An alternate timeline was created when Ruby Sunday changed history by stepping on a butterfly. (TV: Space Babies [+]Russell T Davies, Doctor Who series 14 (BBC One and Disney+, 2024).)
History[]
The Fifteenth Doctor took Ruby Sunday to Earth 155 million years into the past to a region that would eventually become the American town of Green River, Wyoming. Accidentally stepping on a monarch butterfly, Ruby transformed into a reptilian humanoid version of herself named Rubathon Blue of the 57th Hemisphere Hatchlings. To revert the timeline, the Doctor reanimated the butterfly. (TV: Space Babies [+]Russell T Davies, Doctor Who series 14 (BBC One and Disney+, 2024).)
Aftermath[]
After the normal timeline was restored, Ruby didn't remember her reptilian version. The Doctor activated the butterfly compensation switch in his TARDIS to prevent the same accidents from happening in the future. (TV: Space Babies [+]Russell T Davies, Doctor Who series 14 (BBC One and Disney+, 2024).)
