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A nonbeliever himself, Sinclair's parents were staunch monotheists, hiring men to knock their son unconscious and transport him to Gemenon. On Gemenon, Sinclair met Lacy Rand and the two traveled aboard a jump ship to the Monotheist retreat where the STO trained its members. Enroute to the retreat, however, a group of polytheist rebels boarded the jump ship and held the recruits hostage, giving them the option of renouncing "The One True God" or facing execution. Sinclair and Rand planned to take action, but when the situation came to a head, it was Lacy Rand who acted, attacking the lead hijacker, Kevin Reikle, and forcing STO leader Diego to step in and reveal the situation to be a test (CAP: "Blowback").
At the Monotheist retreat, Sinclair and Rand were welcomed by Reikle and Diego in a reception and dinner for the new recruits. However, Sinclair and Rand were shocked to see the recruits that had "failed" the test put to death by firing squad - a sign to Sinclair of exactly what the STO was capable of (CAP: "Blowback").
An unwilling participant in the STO training, Sinclair was unafraid of the consequences of possessing such contraband as illicit drugs and a holoband in the dormitory - using the band to have simulated sex with Lacy Rand (CAP: "The Heavens Will Rise").
Witnessing Rand exert unexplained control over the STO's black market U-87 soldier robots, Sinclair attempted to question Lacy about her ability. As a way of avoiding further questioning, Rand began kissing Sinclair, successfully distracting him (CAP: "The Heavens Will Rise").
Later, Sinclair approached Kevin Riekle and Diego, telling the STO trainers that he did not want to be involved in whatever conflict arose from Lacy Rand's influence of the U-87s. Intrigued by Sinclair's position, Reikle and Diego enlisted Sinclair to kill Rand. When the time came to execute Lacy, Sinclair turned his gun on Reikle and Diego and attempted to shoot them, but the gun wasn't loaded. Reikle and Diego, unsurprised by Sinclair's turn, threatened him at gunpoint, but were caught off guard when several other recruits, appeared and fired rifles, killing the two men. Grabbing the key to the jump ship from Diego's body, the group of recruits prepared to leave Gemenon, however, Lacy Rand had another idea - activating the squad of U-87s and commanding them to follow her (CAP: "Here Be Dragons). Rand subsequently staged a coup over the leadership of the monotheist church and took on the position of "Mother," with Sinclair serving as her lieutenant. (CAP: "Apotheosis".)