I remember one of my last shows, the Final Jeopardy! clue was something like 'These two boys' names are top 10 boys' names in the U.S., they both end with the same letter, and they're both names of Jesus' apostles.' Now, obviously that's not a knowable fact.
Dark books do appeal to kids because they have nice, sheltered lives - and they also appeal to children who are going through pretty hard times themselves.