Rise of a Hero (Hilari Bell, 2005) is the second book of the YA fantasy trilogy that began with Fall of a Kingdom. It's the kind of fantasy that isn't exactly alternative history, but that flaunts rather than disguises its similarity to our world (much like Jacqueline Carey's Kushiel series or most of Guy Gavriel Kay's books). The three protagonists are from Farsala, an obvious Persian analogue, which has just been conquered by the Hrum--i.e. the Romans. After the defeat at the end of the first book, aristocratic Soraya, her half-caste half-brother Jiaan, and the peasant Kavi start to figure out how to fight back.
It's a page-turner, and if I have a little trouble believing teens like Jiaan and Kavi could become rebel leaders, well, I know it's YA. (I find Soraya's role more plausible, since I can see a 16-year-old girl having such a dogged and single-minded focus on saving what's left of her family.) I've already put the last book in the series on hold, and I recommend it for anyone who likes a good epic adventure.