Luke makes his first appearance in While You Were Sleeping. He already knew "Elena" when meeting at the Bitter Ball. Elena nearly turns him into a vampire but compels him to forget everything that happened and to go get Bonnie. It is revealed that Liv Parker is his sister.
In Rescue Me, he is told by Bonnie that a witch named Hazel has died and he later tells Liv, as their coven was involved in protecting the doppelgangers from the Travelers. He is also seen being reluctant to form an alliance with Jeremy Gilbert, Matt Donovan, and Tyler Lockwood.
In Resident Evil, he came over to the Salvatore house to explain about Elena and Stefan's fantasy visions.In Man on Fire, he is held hostage by members of the college rugby team compelled by Enzo to get Liv to assist him by using her magic on Stefan and Elena.
In What Lies Beneath, he is first seen attempting to do a locator spell to find Enzo for Damon, both being unaware that the vampire is now dead. When Tyler arrives with information that the Travelers were planning on abducting the Doppelgängers, Damon suggests Luke do a cloaking spell to shield them from the Travelers while they hide in Bill Forbes' cabin. While the others are playing charades and "Never Have I Ever" inside, Luke is in a trance out on the front porch, casting the cloaking spell, until he is taken by Enzo. He is taken to the wood shed and tied up, the shed being set on fire when Damon and Stefan go to find him.
At the end of the episode, Luke is seen talking to Stefan, remarking upon how Stefan and his friends care about each other, while Luke's family is more about duty, which is why Luke agreed not to kill Stefan and Elena to thwart the Travelers.In Promised Land, Luke meets Liv at a diner where he's scolded for allowing the Travelers to take the doppelgängers, both by his sister and then more severely by his coven, who attacked him with magic from a distance, causing him extreme pain. Luke than teams up with his twin to kill the doppelgängers and end the spell to destroy all Spirit Magic. The two witches crash the truck carrying Elena and Stefan, killing the Traveler Maria. Liv used her power to take down Elena while Luke did the same to Stefan, until the Traveler's spell caught up with them and took away their power, allowing Stefan and Elena to flee.
In Home, Luke and his sister are driving out of town, running from the people they tried to kill. While Liv gets annoyed with Luke for his slow driving, their path on the road is blocked by Elena. When they try to reverse, they find Caroline behind them, the two vampires using their own tricks against them. Liv and Luke exit the car and are confronted by the vampires, who reveal that Stefan is dead. Despite actually being sorry, the twin refuse to help them with the resurrection spell they've got planned. To motivate her, Caroline snaps Luke's neck, giving her an incentive to perform the spell. Luke can be seen later, behind his sister as she cries and prepares the spell, with him offering support and telling her she could do it, even though she couldn't hear him.
Later, when the spell has started and after all the Travelers have passed through Bonnie, Luke was the first to cross over after Bonnie refused to call off the spell even though Liv was dying. He rushed to his sister and tried to stop her, only for her to tell him she promised to help the others. With each new person resurrected Liv got worse, to the point that Luke ignored her and forcibly stopped the spell with a spell of his own, leaving Damon trapped on the crumbling Other Side. When Elena went to see what had happened, it was revealed that Luke had taken his sister and fled the crypt.
Luke is described as very sarcastic but also very protective of his twin sister, Liv. Unlike his sister, Luke seems to have a more compassionate nature and a more liberal attitude towards vampires. Luke has often demonstrated his benevolent nature when on several occasions he has neglected to kill Elena and Stefan despite the punishment he would face from his coven. Although his sister Liv is also a very kindhearted witch with a sympathetic attitude towards vampires; unlike Luke, Liv is much less compassionate towards vampires and much more loyal to her coven.
Luke is handsome, with blue eyes and blond hair. He is of medium height with a lean and athletic build.
Luke is of Greek origin, and the meaning can be "from Lucanus or Light".
- Because Luke and his sister Liv were sent by their coven to stop the Travelers from breaking the curse, they could possibly be descended or related to the witches who originally placed the curse on the Travelers.
- He is the second LGBT character who appeared in The Vampire Diaries after Bill Forbes.
- Both Hayley Kiyoko and Chris Brochu have a role in Lemonade Mouth movie.
- He is younger than Liv by five minutes.
- He is powerful enough to perform a locator spell to locate someone any where around the world, provided they're not dead, through this establishes his strength in magic as Bonnie had difficulty performing a locator spell when practicing traditional magic.
- As stated by Liv, Liv (and assuming Luke as well) had already learnt a locator spell by grade 1 (age 6-7).
- The cloaking spell he performed to hide Stefan and Elena from the Travelers appears to be the same spell the witch Hazel used to hide Tom Avery.
- He seems to be the more compassionate twin.
- He briefly died in the episode Home, after Caroline snapped his neck. But he was ressurected by Liv.
- He might return for season six.