Brad Rafferty is an officer in the U.S. Navy.
Specifically he holds the rank of Commander and while we are told very early on that he was an intelligence analyst, we learn that he is stationed at the time at the Naval Station in Mayport, Florida where he was teaching a "class in basic nuclear concepts" being a "young, brilliant nuclear engineer". The two facts are not in conflict, however, as Rafferty has had his considerable expertise in nuclear weaponry put to use in becoming an expert in the actions of rogue states like Iran and North Korea.
Rafferty is into outdoor activities such as scuba diving and fishing and prefers to get to and from such enjoyments via his motorcycle. This love of action does fly in the face of an analyst's profession that is largely sedentary. He has no desire to be stuck behind a desk and looks for any opportunity to head into the field.
Rafferty is, from what I can tell, single with no one especially close to him in the romance department. He has a sister who is a veterinary and a father who is a retired Admiral. This last fact is important because of the danger of having to live up to a successful parent in the same 'business' but it is shown quickly that Rafferty is quite content in his own skin and has nothing to prove to anyone.
One aspect of his nature is summed up by a fellow officer who is not too flattering when he quips that Rafferty is "a boy scout. He would turn in his own mother if he thought she broke the law." What I saw of Rafferty, he is fairly straight-laced but nowhere near that level. Obviously, though, he can come across as such.