Steve Vail is an agent with the FBI.
Was an agent. Now he has a vocation which is a whole lot less 'glamorous' and considerably safer; he is a bricklayer, or as he corrects himself on that, a brick mason. That is no euphemism for any other line of work, such as a Mechanic is really a paid assassin. He lays bricks. Good, honest work that he can be pleased with at the end of the day and people pay him to do it and no one is trying to kill him while he does it. More importantly, no higher-up is likely to yell at him for insubordination and get fired up over the way that he goes about his work.
That last was definitely not the case when he was a special agent with the Bureau. As a colleague remembers his time with that law enforcement department, Vail had been "probably the best word-the kindest word-is recalcitrant." Or as it was a bit more colorfully put, "they used to say he bit off his nose to spite his face so many times that he actually learned to like the taste." Those were reasons why the Bureau had issues with this agent.
The reasons why they put up with him, for as long as they did, was "Vail had this reputation for finding people. He handled all the federal fugitive warrants for Detroit homicide. They said whether someone was gone fifteen minutes or fifteen years, he'd find them". That extra special skill made him well respected by everyone and frequently on call for that ability. And that is largely why the Bureau reluctantly found it necessary to come asking for his help, however distasteful it was to some of them.
Oh, one other interesting point that plays a factor in the two recorded adventures. The person tasked with re-recruiting him for the first case is Deputy Assistant Director Kate Bannon, someone that Vail did not know at the beginning. When told it would be she to approach him, she had to wonder, Vail [despises men in authority. What do you think his reaction will be to a woman?" Pretty good, as it turns out.