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With his young looks, the Fifth Doctor expressed an interest things associated with Victorian and Edwardian England: cricket, tea, fair play, good manners, and a keen interest in science and exploration. He was also a sensitive and profusely humane incarnation who did not make himself an imposition, preferring to be honest, reserved, and honourable. However, the Fifth Doctor was also less willing to do what he thought was immoral, and became highly conflicted about what choices he could make in a crisis that were truly right. This was never more true than in relation to the safety of his companions. On the occasion that they were harmed, he would be very deeply affected. His hesitancy made him seemingly more fallible than many other incarnations, making those around him wonder if he was capable of resolving difficult situations. Nevertheless, he was one of the most overtly fearless incarnations, and frequently found himself right in the thick of battle.
Like his first two incarnations, the Fifth Doctor often travelled with multiple companions. However, his TARDIS was rarely as harmonious as those of his predecessors. Instead, he frequently found himself stuck between Tegan Jovanka's pessimism and Adric's arrogance or Turlough's antagonism. Stuck in the middle with him was usually Nyssa, by far his longest-serving companion, and the assistant with whom he travelled alone for many years. Even after he seemingly was settled on just having one companion, he and Peri Brown found another companion — a pharaoh from Egypt called Erimem — and the Doctor once again slid into the role of the oft-maligned chaperone.
When he passed, though, he was adventuring only with Peri, and it was for her that he gave his life. The two fell to spectrox toxaemia, a kind of poisoning. By deciding to deliver his limited supply of antidote only to her, he knew that his only hope for survival lay in regeneration.
Biography from the TARDIS Data Core article, licensed under CC-BY-SA
Notes for The Doctor