An example of a fiction book based on history that I liked was Lucrezia Borgia by John Faunce. Got it on the clearance rack at Hastings
Lucrezia Borgia was the daughter of Pope Alexander VI. There are several rumors surounding her that has persisted through the years such as incest (sex with both her Father and brother Cesare), poisonings and murder.
This book was written as if Lucrezia was telling the story. I thought it was a very good book myself and of course for its cheap price it was even better
