Caroline - the vampire who gave him blood - says that once he wakes up, they'll explain his options. He'll either have to drink human blood to complete the transition, or he'll die.

[Lydia swallows hard.]

If he does decide to be a vampire, she'll teach him what he needs to know. She's ... trustworthy. If he does turn, I think he'll be okay. But if he doesn't choose being a vampire, he's only going to have so much time.