Vampires and other mystical thngs. One of the girls has psychic powers and i'm pretty sure one of the boys is about to turn into some sort of monster... a werewolf probably. It's not your average vampire story by any stretch of the imagination. It looks like the woman who wrote Twilight was very much influenced by these books (they're quite old books now - about 7-10 years old at least).

Speaking of; if you see 'Fallen' by Lauren Kate anywhere, do not hesitate to buy it! Not for a second! It's an amazing book! I can't wait until the second one comes out!