Lavi reads nonfiction, primarily history, biography, languages and encyclopedias. He's read certain classics (like Shakespeare's greats, Marlowe, Dickens, etc.), since they're classics, but doesn't voluntarily read fiction. He's also read Plato and Aristotle, but could care less about philosophy.
C.C. reads whatever catches her attention. She likes mystery stories, I think. She also reads fashion and cosplay/gothloli magazines and gossip columns. X3
Kamui... doesn't really read. Though he might be reading/have read a "how to take care of your kitten" book after getting May. If you were to put a book of photographs (like one of those coffee table books) in front of him, he might be interested for a little while.