Vislor Turlough — more commonly known as, simply, Turlough, and who was known in his youth as Vis (AUDIO:Kiss of Death) — was a companion of the Fifth Doctor. He traveled principally alongside Tegan Jovanka, but also had a few adventures with Nyssa and Kamelion. He briefly met and saved the life of Peri Brown in Lanzarote on 8 May 1984 before leaving the Doctor’s company. He also had significant interaction with Brigadier Lethbridge-Stewart, the First Doctor and Susan Foreman. He encountered but did not speak with the Second and Third Doctors and Sarah Jane Smith. After leaving the TARDIS, he also met the Tenth Doctor and Emily Winter.
Turlough was a complex individual. His motivations were often unclear to those around him. He was for a time willingly under the influence of the Black Guardian. During this period, he tried to kill the Doctor. After overcoming the Black Guardian, he was a mostly-trusted member of the TARDIS crew, but there were still moments where his actions were questioned. It was only at the end of his time on the TARDIS that the Doctor finally discovered the truth about how Turlough ended up on Earth and why he was susceptible to the Black Guardian in the first place.
The Doctor once indicated that what made Turlough such an interesting travelling companion was that he never knew what Turlough was thinking.
Turlough was selfish, always shielding himself from blame. (TV: Mawdryn Undead) He could lie convincingly to most; some, such as Tegan Jovanka and Brigadier Lethbridge-Stewart, were not fooled. (TV: Mawdryn Undead,Terminus)
Although usually quick to retreat, Turlough was not so much a coward as a survivalist, preferring to avoid danger and situations he felt he couldn’t change. (TV: Warriors of the Deep, Resurrection of the Daleks)
Tegan did not like Turlough at first, finding him untrustworthy. She did not approve of the Doctor letting Turlough consider the Black Guardian’s offer, believing Turlough would choose the crystal. However, the Doctor was confident in Turlough’s morals. Nevertheless, Tegan often tried to persuade him to banish Turlough from the TARDIS. (TV: Terminus, Enlightenment; AUDIO: Cobwebs)
He saved a Phiadoran female to whom he was attracted from a large drop. He appeared to fall in love with Lytalia, but this was later revealed to be a complex deception on the part of the Phiadorans, as the species were currently serving as ‘hosts’ to the ruthless Vrall and had manipulated men to do their bidding even on their own. Despite this, his experience during this encounter encouraged him to take a closer look at himself and determine who he wanted to be compared to his past actions (PROSE: Imperial Moon).
Despite the Black Guardian’s attempts to vilify the Doctor, he recognised the Doctor’s good intentions. On numerous occasions, he tried to make the Black Guardian reconsider his order to kill the Time Lord. (TV:Terminus, Enlightenment) Turlough used the tranquility felt at the Eye of Orion to draw. (TV: The Five Doctors) He understood the TARDIS systems well enough to run a diagnostic (TV: The Five Doctors) and programmed the TARDIS to rescue the Doctor and Peri. (TV: Planet of Fire) The Doctor once compared Turlough and Tegan to bickering siblings. (AUDIO: Freakshow)