James K. Flynn
The Doctor is about 1850 years old, but looks to be the Earth-equivalent of being in his 50's He is a delicate balance of fiery passion and sombre thoughtfulness. This Doctor is always at the centre of the story, pushing things forward and not in over his head. (At least not intentionally.) He's not omniscient or infallible; however, he has lived a long time now and brings all of that wisdom and experience to the table.
The Doctor realizes that there are more days behind him than ahead. This latest regeneration was very traumatic, and it will echo in this incarnation. He ponders why he thrusts himself into danger constantly, trying to save the universe or worlds from various menaces. He has lost loved ones and has lost lives of his own. This weariness has set in, wondering why he continues to do it. But when faced with each new menace or tyrant, this weariness can melt away with the strong sense of purpose. He refuses to accept casualties, he refuses to accept that he cannot catch all of the proverbial "juggling balls" that he has thrown in the air when they come down. Each loss of life is felt with this incarnation. He realizes that so much of the preciousness of life is in the little details, the minutiae that people take for granted day to day. It is in this preciousness that his fiery passion comes from.
It should not be construed in any sense that the Doctor becomes mired in self-pity or continued depression, however. This incarnation is very much at the centre of things, due to a renewed inquisitive mind, and is willing to take charge. In fact, he wouldn’t have it any other way. Think of the "Sherlock Holmes" aspects of the Doctor's personality being further emphasised. He enjoys a good mystery; in fact, subconsciously he could be using every investigation to find out more about himself, to find out why keeps doing what he does.
The Doctor can be loving in a grandfatherly way. He's not overtly fluffy or lovable, but in the little ways. He could be stern with the adults and then throw a wink a child's way when the adults aren't looking. He could be consoling a companion and surprise them with a bowl of their favourite ice cream. He takes the time to learn the little things about them, because he knows it's critical to enriching their lives.
The Doctor is not above manipulating his enemies or being involved in a master scheme against them. However, he adamantly refuses to involve innocents. This Doctor would be appalled to have taken Ace, one of his older companions, to confront her past without her knowledge. To this incarnation, it was a juvenile trick, something he did in his "youth" but is ashamed to admit now.
This Doctor is partial to reading Graham Greene. He loves the theatre and has determined to try to catch the opening nights of the most famous plays, in sequential order, if the TARDIS allows. He keeps wanting to finish "that chess match with King Richard". The Doctor considered revisiting some of his old companions, but things always keep coming up. This Doctor attends the annual "John Smith" convention held in Ohio…he figures that he ought to meet some of the genuine article. He finds punk music "interesting" but still can't understand the interest in electronic/techno