My goal is destroying the gang, get rid of step father and save family. Even if mom is corrupted it's better she uses my D than someone else, put big sis under control let her know who is the man of this house. NTR is fine, it's usually a motivation since I see that gang leader i know i will never join them. Just hope author let me take revenge with pleasure.
If mc can pretend to join the gang to gather information and their flaws, mom can hate mc( because she wants him to have a normal life), little sis also hate mc but in the end final decision will determine mc is good or bad then mom and sis find out they misunderstand mc, this could be a new taste of story the fake tyrant haha.