|“||Can't kill 'em all, can you?||”|
Born in 2002, Ellie is the daughter of LAPD Detective Matt Spicer, one of the survivors left behind by serial killer Billy Flynn. Little is known about her personal life, other than her parents were divorced and she is cared for by her paternal aunt Kristin whenever Matt is away at work.
Our Darkest Hour (Part 1)
In 2010, Billy returns to California, having read news articles about Matt and Ellie. He feels like he is responsible for the latter's existence, as she wouldn't have been born if he hadn't let Matt live. After killing a number of people in home invasions based on his earliest murders, Billy abducts Ellie and Kristin, bringing them to Matt and Kristin's old house, where he killed their parents over 25 years earlier, tricking Matt into going there as well. After assaulting and tying up Matt's present partner, Derek Morgan, Billy then forces Matt to surrender by holding Ellie hostage. Having everyone under control in the house's bedroom, Billy shoots and kills Matt execution-style and abducts Ellie, but not before Matt made Morgan promise that he will protect Ellie.
The Longest Night (Part 2)
Billy attempts to form a team with Ellie, cutting her hair shorter to disguise her from the authorities and bringing her along on his next home invasion. After he shoots the husband, he orders Ellie to go to their son's room and take him to the bedroom and go up and tie up the mother. Ellie does as she is instructed, but tells the son's brother to alert the neighbors. When Billy spots a family photo, he sees that the family has two boys instead of one and goes down to their bedroom. After learning what Ellie has done, he takes her to the house's attached garage, steals the car and drives away with her. After being contacted by JJ via the state emergency broadcast system, Billy is convinced by her to let Ellie go. After Billy committed suicide by cop, Morgan meets Ellie again, tells her that Kristin has died from the injuries she sustained after being assaulted by Billy, and comforts her.
It is shown in the episode that Ellie stayed in touch with Morgan, sending text messages to him on a daily basis, in which she wanted him to talk to her before she slept and after she wakes up. One of her texts stated that she befriended a girl named Jill and took an interest in soccer.
Morgan reveals that Ellie was placed in a foster family, her biological mother is out of the U.S. all of the time due to work. Prentiss would say she's happy for her despite having voiced her disapproval of Derek keeping in contact with Ellie.
In the episode, Ellie flees from her foster home by using her foster mother's credit card to buy a plane ticket to Virginia. Once there, she sought out Morgan and reveals that her foster family is awful. Among other things, one of the older boys kept trying to spy on her in the shower and none of the family members even noticed that she was gone. In the end, the foster parents' negligence leads to them losing custody of her. At the case's conclusion, Morgan helps Ellie reconnect with her biological mother, who has agreed to take her into her custody, and Ellie thanks him for his help.