Kushiel's Saga by Jacqueline Carey

Travel to the world of Terre D'Ange through the magical books of the Kushiel's Legacy series.  The saga has been written in two sets of three books.  The first trilogy is: Kushiel's Dart, Kushiel's Avatar, and Kushiel's Chosen, and the primary character is Phedre no Delaunay. The second trilogy is:  Kushiel's Scion, Kushiel's Justice, and Kushiel's Mercy (publication upcoming in 2008), and the primary character is Imriel de la Courcel, the foster son of Phaedre.  Ms. Carey is working on a third trilogy taking place in the world of Terre D'Ange, but taking place in the future with a new set of characters. The first book, "Naamah's Kiss" comes out in June 2009.

The map of Terre D'Ange is France within Europe, and there are many medieval/early Renaissance characteristics in her books, and a lot of mature content.  Terre D'Ange is a land where Love rules, in all of it's forms, in the worship of Elua and his Companions.  "Love as thou wilt."  This is definitely not a series of books for the under 18 crowd, but the sexual content only serves to enrich an incredible storyline and amazing character development.  Be aware there is S&M, homosexual, and other sexually related themes occurring in these books.

These are the kind of books that you won't want to put down once you start reading, and each cliff-hanger will have you on the edge of your chair.