A political prisoner from the planet Trion, hidden from retribution at a British private school, Vislor Turlough had a troubled beginning to his travels with the Doctor. Knocked unconscious, he came under the influence of the Black Guardian, who tasked him with killing the Doctor. Unable to fulfil this request and after trying to take his own life, Turlough rejected the Guardian and became a member of the TARDIS crew. Although loyal, he remained liable to run at the first sign of trouble. After meeting fellow Trion exiles on Sarn and learning that there was an amnesty on political prisoners, Turlough returned home with his brother Malkon.