Epizanti

The Epizanti are an alien race that infects organisms with its DNA; slowly transforming them into Epizanti as well. Those that become Epizanti, retain their memories but are completely consumed by the Epizanti's instinct to deceive and transform other organisms. They do this using their races ability to switch between the forms of the host organism, and the Epizanti form. The Epizanti cannot infect anyone if they are not in their Epizanti when they attempt to transform someone into a new Epizanti.