James Xu is an agent with Black Force.
As explained in a similar write-ups for fellow agents and , Black Force is an unofficial American military operation, conceived and created by upper echelon officers, "top of the food chain" as King refers them, to take on the missions that they felt needed to be done but which few in their right mind would attempt and certainly none would admit to. As a completely off-book organization but financed through funneling from legitimate projects, it sent its men all over the world to handle "things that never would have ordinarily been sanctioned". The man in charge of this "group that didn't exist" is Lars Crawford and it was Crawford who personally vetted and selected the members of the group, pulling each man from the various Special Forces organizations in the U.S. military.
Each of these agents are considered solo acts, sent in alone to handle a mission and fully prepared to suffer the consequences if something goes pear-shaped. The isolationism is probably a good thing because for the most part, these operatives do not really play well with others, which, come to think of it, might have been one of the original reasons for the 'one mission - one man' directive.
"Black Force had never been advertised as an easy gig. In fact, it had never been advertised at all. Xu knew surprisingly little about the organisation, considering he'd put his life on the line for his country well over thirty times now. The job had no official protocol and no rigid instructions, which made it all the more satisfying when he pulled off the impossible."
James Xu is a Chinese-American born and "raised" in Brooklyn; that last word was in quotes because from the small references we get to it, it was a particularly harsh upbringing and one that Xu does not like to recall and never with any fondness. This poor childhood resulted in his learning at a early age how to defend himself and, more importantly for his future employment, how to bring pain and suffering to others. He is an expert in muay thai fighting.
Xu enjoys his life and enjoys his challenges. He is smart enough to know he cannot keep doing it for much longer but while he can, he will.