Paul Decker is an officer in the U.S. Army.
And an agent of the CIA.
And a rebel.
And maybe who knows. It gets very, very confusing.
When we first meet him he is a Captain in the Army who has the job of carrying the nuclear football wherever the Vice President goes [note, this is the first I've heard of the VP having such a person so I am assuming poetic license is in play]. He is also a drunk. From the way it is described, he spends most of his off-time feeling sorry for himself and drowning his sorrows in tequila. In our introduction, we find him pouring out his last bottle determined that it would stop now but he did take a final shot beforehand so the prognosis is not good.
Why he is a Captain is not known because we learn of the many, many years of exemplary service he has given his country to the detriment of his marriage and his family so you would expect his rank to be considerably higher than O-3, especially since we learn he is very near the end of his career.
"Paul was a tall man, roughly hewn, but considered handsome on some plane. Like an unfinished piece of sculpture, he was sharp edges not yet rounded off. It was not simply massiveness he conveyed; it was also a sense that he would not allow age to overcome him. He was designed by a good architect rather than a skilled painter." We also learn that "he didn't know if he had any good qualities, or fight, left in him."
Furthermore, it is said in the second adventure we have that "he was, first and foremost, an adept soldier, a poor excuse as a husband and father second, and lastly, a very proficient drunk. He achieved most of his success as an alcoholic. Yet he had the best training ever provided by the army. A ranger, yes, but much more. He was a new breed of soldier. He may have started out as a grunt in the field, but had developed an understanding of computers the Internet, and the capability of conducting cyber warfare. He was the first 21st century warrior: a 6'2" piece of granite, still working out every day with a vengeance in spite of the booze at night."
So from all that we learn that while he seems a pretty lousy excuse for a man, he is, as I stated, an officer in the U.S. Army.
But we also have adventures where he is an agent with the CIA. He was retiring from the Agency in one adventure and had just started his retirement in another.
Still again when the country goes to hell in a hand basket, he becomes a rebel fighting to help bring back civil rights and so much more.
One thing to know about the adventures of Paul Decker is as bad as things are in one adventure, they will be so much worse in the next.