Dominic Grey is a private investigator.
More specifically, he and his employer, Viktor Radek, are investigators of cults. As such he would likely have never made it into this collection but his history and how he got into his current line of work, not to mention some of the people he takes on as clients or as enemies make him decidedly eligible.
When we meet him in the first recorded adventure, he is and has been for some time employed by the Diplomatic Security branch of the State Department, tasked with the thankless job of keeping American diplomats all around the globe safe as they head into situations both friendly and quite hostile. On the mission we first follow he comes up against a very, very old religious sect and nearly dies from the experience.
He comes away from it with a new calling and a new career, looking into sects and cults and fanaticism all over the world, becoming the person to go to when dealing with such groups.
He did enjoy his time with the DSS although he would have to admit to himself he actually looked forward to trouble in a way. "Most of his days were spent investigating routine visa and passport fraud, and escorting high-ranking government figures to their favorite restaurants. The travel kept it interesting, but outside of a coup or assassination attempt, diplomatic security was not an action-packed profession." As he would be amused about later, be careful what you wish for.
His tenure with the DSS was not always smooth sailing, though. He is told by his friend and sometimes mentor that he had "to play the game". This go-it-his-way attitude is nothing new. He had it while in the Marines Force Recon, nearly getting a court-martial for refusing to fire on a crowd of villagers.. He had it while being recruited, and ultimately passed over, by the CIA when their ethical profiling exams revealed his "moral compass guided him" in places they might not like. It was while considering and rejecting the Foreign Service that he looked in the DSS and liked the chance to travel.
It will be after meeting and working with Professor Viktor Radek, a professor of religious phenomenology, that he really found his calling.