When I was four years old, my mother became bipolar. I developed a very simple concept which helped me deal with the huge mood swings and changes in my mother's personality. I thought of her as being possessed by a bad ghost or spirit. Nothing I did could affect that evil spirit. I could only get out of her way during those times when she was possessed and became in essence another person. The rest of the time she was my real mother, fun and loving and caring.
Professionals I dealt with encouraged this view of my mother as a split personality. Although it was not medically a correct diagnosis, it completely fit my observations.
Maybe I watched too many Scooby-Doo cartoons as a kid. Hmm... that might also explain my love of goofy dogs.
The boy is now mainly dealing with grief, which is a very different issue and should be addressed specifically with grief counselling.