The Sister Queens by Sophie Perinot (historical fiction)

I liked this book, the author's debut novel.  The author uses fictitious letters between the sisters to keep the story moving along, and they each go through some character development as they grow up.  With that said, I enjoy learning how much an author of historical fiction "makes up" and much of the relationship that drives the book appears to be the author's conclusions.  It doesn't ruin the book for me, though.