Consisting of Freedom's Gate, Freedom's Apprentice, and Freedom's Sisters by Naomi Kritzer.
(Some) Well-written characters, an engaging story... but a fairly standard plot. The author does manage to throw some twists into book three, but (is this a spoiler?) you probably won't be that surprised by what ends up happening after somewhere around chapter 5 of the first book. I thought Kritzer did a good job distinguishing the main characters, especially: they don't act or think identically, even when they are in identical situations.
This could be described as an alternate history: the setting is an ancient Greek empire that lasted, where Alexander lived to a ripe old age. Lauria is a "trusted aide" who, among along with auditing books and inspecting garrisons, hunts down escaped slaves and brings them back to her master. She believes at first that she is free, not seeing the chains that bind her.
The reason the plot is so predictable is because Lauria is such a strong, capable character.
In a way, this is a kind of standard fantasy plot, but I think it's a fairly good read. It does contain explicit rape and the casual acceptance of homosexuality that seems to have become widespread lately and sadly.