You’re Elena and Jeremy Gilbert’s little sister, but you and Elena are bio sisters. You’re a Petrova like her. You’re not a doppelgänger though, but you look a lot like Elena. You’re 14, Jeremy’s 15, and Elena’s 17. And Klaus needs the Petrova sisters for the ritual to become a hybrid. He needs some of the youngest Petrova sister’s (you) blood for the ritual, but he needs all of the oldest Petrova sister’s (Elena) blood for the ritual so she will die. But Bonnie did a burrier spell so he can’t get you guys. He’s yelling at Bonnie to undo it.

Klaus: “Once I get the Petrova sisters you are dead!”