|Affiliation||Johnny D.'s gang (formerly)|
|Family||Martha Thornhill (mother)|
|First Appearance||"Undercover Mother"|
|Last Appearance||"Surrendering Noah"|
Ariel was born the daughter of Martha Thornhill in Calgary, Alberta, Canada, where she was raised. When she was thirteen years old, she was sold into prostitution by her mother's boyfriend, Brian Marks, and ended up in Johnny D.'s sex trafficking ring. She was raped repeatedly for the following three years as she traveled from Toronto to Minneapolis to Buffalo and finally to New York, where she was sold to a pimp named Timmer. She befriended fellow sex slave Nina Soren and they were about to be bought by Martha, who was posing as a madam. Nina gave Ariel a phone Martha gave her and later called her, begging her to get her out. Timmer walked in on the conversation and beat Ariel severely, then sold her the next morning for $800 to Johnny himself to teach her some respect. Johnny imprisoned her and three other girls in the basement of an abandoned hospital in Queens. Ariel was then brutally raped by Johnny and four of his pimps for a week to break her.
When Timmer called Johnny to specifically request Ariel for a Super Bowl party, he drives her there himself and sends his number two, Bishop, to scout the place. When Johnny sees the cops outside the house, he pushes Ariel against the glass of his car and demands to know if she set him, but she desperately replies she didn't. Ariel is taken back to Johnny's lair and is later taken hostage by him when the police raid it. Johnny tries to escape out the backdoor, but the police catch up to him. Cornored, he grabs a piece of glass and holds it to Ariel's throat. She is eventually released and the police take her to the hospital, where she has a tearful reunion with her mother. They head home to Canada until Ariel has to testify against Johnny. (SVU: "Undercover Mother")
When Johnny's trial begins, Ariel and her mother Martha travel back to the U.S. and they are greeted by Sergeant Olivia Benson. When several witnesses against Johnny are either killed, deemed unreliable, and lie on the stand, Benson approaches Ariel, who agrees to help convince the girls to testify after she gives her the "Fearlessness" necklace that she wears all of the time. After Benson explains the situation to the other four girls, Ariel tells them about her own dealings with Johnny. Ariel then preaches that every one of them is free and Johnny cannot control them anymore, then makes them all promise to tell the truth on the stand. True to their word, all of the girls, including Ariel, successfully testify against Johnny. During Ariel's testimony, Johnny's attorney, Evan Braun, attempts to ask questions implying she ran away, but Ariel clarifies that she was kidnapped. Braun counters that the kidnapper was not Johnny and Ariel confirms this. When he asks how long she worked for him, she again clarifies for him and says Johnny held her prisoner. Braun then asks Ariel if Benson manipulated or pressured her into testifying. Ariel replies that she wanted to testify on her own volition because Johnny repeatedly raped her. When several victims in denial falsely claim she is lying, Judge Elana Barth orders the entire gallery to be removed. Ariel then witnesses Johnny flip a table over, grab a gun, and shoot several people, which eventually ends with Johnny's death. Benson asks Ariel if she is okay, and she assures her that she is relatively fine. After the trial, Ariel and Martha return home. (SVU: "Surrendering Noah")