Alex Dorring is an agent with MI-6.
Was is the more accurate word. He was an agent in good standing for several years, part of a highly specialized group of assassins making up the group known inside the department as Uriel. His code number was 192 and he was one of the best they had, one they called upon when the job was next to impossible.
Then a mission a decade ago went horribly wrong and Dorring became a prisoner in Iraq of some people you did not want to caught by. He would endure intense long term torture, which we are told about in the opening pages of the first recorded adventure, and all the time he was watching and waiting because he knew his chance would come if he just survived long enough. And he was determined to survive.
But after his escape, the story leaps ahead to modern time where he is a resident in another facility, this one nicknamed 'The Pit' and it was run by MI-6 being a repository for former operatives who are considered broken and not salvageable.
We will be given glimpses of what horrors had happened to Dorring that got him virtually comatose in that place. Told how before his incarceration he had been on assignment when he met and fell in love with the wife of a Russian oligarch he was surveilling. Told how for five years Dorring and his lover had lived a secluded life bring a young girl into the world. Then it all went bad. He was caught. They were killed. He was found by MI-6 in a remote part of Siberia, "half-dead, lying in a cell with two badly decomposed bodies that he refused to leave". "Ever since, he'd been here: the Pit, a place for broken agents. A place where broken things went when they had to be hidden away." That's when someone for some reason breaks him out and the next stage of Dorring's life begins.
Dorring is described as a big man many times throughout his adventures, for good reason. "He was tall, at least six and a half feet. Shaped like a bull. Huge, wide set shoulders". You would think that being his size would make people be extra cautious around him. You would be wrong and so would that. Dorring would see to that.