Larna

Larna was one of the Doctor's best students at the Academy when he taught on Gallifrey.

Biography
Larna developed a relationship with the Doctor during her time at the Academy and commited suicide with a knife to try and stop the Doctor leaving for the Station. She was later resurrected by Omega at the Doctor's request. Larna the set off to tidy up the “side-effects” from an incident which caused history to change. (PDA: The Infinity Doctors)

Larna once travelled back in time and associated herself with the Doctor's parents, Ulysses and Penelope Gate and told them that she was from their planets future. She gave the High Council a prophecy that told of Gallifrey falling after a number of attacks from different species, and that one single Time Lord would have a hand in all of those events. (EDA: The Gallifrey Chronicles)

Larna later worked for the Doctor's father in Berkeley, San Francisco in 2002 on the Advanced Research Project. (EDA: Unnatural History)