<Li> Recurring seasons: 1, 3 and 4 </Li> <Li> Guest starring season: 8 </Li> <P> Katherine Pierce, born Katerina Petrova (based on Katherine von Swartzschild from the novels), was part of a "Traveler" (or Romani) family, and was banished to England after bearing an illegitimate child . Upon meeting Klaus and Elijah, two of the original vampires, she learns that she is a Petrova doppelgänger--which means that she can be sacrificed to release Klaus' werewolf side . She tricked other vampires into turning her, thereby making her useless to Klaus, then spent 500 years running and hiding to escape his wrath . She arrives in Mystic Falls, where both Stefan and Damon Salvatore fall in love with her . She escapes the burning of vampires in the town, and gives the brothers her blood so that they both turn into vampires after being shot . Damon spends 145 years trying to free Katherine from a tomb, though she is not there when he opens it . In the last episode of season one, Katherine returns to Mystic Falls . </P> <P> During season two, she tells Damon that she has always been in love with Stefan and never truly cared for Damon . It is later discovered that her real reason for returning is to appease Klaus by giving him the new doppelgänger, the moonstone, and a vampire, witch, and werewolf . Stefan and Damon lock her in the tomb when they realize her plan, and even when the spell trapping vampires in the tomb is broken, she is compelled by Elijah to stay in . Elijah temporarily dies and Katherine is freed, but chooses to help Stefan and Damon . When Klaus comes to Mystic Falls, he kidnaps her and tortures her in Alaric's apartment . He eventually releases her, but she keeps track of Klaus and Stefan's whereabouts . When she learns that a vampire hunter named Mikael is the key to killing Klaus, she finds and awakens him, but goes back into hiding when Mikael's plan fails . </P>

Who turned katherine into a vampire in vampire diaries
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