My parents, your grandparents, they put it here when it became clear that the police weren't gonna find my body. They visit every week and they bring flowers even though there's no one buried here. The Isobel they knew is dead. So maybe there's a part of me that's buried here. The human part. The part that I abandoned when I chose to become a vampire. The part that used to dream about the day that she'd know her daughter.
Isobel to Elena

Know Thy Enemy is the seventeenth episode of the second season of The Vampire Diaries and the thirty-ninth episode of the series overall.


HIDE IN PLAIN SIGHTElena and Alaric both lash out at John when Isobel’s unexpected arrival leaves Jenna devastated. Bonnie works with Damon and Jeremy to find the spell they’ll need to harness her ancestors’ power. A heartbroken Caroline doesn’t know what to do about Matt. Stefan and Damon realize they have a new secret weapon.    



Main Cast

Recurring Cast



  • Antagonist: Klaus
  • First appearance of Klaus, though only while possessing Alaric's body.
  • Hilariously, Damon is revealed to have a closet full of black leather jackets.
  • Isobel and John reveals to Stefan and Elena that the reason that they burned all the tomb vampires was to prevent them from spreading the word that Katherine was still alive. They knew of Klaus' obsession with finding Katherine and wanted to keep him out of Mystic Falls in order to protect Elena.
    • This is the first episode to show a vampire being killed by sunlight exposure (Isobel).
    • Isobel dies in this episode, making her the second character whose name is also an episode title to die, after Rose.
  • This is the first time we see a lapis lazuli daylight ring be temporarily deactivated by magic.
  • This is also the first time that a character is possessed by the spirit of another living/undead person due to the use of a witch's spell.
  • The name of the episode was revealed on Valentine's Day by Ian Somerhalder.[1]
  • This episode has only two songs on the soundtrack, making it an episode of the series with the least songs featured.
  • This is the first episode where Katerina Graham is credited as Kat Graham.
  • Matt Davis becomes the second main cast member to have a dual role, after Nina Dobrev.
  • There are five recurring characters from Season One that reappear in this episode. They are as follows: Isobel Flemming, John Gilbert, Elizabeth Forbes, Frank, and Carol Lockwood.
  • 'Zdravei', which Klaus (in Alaric's body) said to Katherine means 'Hello' in Bulgarian.


Body Count

  • Isobel - Suicide/self-immolation in sunlight as a result of Klaus' compulsion.

Cultural References

  • "Know your enemy" is a saying derived from Sun Tzu's The Art of War.
  • "Know Thy Enemy" is a 2009 hip-hop drama movie.

Behind the Scenes

  • This episode had about 2.73 million viewers in USA, which was 0.26 million less than the previous episode.


Stefan: "Why don't you call Alaric and let him know that his wife just showed up on his girlfriend's doorstep?"

Damon: [to Katherine] "Don’t mistake the fact that we haven’t set you on fire in your sleep for trust."

Damon: [to Bonnie and Jeremy] "Great, we’ll have to put that on our list of things to do today-- harness dead witch power."

Elena: "You screw up everything, John. Everything you touch just falls apart. But, you’re the only parent I have left. So, maybe I can learn not to hate you."

Klaus [in Alaric's body]: Bulgarian: "Здравей, Катерина! / Zdravei, Katerina!" English: "Hello, Katherine!"

Elena [about Isobel]: "If that’s what you thought of her, then why did you ever put your trust in her at all?"
John: "Because I was there when she gave birth to you, Elena. I saw how heartbroken she was to give you up. And, because she was the first girl I ever loved. And, when she said she’d help keep you safe, I believed her."

John [about Isobel]: "I always knew that she and Katherine were close, but I never realized that Isobel and her were working against me. Two of the world’s most uncaring and selfish vampires, and yet they were genuinely friends."

Caroline [about Matt to Elena]: "You know, this wasn’t how it was supposed to happen. I was supposed to tell him at the right moment, in the right way, and he was supposed to be okay with it because he loves me."



Last.fm_play.png "Give Me Strength" – Snow Patrol
Last.fm_play.png "Halfway Gone" – Piano Tribute Players



See also

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