The Parein are an intelligent species native to the Delta Quadrant, assimilated by the Borg. Prior to their assimilation, the Parein were at war with the Farn. A number of Parein drones on a planet in the Nekrit Expanse, liberated from the Borg Collective, chose to resume their old conflict with the Farn. Their fighting continued until the neural link between them was re-established. (VOY: "Unity")
See also: Borg Cooperative