The Fourth Doctor is a natural bohemian who permanently left UNIT in order to return to a life of deep universal wandering. More so than his previous incarnations, he is thrilled by discovery and adventure. Galvanized by higher purpose, he is disarmingly loopy, brilliant and entirely serious, all at the same time. To an extent, the Fourth Doctor is the most unpredictable of his incarnations, befuddling all with his intelligence, constantly leaving others wondering if they have his full attention and using his more off the wall mannerisms against adversaries to distract them while arranging to take control of the situation. His keen judge of character also enables him to navigate his way through situations with new people, helping him to discern friend from foe. Although like all his selves he prefers his brain over his brawn, he is a capable swordsman and fighter, following on from the martial expertise of his immediate former self. He improvises non-lethal weaponry when necessary but was also not averse to more lethal weaponry as a necessity, against both sentient and non-sentient beings.
Despite his charm and offbeat humour, the Fourth Doctor is arguably more aloof and sombre than his previous incarnations. He could become intensely brooding, serious and even callous, and would keenly scrutinize his surroundings even when playing the fool. In stories such as Pyramids of Mars he is concerned that he is approaching middle age and often contemplates his outsider status. He could also be furious with those he saw as stupid, frivolous, misguided or evil. When taking charge, he could be considered authoritative to the point of egocentricity, but as it is, he is usually the only one capable of solving the situations he finds himself in. He generally maintained his distance from the Time Lords, clearly resenting that even after they had lifted his exile, they continue re-entering his life when they deemed it necessary. Not only did he seem more inclined toward a solitary existence, he also emphasized his distance from humanity, although he has stated on more than one occasion that he found mankind to be his favourite species.