Little is known about Amelia's personal life, other than she lived in Indianapolis, Indiana, and was loved by her parents, especially her father George, who nicknamed her "Mellie". In 2001, she was abducted by Michael Thompson, who took her to a home in St. Louis, Missouri, that he took from an elderly woman named Clara Riggins. There, he held her captive in the basement. Thompson renamed her to Violet, physically and sexually abused her, and tortured her. At some point, she gave birth to his two daughters, who they named Lily and Jasmine. Likely to keep her compliant, Thompson moved both girls to another home that he acquired from another client who trusted him, dubbed "The Disappearing Place", and allowed Amelia to visit them on certain occasions. Eventually, Amelia developed Stockholm syndrome and came to believe Thompson was actually her father. She assisted him in abducting two more girls, Gina Bryant and Sheila Woods, within the next eight years. All the while, she continued to be tortured and degraded by Thompson, who would then switch to a loving personality as a form of apology.
Amelia wakes up one night finding Gina trying to escape. She tells her that she will get them in a lot of trouble if she does that. Amelia then tries to stop Gina, but Gina overpowers her and knocks her out. After Gina escapes, Thompson returns home to find out what happened. Amelia apologizes for not stopping her, and Thompson tells her that they have to go. She says that Sheila is sick and they can't leave her, but Thompson tells her Sheila will slow them down and forcibly drags her out of the basement. The next day, Amelia, sitting at the back of Thompson's van while he is driving, tells him she needs to use the restroom. Thompson replies that she can use it soon, but when Amelia says she really needs to use the restroom, he stops the van and abuses her. Afterwards, Thompson apologizes for yelling and Amelia accepts it. Later, she asks about seeing Lily and Jasmine, but Thompson tells her to be quiet. Afterwards, he tells her he will be resting and repeats that she should be quiet. Later, the BAU and local police show up, having identified Thompson as the unsub. Thompson and Amelia are both alerted of the BAU's presence; Amelia asks him who they are, but he merely replies that if anyone ever found them, he will always love her. Thompson is then arrested, but Amelia backs away from Rossi when he tries to comfort her.
Later, they are both taken to the hospital and put in separate rooms. JJ and Reid enter Amelia's room and try to interrogate her, but when they ask for her real name, she doesn't respond. Instead, Amelia keeps saying that she needs "[her] daddy" and they need to go, then adds that Thompson told her about the police asking questions and lying, especially about him. Amelia becomes surprised when JJ and Reid tell her that they found Gina and Sheila, but is shocked when she finds out Sheila died. Later, JJ returns to Amelia's room, shows her a picture of herself as a child, and tells her about George and Maureen. However, Amelia denies everything by claiming her name is Violet. Then, JJ asks Amelia if Thompson got her pregnant, and with some reassurance from the agent, Amelia confirms that she was and refers to Lily and Jasmine as her sisters. JJ asks where her daughters are, and Amelia says that they are at the Disappearing Place. Though she doesn't know where it is, she says that Thompson knows and asks JJ to get him so that they can drive there. Later, when JJ returns, she brings along George and Maureen, surprising Amelia. When she doesn't remember them, George and Maureen try to help her, with George mentioning her nickname of "Mellie". This triggers a flashback about her childhood with her parents, but the flashback of Thompson telling her that he is the only one that loves her gets the best of her and she yells at her parents to get out.
Later, Hotch and Rossi bring Thompson to Amelia's room and they refuse to leave the both of them in private when Thompson requests for them to do so. Amelia apologizes to him for telling the BAU about Lily and Jasmine, and Thompson accepts her apology, surprising her. Then, he informs her that they can't go to see her daughters ever again and that they won't be together for a long time, which devastates Amelia. She asks to hug him; though Thompson says they won't let her, Hotch and Rossi allow it and the two embrace. Then, George and Maureen come into the room, which shocks Thompson, especially after Rossi introduces them to him. When he tries to tell Amelia again that he is the only one that loves her, Amelia starts to have the same flashback about her with her parents, followed by one of Thompson torturing and raping her. Realizing that Thompson was lying to her the whole time about being her father, Amelia remembers her past and her real name, much to the shock of Thompson and to the joy of George and Maureen. Then, Amelia starts to attack Thompson, prompting Hotch and Rossi to drag him out of the room. After Lily and Jasmine are rescued and reunited with their mother, Amelia is reunited with Gina and they both hug each other before sharing a pinkie promise that had been a trademark among the three girls. Amelia is last seen introducing George and Maureen to Lily and Jasmine.