The Valeyard was similar to several of the Doctor's incarnations, cunning and verbal, with a knack for manipulation. He had a bit of a temper, and was prone to outbursts, but generally calm and collected, traits of several incarnations of the Doctor. However, his actions were constantly defined by his egotism. The Valeyard would risk or sacrifice anything to ensure his own existence, even break the Laws of Time and kill his own past self and try to control the Dark Matrix despite the dangers its presence would pose to established history.
Canon has him supposedly between his 12th and 13th incarnation, I just sped things up a bit, because Nine did angry well, but Ten did Vengeance like nobodies business.
No second chances, he's that kind of man. And it should really be taken literally.
His current companion is Jack Harkness [Captainspain] because he's got a lot to avenge himself.