Matthew Riker is an agent with QS-4.
QS-4 appears to be a private enterprise with deep connections to the Pentagon and to the general military-industrial complex that routinely works hand-in-fist with the DoD. The company recruited from only the best schools, which usually means an Ivy League education. They also required military service, a nice little show of patriotism for the board members, though those destined for leadership roles need not have actually seen 'serious combat'. The down-and-dirty work that QS-4 was asked to do on many occasions, the kind of work that made it so valuable, was left to people with skillsets like Riker.
Considering the kind of work that QS-4 does, work that no one would want ever acknowledged but which powerful people in the government would deem needed doing, secrecy is a key component to their operations.
Which means a strange and tenuous anonymity was vital. It was important that the key players knew of QS-4 and how well it handled sensitive matters clandestinely. It was also vital that groups like the press and the general public remain blissfully ignorant of it or its accomplishments. Killing for the State is good business if only the State knows it is being done.
That brings us back to Riker and the statement that he is an agent. It is more accurate to say that he was and that he will be an agent.
Riker hails from a low-income family with a father who sometimes had a job and sometimes did not. Often lunch at school was his only meal. He might have gone down a very bad path except for a high school coach and a penchant for wrestling. Oddly, when offered a chance to head to college on scholarship, he chose to enter the military.
He found a new home and a new discipline with the Navy SEALS and for several years was content. Then came the offer by one of his last commanders to join QS-4 and for several years he worked as one of their very best operatives. The number of confirmed kills he did for that organization was impressive.
And taxing. He decided enough for enough and he wanted out. Unfortunately QS-4 did not have an agreeable severance policy. A tense situation arose. If QS-4 decided to terminate Riker's employment, literally, it could go badly for them since Riker was very, very good as survival. It would also not go well for Riker in the end. A very strange agreement was reached. Riker could leave QS-4 as long as he never, ever used his 'talents' again.
So when we meet Riker, he has gone 6 years as a civilian, living a very quiet life on a small farm raising bees. His main source of income is the honey that he gets from his good number of hives. He is alone and for the most part content.
And then he met the young woman with the little girl who were running from some very mean men and Riker's pacific life went away and so did his agreement with QS-4.