Seclusion is a gas giant in the Milky Way that was once part of the Forerunner ecumene. At some point the Forerunners established a gas mine on the planet. The planet was originally thought to be uninhabitable due to its harsh conditions, however, an avian species was discovered beneath the gas mine. The station was shut down and it, and its personnel, were left as a decoy for The Flood. Eventually the Flood discovered the station and almost overran it but a Warrior-Servant, known as Adequate-Observer, scuttled the station, destroying the Flood and saving the avian species.