Guyen's cult: The people raised aboard the ark ship Gilgamesh as followers of Vrie Guyen, who treat him as a saviour and his upload as an ascension. They live outside suspension in a shanty town of cloth tents and work the ship for him.
Key Crew: Key Crew is the senior crew of the ark ship Gilgamesh, the small group whose suspension chambers stand in the ship's own crew room instead of among the cargo. They hold the command, engineering, science and security posts, and they are the people the ship wakes when a job needs judgement.
Non Ultra Natura: A human political faction on old Earth that opposed uplifts, engineered genomes and machines allowed past human limits. Its name means "no greater than nature", and one of its people destroys the Brin 2 station.
The Old Empire: The Old Empire was a human civilization whose star maps and technology guided the Gilgamesh to Kern's World. A civil war destroyed its colonies and devastated Earth, whose later human societies rebuilt among its remains.
The Tribe: The Tribe are the ship born engineers of the ark ship Gilgamesh and their descendants. They maintain the ageing vessel and call Isa Lain their Grandmother.