Why not teen books? More seriously, when I started out writing City of Bones, I didn’t think of it as young adult, just as a fantasy novel. The characters simply happened to be teenagers. At some point I was approached by a publisher who was interested in the book, but they wanted me to “age up the characters” and make them adults. I toyed with the idea for a while, but I knew it wouldn’t work. I wanted to tell a story about characters at that crucial life stage just between adolescence and adulthood, where your choices determine the kind of person you’re going to be rather than reflecting who you already are.