What happened between the brothers and the chairman?
Forgive me because I forgot their names but the blonde & black haired brothers were very close until Minjae was adopted.
Blondie didn't like that Black hair started to care for and pay more attention to Minjae rather than himself, so he was trying to find a way to get Minjae out of the picture.
Since Minjae's grades were low the chairman punished him by raping him, we saw in an earlier chapter how the Blondie saw it happen. He probably knew it would come to this anyways because Its implied the chairman did the same thing to Blondie a few times as well also, and I personally suspect Blondie wanted it to happen because he never helped Minjae study and encouraged Black hair to not help either.
Anyways Blondie approaches Minjae with a plan and tells him if Minjae hurts him badly then the chairman will send him somewhere far away and he'll be safe. Unbeknownst to Minjae that the Black hair is outside watching and to him it looks like Minjae attacked Blondie for no reason, so now he hates him and Minjae got sent away like Blondie wanted.
And that's basically it. Black hair brother still doesn't know the truth and thinks Blondie is someone he needs to protect.
What can i say he just has type