Twisted Sister of Mine (Overworld Chronicles #5)

Twisted Sister of Mine (Overworld Chronicles #5)
Little Sister - Big Trouble...
Justin Slade is living on borrowed time.
The vampire curse is gnawing away at his body and sanity. Because the cure might lie in his special kind of magic, Justin goes to Arcane University in a desperate attempt to unlock his powers.
When he runs into his little sister, Ivy, he realizes this might be his chance to convince her he's not evil. Even better, she might be able to cure him if her shape-shifting protector, Bigglesworth, doesn't eat him first.