After the Hydrax was drawn from N-Space into E-Space by the Great Vampire, Aukon ruled the "vampire planet" in E-Space as an advisor to Zargo and Camilla. The Three Who Rule kept the population of the planet in thrall for a thousand years.
Although ostensibly merely the royal councillor, Aukon had several powers unavailable to his two fellow lords. He had powers of telepathy and hypnotism, which he used to commune with the Great One and control the peasants. He also controlled a flock of bats, which he sent to attack the Fourth Doctor and Romana. Zargo and Camilla appeared to defer to his judgement, but both complained that he had withheld these additional powers from them, which he had promised to share.
Aukon wanted to sacrifice Romana and initiate Adric as a vampire at the Time of Arising. Aukon and the others died when the Doctor launched one of the scout ships into the heart of the Great Vampire. Without the link to the King, Aukon aged to death and decayed. (TV: State of Decay)