Fans of the Animorphs

I think this was the best of the three books in the David trilogy. The first was leaning too much towards Idiot Plot (characters acting much dumber than we know them to be in order to advance the plot), and David's turn in the second just didn't work for me, but David as a villain works spectacularly well. There were a lot of character moments that made this overall more good than bad, and an effective turning point in the series. The ones I most remember are Jake's realization that he was an effective leader because he used others, Rachel's acceptance of the violence in her nature, and Cassie's (sadly not really followed-up on) ability to manipulate.