The Sixth Doctor was an unpredictable and somewhat petulant egoist, whose garish, multicoloured attire reflected his volatile personality. He was both portentous and eloquent — even for the Doctor, of whom he saw himself as the finest incarnation yet — and his unpredictability was made even wilder by his mood swings, manic behaviour, bombastic outbursts and glib, unflappable wit. His personality also displayed occasionally fatalistic overtones.
The Sixth Doctor was almost supremely confident in his abilities and did not suffer fools gladly; he sometimes seemed to endure Peri's presence far more than he actually appreciated it, and his superiority complex applied to almost everyone he encountered. His intellect could support his ego, however, not only did his melodramatic arrogance and caustic wit eventually subside, it actually hid the fact that this incarnation retained the Doctor's strong moral sense and empathy. Underneath his blustering exterior, he was more determined than ever in his universal battles against evil, possessed of a tenacity and a thirst to do what was right that was far more visible than ever before. Despite his often unstable demeanour, he was always ready to act when necessary, and very little — even his companions — could hope to stand in his way.