he didn't her parents make her hide her truth self before he was born so he never know how terrify his sister maybe
The parents mentioned he knows how she really is!!!
Maybe that is the reason he did what he did, he wanted to have the uperhand!!!
According to the LN/WN, he was so traumatized by what she did to him that he lost all memory of it.
Hahaha!he dig he's own grave you deserved that doing that to her!
....RIP to her brother....Boy, you lived with her and you know how terrifying she is. So why did you go against her?