Some time ago my younger brother mentioned on Twitter that we had come up with a theory about the young-teen novel Twilight. It actually seems to make some of the plot elements make more sense, at least to me.
Here goes... we know from throughout the book that Bella is a clumsy oaf, and quite early on she has an actual in-hospital injury after being almost hit by a car. It's also at this point that the teen vampire with the towering hair takes interest in her rather than being openly hostile. Our theory is that she was hit on the head and the whole rest of the series is in fact an hallucination. Probably brought on by actually being hit by a car, rather than being saved by some guy who has apparently been at the school for years without showing the slightest tendency towards superhuman powers. Quite similar to Life On Mars in some ways.
Before that point there is no mention of Edwward being a vampire (apart from a fairly major spoiler in the blurb) and the doings of the whole world do not revolve around Bella. After that he is a vampire and every event and characters seems to only serve the furthering of Bella's story. This is a character with nothing interesting or particularly redeeming about her, but she is very self-absorbed, so it makes complete sense that if her brain were to construct a fantasy world it would be one in which she is a central and important part; where every boy at her school seems to fancy her, and where someone would come running to save her if she jumped off a cliff.
Anyway, it's just a theory for now, and a fairly untested one as I really can't be bothered to read books 3-5 except in abbreviated form on Wikipedia. Also I'd have put all this on twitter but it would have taken quite a few messages to do so, so if all this was of no interest then sorry. I'll be back properly when I've finished the current work.