Lydia Martin

is Beacon Hills High's most popular female student, a member of Scott's Pack, the former love interest of both Jackson Whittemore and Aiden, she was Allison Argent's best friend, and (revealed in Season 3 episode "The Girl Who Knew Too Much") is a banshee. In Season 1, Lydia at first appears to be the archetypal spoiled high school queen bee. In reality she is surprisingly caring to her friends, befriending Allison on her first day at school. Lydia is also extremely intelligent, having a GPA exceeding 5.0. Her love interest is Jackson Whittemore, although she initially makes it apparent she is merely dating him due to his status as the school's lacrosse team captain, she is actually in love with him. At the start of the series, Lydia gives the impression of barely knowing who Scott and Stiles are, only expressing interest in Scott after he is Bitten and shows skill at lacrosse. Stiles, throughout Seasons 1 and 2, has an intense, sweet crush on Lydia, but she does not reciprocate. In the Season 1 penultimate episode "Formality", Lydia is Bitten by the Alpha Peter Hale but she neither dies nor turns.

In the beginning of Season 2, Lydia recovers, but suffers from a hallucination while in the shower and goes into a fugue state running around in the woods naked for two days. Later she doesn't remember the entire experience at all. Lydia is determined to be immune to the Kanima's venom, and thus Derek assumes she's the Kanima, although it is later revealed to be Jackson. Lydia suffers further fugue episodes and hallucinations which, along with Jackson's rejection, causes her to have emotional breakdowns. The hallucinations are caused by Peter, who planted an imprint of himself in Lydia's mind when he Bit her, possessing her to use her to return to life. As a result, she learns pieces of the supernatural events. In the Season 2 finale, Lydia selflessly faces the Kanima and coaxes it to transform back into Jackson, by holding up the house key Jackson had given her when they were together. When Jackson asks if she still loves him while he's dying, she responds that she does and embraces him when he is cured of being a Kanima and resurrected as a werewolf. By Season 3, Lydia has been brought up to speed on the supernatural, has greatly matured and has come to care deeply for Scott and Stiles. She and Jackson have parted since he moved to London and she is attempting to get over it. Lydia enters into a purely physical relationship with Aidan, initially to distract herself from Jackson, unaware he was assigned to get close to her to get leverage on Scott. Lydia displays a strange connection to the events occurring in Beacon Hills being mysteriously drawn to the locations of several of the sacrifices and occupying her time with drawing the same tree over and over again. Lydia joins forces with Stiles to figure out who is really behind the sacrifices. In Season 4, Lydia has started over with close friends in Kira and Malia. Lydia helps Malia in her schoolwork by lending her notes. She learns some notes she's lent are actually computer code she doesn't remember transcribing. She hears "the whispers", learning the computer code comprises the Dead Pool, the hit list of supernaturals in Beacon Hills as well as the first cipher key to decode the list: ALLISON. Lydia immediately works on getting the other two cypher keys, later learning from Meredith the second is AIDEN. Lydia cracks the final third of the Dead Pool but sees that Meredith is on the list. She is saddened that Meredith, "the only other banshee (she)'s ever known," has supposedly committed suicide out of fear. Lydia later learns her paternal grandmother Lorraine was also a banshee; she'd written a list of names, part of the Dead Pool code which lead her and Stiles to Eichen House.