James was a friend of the 12th Doctor. But he was different. He was a human but had the biology of a Time Lord, 2 hearts, Smartness, and everything. The only thing he couldn't do was travel in time and space. He could regenerate limbs, but very slowly from only the feet to the clavicle, but couldn't regenerate from the neck to the head. lots of people wondered how he came into the world. The doctor usually gave him books about everything about the universe saying "A time lord mind needs more knowledge than the Earth can offer" he was a expert marksman and usually helped the doctor fight villains.