Sean O'Reilly is an agent with the CIA.
We are told in a blurb about the first recorded adventure that O'Reilly is considered a "disgraced" operative and the first actual mention of the man in that story refers to him as a "former agent" with a personal comment about his being "a real piece of work". Obviously there are a collection of people who do not have a very good opinion of the man so it falls to us to decide whether they are right or just not understanding the fellow.
On the positive side of the O'Reilly ledger, according to these same folks, he is "someone we were happy to use for some of the most difficult and sensitive missions", or at least he was back when they used him, which was over a decade ago, starting back in 2009. Now he is considered an enemy of the state.
Our first meeting of the man has him in the capital of Bangkok working as a start-up in the black-market weapons business, all part of his overall plan to find out who killed a colleague and "plummeted Sean's own life into chaos".
The first three adventures we have of O'Reilly all deal with the fallout of a very nasty operation spearheaded by powerful and unpleasant people in Washington, D.C. who were seeking to become even more powerful by being even more unpleasant. It is not healthy to get in the way of such people or even look like you might be or appear to be a dangerous loose end which it seems O'Reilly was and so they marked him a disgraced and an enemy and put out an elimination order and went on with their scheme. O'Reilly didn't follow the gameplan and let himself get dead. He took exception to it, as a matter of fact, and decided to fight back.
- When an operative is reminded, "we can't waste taxpayer dollars on pointless witch-hunts", he counters, "Even if they find witches?"