I could never be or have been J.K. Rowling or Stephanie Meyer, because it honestly would never occur to me to write a novel about teenage wizards or vampires. Not having completely sold out on my early ideals (yet, give it time) I try to make each novel different, and as far as I'm concerned everything that can be said or done about either genre has been said and done. What I've read of Rowling and heard of Meyer only confirms this opinion.
I will admit this could potentially backfire because it means I could never have written John Ajvide Lindqvist's Låt Den Rätte Komma In / Let the Right One In either, which is a vampire novel and a bloody good one and everyone ought to read it. Or failing that, watch the movie, which I've just done and which sticks pretty close to the book though loses some of the subplots and depth.
Not that it particularly says anything new - it owes too much to Interview with the Vampire for that - but it says it very well. Much more Ingmar Bergman than Neil Jordan. That novel featured Claudia, a little girl who was vampirised at an early age and thus fated to be a child-shaped immortal with a taste for blood. It followed the consequences of this idea through with remorseless logic. Similar set-up here, except that even as a human Claudia was a brat, and Eli is actually quite pleasant. Yes, innocent people must die to feed Eli's unfortunate habit, because if s/he (the gender is ambiguous in the novel, less so in the movie) takes any nutrition from source then the source must be killed or become vampirised themselves. Eli didn't ask to be made into a blood sucking monster, but since that is the hand that fate has dealt ... The logic is followed through just as remorselessly, but because Eli is fundamentally sympathetic, the triumph of the novel and film is that we understand. We're rooting for Eli.
It's satisfyingly bleak and Swedish and so we can thank our lucky stars Hollywood never picked it up. In fact, Hollywood couldn't pick it up. Hollywood simply could not produce a movie which climaxes with a gang of twelve-year-old bullies being dismembered. The vampire would have to pay for it. Or, the bullies would have had to have done something truly evil to deserve their fate. Or at the very least, make them older. No, they're just bullies, faces cherubic and voices unbroken, and no, the vampire doesn't pay for it.
Eli does it because she's protecting her friend, Oskar, a lonely, alienated boy of 12. And Oskar would rather go along with a creature who can't help the fact that people must die for her to live, rather than the human bullies who may be small children but were there entirely by choice.
And, being 12, Oskar can't help pushing his luck, like deliberately making Eli demonstrate exactly what happens if you do enter without permission.
I've barely begun to scratch the surface. Read Roger Ebert's review, and either watch the movie for the story-lite (e.g. missing out on exactly how Eli became a vampire, and her relationship with the man she lives with who gets her blood) or, best of all, read the book.