In an alternate timeline, Romana I never travelled with the Fourth Doctor, instead living her life on Gallifrey and eventually having a child with Andred named Antonin. In this timeline, it was Leela and K9 Mark I who accompanied the Doctor on his search for the Key.
The Time Lords of this timeline sold their technologies to other races, and were capable of taking regenerations from one person and implanting them into another. (AUDIO: Reborn)