She is the mother of Judith and Michael, as well as the biological mother of Laurie Strode. She is in an abusive relationship with Ronnie White. She does not know that her son is mentally unstable, nor that Michael kills animals as a habit. She also gets called to Michael's school mutiple times due to actions.
On Halloween night in 1990 right before she goes to work, she tells her son that things will change for the better from that day forward. While working at a strip club, she misses seeing Michael killing Ronnie, Judith, and Judith's boyfriend, Steve. When she arrives home she finds Michael sitting outside with Angel in his arms. She questions what is going on and cries when she sees Judith's body. After this, Michael is put in custody. Deborah vists her son regularly and slowly sees that her son is becoming more unstable as he starts to wear masks all the time and rarely talks. At first, she is still in diselief that her son killed anyone and when he asks how everyone at home is doing, she lies to him and tells him that everything is fine, clearly trying to hold back from crying. On another visit, she brings him a toy white horse, and Michael tells her of a dream he had where she was dressed in all white and was walking down a white hallway with a white horse, telling him that she would take him home.
On her last visit, in September 1993, Deborah witnesses her son attacking a nurse and killing her. She tries to calm him down but when she takes off his mask, he snaps at her and she realizes what her son has became. When she returns home, Deborah commits suicide by shooting herself while watching old home videos of Michael.
Years later, it is shown that Michael, and later Laurie, has psychological visions of their mother and the horse.