The Fifth Doctor was the fifth incarnation of the Time Lord known as the Doctor. Appearing younger than his predecessors, the fifth incarnation expressed a new and more human side of the Doctor's alien nature.
He began his incarnation travelling with three companions, namely Adric, Nyssa, and Tegan Jovanka, all of whom had joined the TARDIS crew towards the end of his fourth incarnation. His relationship with Adric became rocky due to their lack of common interests. However, the Doctor was quite affected by Adric's death following the Cybermen's failed attack on Earth, feeling guilt for not being able to help his friend.
The Doctor took Nyssa in after the Master unintentionally destroyed Traken, giving her a home in the TARDIS. However, Nyssa departed his company when she decided to find a way to stabilise a cure for Lazar's disease.
Feeling responsible for displacing Tegan in time, the Doctor tried to return her to Heathrow Airport. After finally succeeding, Tegan changed her mind about leaving the Doctor. She was able to rejoin him thanks to a chance re-encounter between them. She ultimately parted company with the Doctor after becoming overwhelmed by the death and destruction which surrounded life in the TARDIS.
The Doctor was once again found by the Black Guardian, who sent Turlough to kill him. However, the Doctor won Turlough over and defeated the Guardian. Turlough accompanied the Doctor until his exile from Trion was lifted.
During an encounter with the Master, the Doctor gained a companion in the android Kamelion, who did not wish to harm others. However, by the time Turlough left and Peri joined, the Doctor killed Kamelion at his request as he was too weak to resist the Master's will power.
During his final adventure with Turlough and Kamelion, the Doctor unexpectedly gained Peri Brown as a companion, whom he planned to return home. However, after Turlough left and Kamelion died, the Doctor allowed Peri to travel with him for her vacation time.
Soon after, the Doctor and Peri had been exposed to unrefined Spectrox toxaemia. As there was only one dose of antidote, the Doctor decided to regenerate and give Peri the cure instead.
