What is the relationship between Hally and his mother in "MASTER HAROLD". . .and the boys?

In Fugard's "MASTER HAROLD". . .and the boys, the relationship between Hally and his mother is weak and seemingly distant. The audience never meets Hally's mother as a present character--she is only referenced in the telephone conversations that Hally has with her while she is at the hospital with Hally's father. But when she calls, she asks Hally to look after his father, which Hally does not want to do. Hally says that his mother allows his father to push her around, and he cannot understand why his mother does not stand up to his father. Both Hally and his mother seem to cower in the shadow of the father, and each wants the other to "solve" the problem. They do not seem to see each other as a support in dealing with the father. Hally wants his mother to be strong so that she can protect him from his father, but his mother does not appear to be in a position to do that for Hally.