Responses
SAMEEE. I think that he copied his brother a lot, because he said he couldnt remember what he thought of stuff, so I think he copied the brothers opinions, thoughts, feelings, etc. Cant wait till the next chapters!!!
I'm gonna guess the mom saying it was her fault means she was constantly comparing youngwoo with his brother. Since yw was such a model student she was proud and maybe his brother didn't as well. She might've been mounting pressure onto his brother and he was being pushed to the side in their family. Youngwoo might've been being blissfully ignorant to his bros feelings and after letting him leave the house and him dying he cant confront the fact that he didn't do more for his brother. He blames himself for the situation and letting his parents do what they did. But that's just a theory