Book 1: The Girl on the Half Shell: now you'd think that song would be Diamonds and Rust. Nope, it's all about Alan and the perfect song for him is Mumford's Broken Crown.
Book 2: The Girl of Token's and Tears: Now I can't tell you why, and the song will seem strange until you read the book, but it's William Shatner's Common People.
Book 3: The Girl of Diamonds and Rust: It's on the dark, explosive, emotional side. Everyone seems to come apart in this book, so it's Sober by Tool.
Book 4: The Girl in the Comfortable Quiet: my transitional book into a new set of characters and story, and the book that wraps up Chrissie's life, and so now, completely appropriate, Diamond's and Rust.
Then, into a new world with a new Heroine: The Girl in the Space between, and if you know Kaley it will make sense.Kaiser Chief's I Predict a Riot.