Leah picks on Violet during her first day at Westfield High, after she sees Violet smoking in a public area. According to one of Leah's friends, Leah's grandmother died of lung cancer, so smoking is a sensitive subject for her. She continues to pick on Violet until Violet invites her to Murder House, on the promise of selling her cocaine. Violet leads Leah into the basement where Tate and the Infantata scare Leah and injure her (deep gashes in her cheek) in the process. Leah tells her parents she was mugged and files a false police report. She confides in Violet after the incident, claiming she thinks she saw the Devil in the basement. They currently spend time together to deal with their supernatural experience.
Leah is first introduced as a mean girl who continuously picks on Violet. However, after being scared and attacked in the basement of the Murder House, Leah seems to have backed off her torture of Violet at school. Her hair is also beginning to turn white as a result of her experience at the house, and Leah appears to have taken up smoking herself now.
- Pilot - Leah and Violet have a confrontation at school, which results in Violet spitting in Leah's face. Tate and the Infantata scares and injure Leah in the basement of the house.
- Home Invasion - Violet checks up on Leah at an abandoned swimming pool / skate park. Leah asks Violet if she believes in the Devil. She also confesses that her hair is turning white and she filed a fake police report about the scratch marks on her face.
- Piggy Piggy - Leah and Violet meet up in the abandoned swimming pool / skate park again. They discuss their anxiety and problems resulting from the horror of the basement. Leah has turned to the Bible, especially the apocalyptic "Book of Revelations", to make sense of her experience. She gives Violet sleeping pills with which Violet later attempts suicide.
- On Tate Langdon: "The devil is beautiful."
- To Violet Harmon: "The Devil is real and he’s not some little red man with horns and a tail. He can be beautiful because he's a fallen angel and he used to be God's favorite."
- To Violet Harmon: "In Heaven, there's this woman in labor howling in pain. And there's a red dragon with seven heads waiting so he can eat her babies. But the Archangel Michael, he hurls the dragon down to earth. From that moment on, the red dragon hates the woman, and declares war on her and all of her children. That's us."
- The actress portraying Leah, 19-year old Shelby Young, said in a "Q & A" with fans that she and Taissa had discussed Leah and Violet's relationship and decided that the two are not really friends. They do however, have no one else to talk to about the horrors of the house, since no one would believe them. They are therefore forced to spend time together to deal with their traumatic experience. Shelby likened Leah and Violet's relationship to that of siblings who do not like each other, but are stuck together.
- Shelby Young is also together with Ashley Rickards (dead cheerleader Chloe Stapleton) on MTV's Awkward.