Grace O'Brien was the parental grandmother of Ryan Sinclair. She lived in Sheffield with her second husband, Graham O'Brien, whom she met during her work as a chemo nurse. Grace would often attempt to teach Ryan how to cycle, which he struggled with due to dyspraxia.
Whilst returning home after an unsuccessful session, Grace and Graham were caught when a swarm of gathering coils attacked their train in search of Karl Wright. She, along with Graham, Ryan and Yasmin Khan, would help the Doctor battle both the coil and its controller, Tzim-Sha. Grace was electrocuted whilst trying to disable the coil and fell. Mortally wounded, she died in Graham's arms. (TV: The Woman Who Fell to Earth)