Michael Memphis is an agent with the CIA.
He is an unofficial one and he most definitely is not an operative by choice. He had tried very hard to leave the world of special operations far behind him, with very good reason, but unfortunately an act of altruism and bravery will work against him when he comes to the attention of the CIA. A sector in that organization needs someone of Memphis's abilities and they are determined to not accept a 'no'.
The time period of his activities is the second half of the 1980s. The date is very important to the storyline because Memphis is South African by birth and upbringing and that country was still very strongly under the reins of apartheid. Anyone not white was considered less than a full citizen - and in the case of the several "homelands" created to segregate blacks from white, not citizens at all. Memphis was not a believer in that policy; his father was a British citizen who had moved there and married Memphis' mother and neither "had any overtly political affiliations. His father had been a professor at Cape Town University, Memphis's mother had worked for the South African national phone operator. Both parents were dead. Memphis was an only child. The guy was a loner". The military had given him a second family.
He had served with honor and distinction in that government's Special Forces, rising to the rank of Captain and leading his own team of operatives. He would have likely stayed there for the rest of his working life had an incident not caused him to abruptly abandon that position. As we are told very early in the first recorded adventure, an operations took his group and another team into Angola after some very nasty people who had fled there from South Africa. The groups fell into an ambush and the CO of the other group felt a village was to blame and ordered a total destruction of the people. Memphis objected and when his arguments did not stop the planned bloodshed, he eliminated that CO. Capture, planned court martial with life in prison expected or death, an escape and a long journey out of the country and then out of the continent followed.
He came to the attention of the Agency when he was in Los Angeles stopping three pedophile lowlifes who had kidnapped a teenage girl. They did not care for his interference and he found it best to deal permanently with them. Then he tried to disappear but by them he had been noticed. A man named Bates decided he was "instinctive, calculating - he's real smart" and just the sort of non-American operative he could use.