Fiction:X-Gene

The X-Gene is a virus that infects creatures, much like Gar'Skuther's tentacles in Spore: Creatures. Except instead of just giving them tentacles and making them hostile, the X-Gene turns into an apex, demonic warrior. The X-Gene is thought to be created by the Grox scientists, but further analysis shows that it is a symbiotic species that originated from the Go-23-166-10-z galaxy, or as we know it, Andromeda.