My Babysitter's a Vampire 2010 ( 6.976)

Geeky 14-year old Ethan is left to babysit his younger sister, Jane, with his best friend Benny but after Ethan inadvertently puts Jane in harm's way, his parents hire a professional babysitter, the beautiful yet mysterious 17-year-old Sarah who, unbeknownst to them, is actually a fledgling vampire.