Tenth Doctor

Biography
The Tenth Doctor came into existence after the Ninth Doctor absorbed all the energy of the Time Vortex, an act which began destroying every cell in his body, triggering a regeneration. He spent most of his time sleeping during the events of the Sycorax invasion of Earth while recovering from his regeneration. He is somewhat similar looking to David Campbell, the man that Susan fell in love with.

Characteristics
Like his predecessor, the Tenth Doctor is capable of boundless enthusiasm, though in his case often at inappropriate times. He retains and even exceeds the Ninth Doctor's capacity for righteous anger, especially when Rose is threatened, though he is more guarded when speaking of their future together. While he seems to have resolved the survivor guilt felt by the Ninth Doctor, the Tenth is is beginning to feel his age and, behind the outward playfulness, he feels a deep loneliness. His keen sense of loss leads him to empathise with those who have also suffered.

Perhaps as a side effect of the neural implosion he suffered during his regeneration, he is often confused, catching himself behaving in ways that he didn't expect. In particular, while many Doctors have intentionally flouted social conventions, the Tenth seems to be genuinely surprised when he is rude or uncouth. He is much more hooked into popular culture than his prior incarnations, particularly that of the twenty-first century, though he also has a liking for earlier rock and roll.

Personality
The Tenth Doctor is a study in contrasts. He's charismatic and slightly manic, possessing a disarming sense of humour borne of his seemingly boundless energy. He's also staunchly heroic, leaping into the fray like a slightly demented Errol Flynn. But there is an undeniable shadow cast over the jollity of the Tenth Doctor. He is not a man to be crossed heedlessly; when driven to anger, he will act without hesitation to strike down those who oppose him. His ruthlessness, bordering on arrogance, is almost eerie to behold. Beneath his youthful veneer, the Tenth Doctor is a very old man who has seen many terrible things; and in some matters, his patience has worn out. His usual jolly demeanor has somewhat disappeared since the departure of Rose. In The Runaway Bride and in trailers for Season 3, he is a little angrier, darker, and is not as friendly towards Donna and Martha. This suggests that he never really got over the "death" of Rose.

Habits and Quirks
The Tenth Doctor makes frequent reference to twentieth century pop culture, from catchphrases to allusions to television programs. He's fond of rock and roll, trying to take Rose to see both Elvis and Ian Drury, and dresses in the manner of an indie Brit-pop artist. His reading glasses match his current style.

He often remarks that exotic technology or life is "beautiful" and is genuinely enthralled by such discoveries, sometimes to the extent that he places himself or Rose in danger.

While he continues the Ninth Doctor's habits of mildy abusing both Mickey and Jackie, he generally does so in a more obviously playful fashion.

The Tenth Doctor briefly commented to Rose in "Fear Her" that he was "a dad once", but changed the subject before elaborating more. This might be a reference to Susan Foreman, the First Doctor's "grandaughter". It was never explained how Susan was the Doctor's grandaughter, who the Doctor's child (Susan's parent) was the mother of the Doctor's child was. Even from the brief mention of being a father by the Tenth Doctor in "Fear Her", we still have no idea if the Doctor had a biological child or if he was an adoptive father.