The father bares most of the blame for what his daughter became because of his inability to actually parent. If he took the time to understand that initial situation, he’d have explained to her that it was a good thing she tried to step up for her friend, however that using violence was not the correct way to handle that situation. Just punishing bad behaviour isn’t enough if you don’t take the time make the child understand what they did wrong, why it is wrong, and what the right thing to do is. He didn’t take the time to do any of that, so Yu Wan continued to think she was in the right and being unfairly punished because Ni Chang is a “snitch”.