"Jill couldn't fight a group like that. Adrian couldn't even fight a group like that, but for reasons he didn't entirely understand, he decided he wouldn't let Jill walk into it alone."

Adrian's Lost Chapter (Bloodlines, #0.5) - Richelle Mead

A nice 7 page introduction to Bloodlines, especially the current state of Adrian. Read the Vampire Academy series first, as this all takes place after it.