Yikes, sorry for spoiling Precious' death in the second book! In my head I took it as a given that she'd die - I know that someone with AIDS can live a long life with treatment nowadays, but given Precious' financial situation and background, I always felt that as soon as she was diagnosed in "Push" that she would not live long.

They passingly reference Little Mongo once or twice, saying that Abdul's great-grandmother took care of her for a period of time. But we really never learn what became of her. On the other hand, I was pretty bored during much of "The Kid" so it is possible at some point they spelled out what happened to her but my mind was drifting then!!