Talin

 was the leader in the Hypernet relay station on K4067 in the 52nd century. She asked Brabbeko to go after Hex. She observed the Seventh Doctor and Ace coming out of the TARDIS she locked down the base. She wanted to use the Doctor's knowledge to help defeat the Nucleus. She helped the Doctor and Ace to gain access to the Hypernet, and altered the code to the game they were in to aid their progress. She later tricked the Nucleus into thinking she was infected, and downloaded the Doctor and Ace back from the Nucleus. (AUDIO: Revenge of the Swarm)