White come to rescue , you can come and go when you fall for someone.. he doesn't want to take his brother place but as his brother lost its authority on the gang White is the only one who can reunite and lead them with result in arising of prost among the people ,he can't return to his former life with his f demand of just he can't go to the shadow.
So Black was idealistic , believed he can upheaval society so how he became as he is now? He love his brother and want to protect him... I think he understand he lost his leadership.