|“||I've dreamed of this, Tara. Dreamed of it.||”|
Little is known about Ennis's personal life, other than he ran away from home one summer. Sometime afterward, he met a teenage girl named Suzy Johnson and killed her. He then repeated the process with thirteen other girls (though he implies there could be more) before being caught by authorities and imprisoned in Virginia. Sometime in or before 2015, Ennis became the subject of several interviews with Doctor Tara Lewis, a forensic psychologist with the FBI.
At the beginning of the episode, Ennis has another interview with Lewis. In this one, he recounts the time he ran away from home and encountered Suzy Johnson. When she asks him what he felt when he was killing Suzy, he replies that he doesn't know. Lewis denies that and explains that something drove him to continue killing, but Ennis continues to insist that he doesn't know and says that it was just something he did, as "people do things every day".
At the end of the episode, after Lewis finishes up a case with the BAU, she attends another interview, which was rescheduled to an earlier date by Ennis. When she asks why he rescheduled, he taunts her, saying that he is actually the one interviewing her and not the other way around. He then asks about her fiancé, and when Lewis replies that he left, Ennis assumes that she had to choose between the both of them. However, Lewis retorts that she chose herself and continues with the interview.
Between the events of "The Night Watch" and this episode, Ennis was transferred to the serial killer wing of Virginia Supermax Prison due to a report Lewis made about her interviews with him. In 2016, a group of anarchists infiltrates the prison, planning to break out their leader Eric Rawdon. When Lewis enters the wing where Ennis is held, he recognizes her voice after a short time, greets her, and explains his transfer. She tells him that she had nothing to do with it, but Ennis doesn't believe Lewis. Meanwhile, under orders from Rawdon, Johnson opens up all of the cells in the serial killer wing.
Ennis and the other inmates surround Lewis, and one of them charges at her, but she shoots him. When Lewis tells an approaching JJ and Reid to back away from her position, Ennis misinterprets her, tells her that she can't take them all out by herself, and that backup isn't coming. Lewis tries to reason with Ennis, saying she doesn't want to hurt him and that she is trying to save his life. She then tells Ennis to look behind him; when he does, Hotch and a SWAT team breach the wing and shoot two inmates when they try to retaliate. The other serial killers, including Ennis, then surrender.
It was mentioned that Ennis would target teenage girls as his victims. Aside from that, other details about his M.O. were not disclosed.
No official profile of Ennis was made by the BAU, as he was already incarcerated at the time.
- Unspecified dates: Killed at least 14 girls within a span of at least three years. Known ones are:
- Suzy Johnson
- September 28, 2016: Tara Lewis (attempted)