Ruth Deaver is a retired professor and the estranged adoptive mother of Henry. Her fading memories may hold a key to Castle Rock, Maine's unsettling past. Ruth is in a relationship with Castle Rock's long-serving sheriff, Alan Pangborn.
Ruth Deaver was married to Castle Rock, Maine's pastor, Reverend Matthew Deaver. Ruth and Matthew tried to have a biological child, but the baby was stillborn. Instead, the couple adopted a black child, Henry. When Henry went missing for eleven days in 1991, Matthew was found half-frozen and with a broken back while out searching. He died three days later.
Ruth began suffering from a form of dementia, and Henry – who had moved to Texas – arranged for a nurse, Candace, to care for her. Candace was eventually let go, and Alan Pangborn moved in and helped to take care of Ruth. Alan took her to doctor's appointments, and helped her when the church was forced to sell a parcel of land containing Matthew Deaver's grave and move it to near Bangor, Maine.
In 2018, when Henry returned to Castle Rock, he found out about their relationship. Because of Ruth's condition, some days she seemed better than others. Alan explained to him that evenings were the worst for Ruth. When her condition led her to believe that a dog that had died the previous New Year's was still rooting through their trash, Alan dug the dog's corpse up and took a photo to prove to her it was still dead.
During Henry's stay, he invited his own son, Wendell to spend time with his grandmother. Ruth confided in Wendell about her condition, and how her memories were jumbled and she experienced them out of order. She developed a system using chess pieces to anchor her in the present. Wendell remarked that her condition was similar to a "timewalker" in his AR game whose goal was to kill their nemesis. Ruth came to believe that she had to kill her own nemesis – the Kid, who she believed was her late husband, Matthew Deaver, returned from the dead.
Ruth eventually passed away in February of 2019, and was buried next to Alan Pangborn.
In the alternate timeline, Ruth and Matthew's child was born and became the alternate Henry Deaver. Ruth and Alan were still attracted to each other, and eventually Ruth left Matthew, taking Henry with her. Alan followed her, and they lived happily. That Ruth developed Alzheimer's, leading Henry to begin studying the disease in an attempt to cure it.