Haemophobia

Twins Harper and Alex Greyson are the best vampire hunters in town -- mainly because they're the only ones who live in Lamstoke Woods. Of course, it may also have something to do with the fact that they themselves are half-vampire, but the main thing is definitely the lack of permanent vampire hunters in residence.
Enter the Everett family, one of the most famous families of vampire hunters of the past century. A family with an equal hatred of both full vampires and dhampirs like Harper and Alex. While the twins are desperate to keep their big secret under wraps, their new classmate Eleanor is quick to issue a challenge -- whoever can verify the most vampire defeats before the term ends wins. Alex is hesitant, but Harper is all for it. Lamstoke is their territory, after all.
As tension builds on both sides, Alex and Eleanor begin to notice things about their opponents (or more accurately their families in Alex's case). While Eleanor's training dictates that underhanded methods aren't good form, it also says that technically her opponents are just as deserving of a stake to the heart as the vampires they both aim to kill. Revealing the Greysons' big secret would change everything. And Alex's investigations prove that things aren't all they seem in the Everett family. Just one brief look into things is enough to reveal a huge secret, never mind one from a supernaturally keen-eyed individual who's determined to stay alive.
But however far back in the closet these skeletons are being kept, the prospect of blood will draw them all out in time... right?