trauma regardless of intent or the lack thereof.
At this point I think we all unanimously vote for the brother