They met a graduate student name Vanessa there, who at first tried to shoot Elena with an arrow because she thought she was Katherine. Upon learning the truth, Vanessa dropped some knowledge on the trio:
- Doppelgangers always hunt down those who they resemble, making it clear that Katherine has some sort of agenda that involves Elena.
- An Aztec curse created werewolves 600 years ago, relegating them to the full moon. Their natural enemy is the vampire and, according to legend, a werewolf bite can kill a vampire.
- Vanessa doesn't have much intel on Katherine, but Damon swipes a book with the name "Petrova" on it and brings it outside to Elena. Looks like he as influenced by a speech she gave about wanting to be friends and how friends don't manipulate each other. He says Katherine was from Europe and her original name was Katerina Petrova.
When this group gets home, Elena asks Damon for the truth about Jeremy and he says, no, he didn't see the ring on his finger when he snapped his neck. Elena says their friendship is over, which angers Damon because she used him on the trip to get more information on Katherine.
Also, Alaric makes out with Jenna because being down at Duke helped him get over Isobel.
Elsewhere on the episode:
- Stefan tried to help Caroline be a functioning vampire. He told her this state would heighten her personality, which means more insecurity than ever for Caroline. It also means difficulty controlling her urges, as she takes a bite out of Matt during a make out session. She and Stefan are able to compel him to forget, but Caroline realizes the danger she has placed him in. She later acts jealous about another girl and forces Matt to dump her, for his own sake, in her mind.
- We also see Mason trying to chain himself down because it's a full moon. But this doesn't work, he turns into a wolf and he escapes into the forest. He attacks Stefan and Caroline, but Tyler intervenes and screams at him to leave. Come dawn, he discovers for sure that the werewolf was Mason, when his dirty, naked uncle approaches his car and admits what he is to Tyler. Looks like these two have A LOT to discuss.
- The episode ends with Katherine standing over Caroline's bed and saying "We're gonna have so much fun together."
Source: TV Fanatic