Parable of the Talents
God damn, this book starts harsh and just keeps going. Butler takes our image of Olamina, the leader and main "good guy" from PotS, and twists it to show the darkness and megalomania. Anyone who tells you women can't write good speculative fiction or that books about mothers and daughters are chick lit needs to read this series (or maybe get beat, but that's a different story).
There's so much brutality and so little triumph in this book that I had to take it in little chunks, instead of just ripping through it the way I do with most novels. Plus, I had to keep looking behind me to make sure that the Christian fundamentalists weren't sneaking up on me.
final thought: Not as strong a novel as PotS, but put them together and you've got a true classic. I wish she'd written the third she planned.