The villains of the crossover were the formerly imprisoned survivors of a race of alien parasites named Angon, Gemir, Glonth, Lissik, Pritor, Venev, and Slodd that could shapeshift into humanoid form. These humanoid forms were based on the initial entities they first encountered, a squadron of L.E.G.I.O.N. soldiers, most of whom perished. The bite of the Bloodlines Parasites was administered to the back of the neck by a mouth-within-a-mouth. This bite is intended to remove the spinal fluid for sustenance. This usually killed the victim for food, but occasionally awakened superhuman powers in the recipient. This was also the means by which the creatures could reproduce.