Origin is the home planet of the Souls. It is the only place where the true language os the Soul is still spoken. Wanderer was born on the Origin. Most Souls born on Origin never leave, so Wanderer finds herself a bit of a celebrity for coming from there.
The Origin is most likely a gaseaous planet, and possibly a gas giant. It is made up of clouds and layers of colored gases. No surface is mentioned by Wanderer. It is the only place in which the Souls can survive outside of a host body for an extended time.
Their original hosts have a type of wings, multiple tentacles and silvery eyes. They are physically similar to Souls, and perhaps some type of symbiotic relationship developed between the two species.
Wanderer tells us very little about Origin. We do know that since Souls do not die, there is no grief. There is also no evil, but the absence of evil means that there is no chance to CHOOSE good.