Rachael Peterson was the mother of Millie Peterson and aunt of Louie Rollins. She took them and the Eleventh Doctor to a theatre to see a pantomime of Peter Pan. The theatre's energy was sabotaged by a Brakari, who needed the energy for her and her baby to survive. Rachael looked over Louie as he fell weak and later unconscious, and later joined the group on the TARDIS to release the Brakari in space. (WC: Snowfall)
The next year, there was a snowstorm and wide-spread blackout caused by the Council of Dead. When the Eleventh Doctor was pulled off-course and landed near their house, Rachael demanded that he let them investigate. When the Doctor identified phosidium in the snow, Louie, the Doctor and Rachael went to the TARDIS to scan for more. At this point, Millie was kidnapped by an animated snowman and a downed cable was animated to attack them. The Doctor was able to destroy the cable, but when Rachael found out Millie was gone she was greatly upset. By tracking her with the TARDIS, they found out that she had been teleported to a factory at the other side of town and that she was likely chosen because of her connection to the Doctor. They decided to reach her on hoverboards instead of with the TARDIS. Along the way, Louie and Rachael were attacked by snowmen and teleported to the same factory. As Fasheith only needed one person as bait for the Doctor, he tried to kill Rachael. She was saved when Louie objected and Fasheith relented. Rachael was rescued after Millie returned with the TARDIS and a device to destroy the Council. (WC: Attack of the Snowmen)