Scott McCoy is a member of the Delta Force.
Is and was, to be exact.
He was there when the elite special forces organization was created in 1977. He was there when embarrasing fiasco of Operation Eagle Claw trying to rescue the Iran Hostages in 1980 went so badly. In disgust, McCoy, then a captain in the organization, decided he had had enough and resigned his commission. It was his anger at the politicians and frustration at the upper brass that made him choose to no longer be a part of a military organization that he still loved and respected.
McCoy's return to active duty, as told in the first recorded adventure, comes five years later when his former commanding officer, Colonel Petersen, makes a personal appeal to him. With considerable reluctance but considerable respect for Peterson, McCoy agreed to once again wear the uniform and aid in a likely suicide mission.
McCoy's exact age during the time of his missions is not known but it likely that the man is in his very late 30s or early 40s. He is in excellent physical shape despite having left the regimen of the military a half decade before; he may have left the Army but the Army did not leave him. While he is lethal with firearms, both small arms and the long ones, he is especially deadly up close in hand-to-hand combat as he is an expert in martial arts.
McCoy stands 5'10" with brown hair. He is reasonably good looking though his face clearly represents the hard work and the struggles that he has endured during his service.
As far as I could determine, McCoy had been married to his career and so had no long term personal relationship outside the military.