Can someone please explain what Jian, Jitaes brother wants? Is he good or bad...

I guess he just wants to live his life, but he is forced to keep an eye on Jitae and bring him down. Also he is like a half-blood kid in the family, so they don't treat him as part of the family which makes him go crazy (like taking drugs, going to orgys etc, and Hajoon takes advantage of it)

I thought so too and it looks like he is also trying to mess with the mom's plans? I hope he isn't a threat to Jitae