The parasite is the elementary relation: one-way, irreversible, both noise and guest, both interruption and new order. Cascades of parasitism constitute systems; every host is already a parasite of another. Noise is not pathology but the condition of complexity; the interruption that collapses one chain consolidates a more intricate one. Exchange is secondary; abuse is prior. Stations and paths form a system only because interceptors divert flows of food, message and energy. There is no system without parasites. The host/guest ambiguity, the thermal exciter, the static that becomes information—these are the atomic forms of relation. Parasitism is the black box of the collective.