Saul Booker, AKA Sachiel, is an ex-CIA operative, sometime hitman, fierce martial artist, and irrevocably damaged individual.
The True Order of St. Nathanael (aka Verus Ordo Sanctus Nathaniel, the True Order, Verus Ordo, Verusians, etc.) was a serious case of small-town religiosity gone bad. An apostate Catholic splinter started when a charismatic priest, Eli Trumbull, showed up in a small town in southern Michigan, his dogma an esoteric combination of mystic Catholicism and new-age psychic crystal-waving. It wasn't long before the local bishopric tried to crack down on the schismatic, but he left taking a chunk of the congregation (and the town) with him. The usual cultish pattern of finding just the right patch of middle of nowhere to set up the compound started, but was combined with a surprisingly savvy infiltration of both Catholic dioceses and New Age enclaves by those of the True Order (who called themselves either by their Latin name or as "Verusians," depending on which group they were with).
It was later that the worst of it started, but with its increasing influence (disproportionately directed towards the successful and intelligent) and militancy the True Order became the subject of both casual, and eventually public, scrutiny. This prompted the training of the Heavenly Choirs, groups of young men and women from within the Order who were tasked with the harassment, intimidation, and eventually even the occasional execution of the church's enemies. Firm in his belief and massively indoctrinated, a 16-year-old Saul believed he was literally doing the work of angels and was spiritually "controlled" by them on the missions his priest-handlers assigned to him. He always returned a hero, and eventually became highly regarded within the Order for his facility with fisticuffs and infiltration.
But these sorts of stories never end well, and following a CIA infiltration the True Order found itself the object of what the news outlets would refer to as "New Waco." So far as any unsealed records indicate, all members of the compound and the group were either found dead as part of a ritual suicide designed to purify them for entry into Heaven or gunned down after opening fire on encroaching government forces. The reality is slightly more complex, and while it is true that a slaughter took place, it is a little-known fact that a great many of the "Angels" were not among the dead.
Having found a cadre of highly trained, fanatically loyal, and morally certain men and women with no qualms about "righteous war," the CIA quickly made sure to absorb them into their ranks. Years of de- and re-programming yielded killers with meticulously washed minds and very little that marked them as players in any traditional agency power structure. The Angels became human missiles. This was Saul's life from his early twenties until his mid thirties; an undifferentiated series of jaunts to foreign locations to root out what his handlers insisted were the unjust and the sinful. For many of the Angels, these were suicide runs, but Saul managed to keep coming back alive and eventually ended up one of the agency's most reliable intrusion and assassination tools.
Records are unclear about when Saul, who still used his Order codename "Sachiel" went native, and Saul himself certainly isn't talking. The only information that ever comes up in connection with these events is a mention of The Valis Affair. What is clear is that he has severed all ties, and at least seven spines, that tied him to the CIA. In a stroke of luck that it is not clear he has been able to comprehend, the CIA classified him as an "unrecoverable resource" rather than as a dangerous criminal, reasoning that he had no record of killing, or indeed any violence at all, when not directly programmed or imminently threatened. Still, lacking any usable skills or personal acumen beyond training imparted specifically to allow him to pass for a member of ordinary society Saul rapidly turned to freelance assassination as a means of self-support. He now lives nomadically, and life is still an undifferentiated series of jaunts to foreign locals that all seem to end in crushed necks and collapsed skulls, but he is calling the shots as he tries to recover from his two decades spent as an instrument of fear.
Saul rarely works under any alias other than his own. Most of his jobs hinge on his remaining unseen, anyway, and on the occasions when he interacts with others it is practically all he can do to project the facade of an ordinary human being. Much about him is subtly wrong, as though even the most basic social gestures are accomplished by rote.