Tricksters Choice by Tamora Pierce

Trickster's Choice: Aly is the daughter of a master spy with the talents of one too. She is taken captive by pirates and brought to the Copper Isles, hundreds of islands one the edge of civil war between the raka, the first inhabitants and the luarin, the white people who invaded over three hundred years ago. Aly is to protect the daughters of her master's first wife for a summer. The eldest, Sarai, has a double claim to the throne. When the prince comes no one suspects that he will murder the duke. When Aly's father finds her she realizes how much she likes it in the Isles and stays.

I'm happy with Aly because she has faults; she does things wrong. In the Lioness series(the Lioness is her mother) Alanna does everything right. The plot is very good too. I liked the excerpts from Aly's letters and books a lot.