C.J. is Sandeman's son and Ames White's younger brother. He was locked up in a mental hospital controlled by the Conclave after his father turned away the cult's beliefs. Sandeman left after finding out that C.J. wouldn't survive their test.
Months after Manticore burns down during a meteor shower, C.J. escapes the facility, stealing a ceremonial snake when it is passed onto him. He finds refuge in Terminal City, where many Manticore alumni have gathered. He appears to them, claiming to be an X5, and sees the runes that have appeared on Max's wrist. After realizing that expressing his interest in the runes had been a bad move, C.J. slips away and returns to his hideout, but Max finds him later on and he reveals to her that Sandeman is his father and he created Manticore to find a way to save him. Max coaxes him to contact Sandeman and meet with them, but C.J. calls Ames instead and hands her over as a show of brotherhood. Ames is able to read the messages on Max's body and claims that she is the one their father had been talking about. Hearing this, C.J. knocks Ames out, apologizing and saying that Max is his only hope of surviving, and helps Max escape. Ames shoots him before C.J. can get inside the van containing several captured transgenics, and C.J. tells Max to leave him behind.
He is last seen back in the mental hospital, bound and gagged to prevent him from escaping once more.