Can’t Find A Movie

I can’t remember this one movie I saw years ago..

It was about these brothers and I think one is returning to their childhood home while the other has been caring for it. The brother who has been taking care of the house has multiple personalities and each one was taking care of a different job to take care of the house. One was a nerd who helped people with accounting or tutoring or other things, one was a child who worked at a diner, one was mute (I only remember his name which was Boris), and another was a greaser. The greaser kills off the nerd personality which was kind of like the one in control and resumes control himself. The greaser tries to kill the brother, and I can’t remember if he succeeds or not.

I think the disorder in the brother stemmed from the abuse of their father after the brothers witnessed the death of their little sister.

I think I remember the scenes with the personalities always being in black and white.

I know it’s not much to go off of, but I hope that someone might be able to help me.