Like the Ninth Doctor, he sometimes uses a cheerful façade to mask inner emotions but he also able to rapidly switch between moods, from mania to anger to nonchalance. By switching gears suddenly when confronted, he disconcerts others enough to get his way.

While the Ninth Doctor tended to be somewhat standoffish around most humans, the Tenth is more extroverted and gregarious, quickly establishing a firmer rapport with Rose Tyler's friends and family than his predecessor ever managed. The Tenth Doctor is also fonder of mankind, and is apparently in awe of their tenacity and curiosity, a trait exhibited by his fourth incarnation. However, it has been made clear that the Doctor is, despite constant interaction with others, a lonely person deep down. He describes the ability of Time Lords to live so long as a curse, because while his human companions all someday leave him and eventually die, he continues to live.

While the series had played around with the idea of romantic feelings between Rose and the Doctor, it was only at the end of Doomsday that Rose, left on a parallel Earth, told him that she loved him. The Doctor began to reply, but only managed to get out her name before communication between the Rose's parallel Earth and the TARDIS was lost.

The Doctor's travels continue in 2007...