Know Thy Enemy
Know Thy Enemy is the seventeenth episode of the second season.
Written by: Mike Daniels
Directed by: Wendey Stanzler
Original Air Date: 04/07/11
Picking up immediately where the previous episode left off, Isobel is standing in the doorway as Jenna contemplates what this means, and Elena slams the door in Isobel's face. Jenna is incredibly hurt by the fact that Elena--and Alaric and John--knew that Isobel was still alive. She rushes up to her room and locks herself inside as Elena tearfully tries to apologize outside. Elena calls Damon and Stefan and tells them, and Katherine says not to let Isobel know that she's out of the tomb.
Alaric comes by and Jenna leaves, telling him and Elena that she's going to stay on campus while she works on her thesis. John talks down to Alaric and Alaric punches him and leaves. Caroline tells Stefan about Matt now knowing she's a vampire. John asks Stefan and Elena to come downstairs and they find Isobel inside. She says she's been trying to find Klaus, but hasn't been able to. She has, however, heard rumors of a doppelganger, which means others know about Elena's existence. John says that the biggest reason they got rid of the tomb vampires was to prevent them from spreading the truth about Katherine being alive, which would lead Klaus to Mystic Falls.
Isobel offers to take Elena to a house she's put in Elena's name so that only vampires she invites inside can come in. Elena tells her to leave. Damon, Bonnie, and Jeremy go to the Martin residence. Damon takes care of Luka's body while Bonnie is interested in the grimoires. She's looking for the spell to harness the powers of the dead witches. Isobel heads to the house she's staying at and finds Katherine inside. Isobel tells her that she made a deal with someone close to Klaus to save Katherine's life, and they celebrate. Isobel mentions needing the moonstone and Katherine says she can get it. She asks Damon where it is but he won't tell her. Elena and Stefan go to the Lockwood mansion so that Elena can accept something Jenna was supposed to get. Caroline is there, still looking around for Matt.
Damon takes Jeremy and Bonnie to the spot of the dead witches. When Damon enters the house, however, the witches render his daylight ring useless and he's forced to wait outside. Katherine searches for the moonstone and eventually finds it in a soap dish in Damon's bathroom. Isobel confronts Alaric and tells him how much she used to love him. Suddenly a warlock, Maddox, incapacitates him from behind. Bonnie and Jeremy go into the basement and she starts hearing voices and feeling the presence of the witches. At the Lockwood mansion, Isobel bites and kills John while Elena is giving a speech in front of a group of people. Everyone is distracted and suddenly Katherine, wearing the same outfit as Elena, grabs her. Stefan leaves with her as she calls Damon to tell him about John. As they get to Elena's car, Katherine stabs Stefan, temporarily incapacitating him. She then takes off in Elena's car.
Bonnie screams, seemingly in pain. When she comes out of it, she's weak. Damon arrives and tells Liz and Carol about John's ring. Damon takes his body. When Liz goes outside, she's confronted by Matt and he says he knows Vicki was killed by a vampire. Damon gets home and cleans himself up after carrying John's body there. He gets a call from Stefan and checks the soap dish to find the moonstone missing. Katherine goes to Isobel's house when she gets a call from Isobel, who's in a car with a near unconscious Elena. Isobel apologizes to Katherine and says she had to do it. Maddox appears and knocks Katherine out with magic.
When Caroline gets home, she finds Matt there, brought there by Liz. Matt asks Caroline to tell him more. Bonnie tells Jeremy that the witches simply told her to be careful with the immense power she can now channel. She shows it off to Jeremy by manipulating the weather. Damon and Stefan find the house Isobel was at and finds no one there. Isobel takes Elena to a cemetery where her grave is. She talks about how her parents still visit the grave and how part of her always wished to meet her daughter. Maddox calls Isobel and tells her that she's done and can let Elena go. Isobel apologizes for the version of herself that Elena has had to meet. She then tears off her necklace and burns to death in the sun.
Caroline finishes telling Matt everything and he asks her to compel him to forget. Damon and Stefan take a page out of Isobel's book and they put the deed of their mansion in Elena's name. When she signs it, she'll have control over which vampires can enter. John wakes up and apologizes, saying he didn't know what was going to happen. While reading a grimoire, Jeremy realizes that Bonnie will have to die in order to kill Klaus. She's willing to do it anyway. Matt leaves Caroline's house and then enters a car with Liz. He says he drank vervain like she told him to and got Caroline to give him the full story. Liz asks him to tell her all of it.
John tells Elena that he always hoped that Isobel still had some humanity in her and wanted to believe that she would help keep Elena safe. John is willing to leave but Elena tells him to stay and that she'll try not to hate him. Damon and Stefan discuss the fact that they're the only ones who know about Bonnie being their secret weapon. Katherine wakes up in Alaric's apartment as Maddox is doing a spell on him. Katherine tries to rush out of there but finds she can't leave. Alaric walks up to her and calls her Katerina, and she realizes that Klaus is now possessing Alaric's body.
Soundtrack:
Piano Tribute Players - Halfway Gone (Lifehouse Cover)
Snow Patrol - Give Me Strength