Genesis

Genesis was a Forerunner world established to preserve life following the firing of the Halo Array, which was the host for one of the Gateways to the Precursor-Forerunner Domain, which Cortana used to achieve eternal life.

Its monitor was 031 Exuberent Witness, who was overruled by Cortana and the Warden Eternal, a Promethean commander, so Exuberent allied with Blue Team and Fireteam Osiris when they arrived on Genesis to chase Cortana, and helped them prevent her from trapping Johnny in one of Didact's blue-balled testicles.