Moira

Moira was Bill Potts' foster mother following the death of her birth mother. The two of them lived together in a flat.

Moira had no permanent partner. Neville was her ex-boyfriend and Barry was Moira's friend. (TV: The Pilot) Bill didn't like learning the names, as "I only get attached", and they were all so fleeting. (TV: Extremis) Moira was not aware that Bill was gay, and assumed she was interested in men. (TV: The Pilot, Extremis) Moira had "very strict rules about men", regarding Bill, (TV: Extremis) and told her once, "You need to keep your eye on men." (TV: The Pilot)

On Christmas 2016, Moira found pictures of Bill's birth mother in the back of a cupboard. Later, in 2017, when the flat was attacked by a sentient oil creature, Moira was with Neville again in the pub. Bill knew this because Moira called her on Neville's phone. (TV: The Pilot)

Bill moved to her own place for a while, but this soon fell through, as the house was eating her housemates, (TV: Knock Knock) and she soon returned to living with her foster mum in the interim, while in search of a new place to live. (TV: Extremis)

Shadow World
In a Shadow World simulation, Bill brought a date home, Penny, as she thought Moira would be out with Harry, who was actually named Howard. When she heard voices, Moira thought Bill had brought "some terrified man" home, and thought nothing of it once she saw Penny. She then left for the pub, telling Bill, "Don't do anything I wouldn't do," which Bill quietly doubted. (TV: Extremis)