In "Metroid Fusion", Samus Aran is sent to the Biologic Space Laboratories space station because an explosion has happened there. The station contains X Parasites, viruses that can make a copy of the appearance and memories of living things that they are in. The Galactic Federation plans to capture the X Parasites to do further study of them. Because of how dangerous the X Parasites are, Samus has to destroy the space station to protect the federation from them.