Capaldi has said that his Doctor is "more alien than he's been in a while." He has stated that unlike his previous two incarnations who cared about humans and tried to understand them, this incarnation "doesn’t quite understand human beings or really care very much about their approval.” Jenna Coleman said of this Doctor, "He’s more removed, you can't quite access him in the same way", referring to the way you could with the more friendly accessible previous incarnation. Capaldi also specifically requested that the Doctor will not flirt with his companion the way his previous incarnation did. He has also been described as a "total adrenaline junkie". Steven Moffat has said of this Doctor, "He's a much fiercer, madder, less reliable Doctor". "He’s not as immediately approachable and he’s not necessarily looking for your approval, when he says ‘Wait here, I’ll be back’, you’re not absolutely convinced... what he’s not doing is reassuring you very much.” Mark Gatiss said that Capaldi's Doctor was "sort of Tom Baker, Jon Pertwee and even Christopher Eccleston style...it’s someone who’s not immediately going to be your best friend and can be quite abrupt and rude.” Moffat added to this analysis of the character by saying, “He has a tremendous ability with throwaway humor and a lot of it is around the fact that sometimes he is terribly rude. I think kids will think he is the rude Doctor [...] You might want to cuddle him but he really will resist.” It has been said that part of the Doctor's personality will share “a certain acid wit” of Malcolm Tucker, the role Peter Capaldi is most famous for, "specifically the attitude, the wisecracks and the energy...he can be edgy, volatile and dangerous". Capaldi has stated that all of the previous actors who had played the doctor were channeled in his portrayal and that his particular influences were Hartnell, Pertwee and Davison. He has been described as an "older, fiercer, trickier Doctor".
In spite of his darker personality, Capaldi has said that the Doctor is still, "funny, joyful, passionate, emphatic, and fearless." While Jenna Coleman added that this time, the Doctor is more "enigmatic, mysterious, complex, worn, and unmannered," when compared to his immediate two predecessors. Steven Moffat joked that he's, "more Scottish than last time."