DS6 prefers non-fiction. One exception is the Geronimo Stilton series, which he loves. He is also one who gets very upset with the inevitable tension in fiction - whether it's kids behaving badly (as in most boys' fiction series) or parents or animals getting sick or injured or dying. I don't know why it's so hard to find good fiction for boys that is not too upsetting. But it just appears to be the case for DS.