It is not made clear what regeneration this Doctor, or if indeed he is a direct regeneration (there is the Infinite doctor theory as alluded to in Zagreus). he is a kind, seemingly gentle individual who has issues over his weight. This makes his enemies underestimate him as he also comes across as a harmless wanderer, though this is far from the truth. In fact he is perhaps a more dangerous Doctor than his previous incarnations, in that he is prepared to break the Laws of Time itself if he has to to save lives. This is portrayed in "Lost and Found", when he travels across the time lines and interferes with an event in a vain effort to save a young woman. This act wipes the girl out of the time line and the Doctor is forced to live with the consequences.