Cyrian

Cyrian was a young man who came from the asteroid Gaveston. When his spaceship crashed and he became stranded on the planet DV Acrol 8. Pursued by Cybermen, he was rescued by who took him aboard her TARDIS to become her travelling companion, though in effect he became a servant. He later learnt enough about the workings of the Rani's TARDIS in order to operate the control console. (NOTVALID: Rescue)

Behind the scenes
Cyrian was actually first introduced in the television story Dimensions in Time.

The name "Cyrian" is an edited version of the pronunciation of "Sir Ian", referencing the originally intended actor Sir Ian McKellen.