My Babysitter's a Vampire S01E12 - Three Geeks and a Demon

My Babysitter's a Vampire (2011)
S01E12 Three Geeks and a Demon
Episode Overview
Ethan, Benny, and Rory perform a ritual to summon a Demon, which possesses Sarah's body, transforming her into an eccentric goth vampire with an insatiable thirst for human blood.