|“||Young, beautiful human Elena Gilbert, preserved in this moment indefinitely.||”|
This is the relationship between the cured vampire/human doppelgänger, Elena Gilbert and the siphoner turned vampire-witch hybrid, Kai Parker. They officially met in I Alone when Elena and Damon try to rescue Bonnie from the 1994 Prison World. However, they became separated when Bonnie left him trapped in another prison world. Kai later escaped and took his revenge on Bonnie by linking Elena and Bonnie's lives together. By linking their lives together, Elena is forced to slumber until Bonnie dies a natural death. Elena and Kai are separated permanently however when Damon beheads Kai as a vampire-witch hybrid.
Throughout The Vampire Diaries SeriesI Alone when her and Damon try to find a way to bring Bonnie back from the Prison World. Kai finds Elena and Damon at the graveyard and takes the Ascendant from Elena, and smashes it against the tree using his magic. After Elena picks up the pieces, he picks up one of the pieces on the floor and places it on her hand. Kai then immediately recites a spell and causes Elena's arm to burst into flames. Kai then crosses the border to Mystic Falls. Elena and Damon are unable to stop him and he escapes.
At the end of Christmas Through Your Eyes, Elena goes to the Salvatore Boarding House to see Damon after the antimagic border is removed, thanks to Kai. She knocks on the door and Damon answers it but is unable to see her. After he closes the door, Kai appears behind Elena and reveals that he put a cloaking spell on them. He uses a large hammer to knock Elena out.Elena wakes up to Kai talking about restaurants and cooking in Woke Up With a Monster. She asks him where she is, and he tells her that they are at the Mystic Grill. Elena asks him why she's here with him. Kai tells her how he absorbed all the magic from the Mystic Falls border and how he ran into the manager of the Mystic Grill. Kai then tells her in a humorous fashion about how he gave the manager a heart attack after he refused to let him inside the restaurant. Elena is disturbed by his story. Kai then tells Elena that he is too powerful and that he brought her with him to practice magic on. He then reveals the manager's dead body to her and she seems horrified. Later in the episode, Kai has Elena chained up at Mystic Falls High School. Kai comments on Elena and Bonnie's cheerleading pictures in the showcase, claiming that they were so innocent back then. He reveals that he's going to practice turning her blood into acid again, which is how he got Elena inside the school in the first place. Elena pleads to Kai and tells him he doesn't have to do this. Kai proceeds anyways and ends up melting her ring. Elena breaks free from the chains and rushes into a chemistry room and washes her burnt hand. Her ring is fully melted and she's very upset. Kai appears behind Elena commenting on the value of her ring. Suddenly, Elena puts her hand in the sunlight, setting it on fire and uses the gas inside the chemistry room to aim the fire at Kai. She is able to escape to another room, but Kai finally catches up to Elena and breaks her neck. Elena wakes up again and sees that Kai has tied her to vervain-soaked ropes. Elena asks Kai if he's actually cared about anyone. Kai tells her about his brother, Joey, and how they played together. He then breaks the soft moment by telling her about how he beat him to death. Kai continues to practice magic on her and carves a "K" on her cheek. As Elena prepares to leave the school with Damon and Jo, Kai catches up to them and Jo collapses from using too much magic. At the end of the episode, Kai is seen unconscious and tied up at the Salvatore Boarding House.
In The Day I Tried To Live, Kai comes to the Salvatore Boarding house. He tells Elena that ever since he merged with Luke, he's inherited all his good qualities. He also admits to crying, and wants to make everything up to Jo. He pleads for Elena to see the good in him as she did with Damon. Elena agrees and wants Kai to help bring Bonnie back in exchange. Kai uses his magic to transport Elena, Damon, and Jeremy to the Prison World to save Bonnie. However, they soon come back within minutes since he is too weak. Elena then agrees to let Kai transport Jeremy alone to the Prison World.
In I'll Wed You in the Golden Summertime, Elena gasps as she sees Kai crash Jo and Alaric's wedding and stab Jo, leaving her to be presumably dead. He performs a spell have everyone experience massive aneurysms. He then produces high frequency waves, causing all the glass around the room to break and the chandelier falls on several people, including Elena.
In I'm Thinking Of You All The While, Kai admits to putting a spell on Elena, linking her to Bonnie's life. As long as Bonnie lives, Elena will remain in under a sleeping spell.
In The Lies Will Catch Up To You, Damon takes Kai to the Salvatore crypt. This is where Elena's casket has been moved back to from upstate New York in order to get Kai to wake up Elena from the magical slumber he put her in years ago. Instead, Kai deceived Damon by siphoning the magic of his vampirism, and took both Elena in her coffin and the weapon that had the potential to kill Cade.
- Elena seemed to be well aware of who Kai was before meeting him.
- Kai and Elena didn't interact too much until Woke Up With a Monster.
- Kai used Elena as his test subject for practicing magic.
- Kai agreed to help Elena rescue Bonnie from the Prison World.
- Kai claims that Elena sees the good in bad people.
- He finds her relationship with Damon "totally revolting".
- Kai thinks that Elena has turned into an "an undead blood vacuum" and has "stopped caring about right and wrong".
- Kai compares himself to an Elena-in-reverse.
- Kai put a sleeping spell on Elena, putting her in some sort of coma until Bonnie dies.
- Kai nicknamed Elena "Crazy Pants".