I know he was angry before, but the previous time we saw him he was just basically just interested (he hasn't even seen him in person yet), he even called it an excuse to kill a person, I don't think they've conveyed why he's THIS angry now (he hasn't even really shown much of an inferiority complex or anything either).
I can only assume his anger turned into obsession after he got beaten by his father, otherwise I don't think it was at a level where he'd be biting his lips hard enough to make himself bleed over.