Michael Cailen is a security expert.
At least that is what he becomes after his life somewhat slows down and he is able to have a job. Prior to that he was a man on the run.
Cailen joined the U.S. Army at a young age and soon was a part of the elite Green Berets and took part in a few missions with them. Then his talents were needed elsewhere and the military transferred him to the Navy Seals, giving him even more interesting training and skills. After several more nasty assignments with them, he was again "transfered", this time to black ops duty occasionally seconded to the CIA, the very group that would later be hunting him.
Cailen and his friend, Shaun, had been visiting some of Shaun's relatives in a small town in China. Since Cailen, who had a gift for languages, spoke Mandarin and wanted to do something different, he decided to go along. Early one morning halfway through their planned time there, they were awakened by screams created by the villagers who were being slaughtered by men with swords and knives. The killers were not expecting trained soldiers to be there and were unprepared for the carnage that Shaun and Cailen unleashed. Leaving one man alive to answer questions, they learned only that the killers had been paid to wipe out the community and were hired by someone they thought was CIA. While Shaun remained behind to protect his family, Cailen returned to America and was immediately attacked by a man who, under pressure, admitted he was CIA.
For the four years leading to the first recorded adventure, Cailen was A.W.O.L., living under the radar and trying to learn as much as he could about who was after him and why, a task made complicated by the fact that he was certain if the most powerful intelligence gathering organization tracked him down, he would be dead. One thing going for him was an ability to finance his operations through the un-voluntary donations by drug dealers who Cailen forcefully convinced to contribute.
He is described in the opening pages as "tall and muscular with gently tanned skin, short dark brown hair with just a hint of curl and smoldering brown eyes. He was incredibly handsome."
This description comes from Jessica, the second major player in the drama with the CIA. She is a computer hacker and a very good one, able to make a good living in the computer security business. Then a friendship with a Russian hacker turned very deadly when he got in trouble and turned to her and she became a target as well. She would have been a dead hacker if not for the fact that the same people after her were the ones after Cailen and their plan to take out both at the same time did not account for how good Cailen was.