Tony sullivin is a 25 year old human , he meets the doctor when he stays in hid friends (bob reeves) mansion and is attacked by Sontaron Krall,he then stumbles upon the TARDIS and the rest is history.He looks like the Doctor because of a time space glitch. He and the doctor are like brothers until he is shot and killed by the master.This changes the Doctor making him into a angry , moody and dark man again.He is greatly distressed when the doctor starts to regenerate(Diomonds are forever) .