The Infested
From Star Trek: Theurgy Wiki
The nature of this threat to the galaxy was shrouded in mystery, but the parasites of the nameless darkness were not easily detected. They did not appear on tricorder scans, and while the crew of the Theurgy is still investigating their nature, the parasites existed in a state of flux. When the parasites were introduced to the hosts, the effects were both physiological and mental. Observations of closely studied hosts, Ensign Sonja Acreth and Dr. Lucan cin Nicander, made it evident that the hosts were granted superior strength and resistance towards neurological trauma - the stun settings of phasers included.
Based on what Ensign Acreth told her interrogators on the USS Theurgy, it was evident that the alien parasites were of chaotic origin, meaning to tear down the structure of all societies - actively trying to dissolve the Federation and all other galactic powers from within. It was not entirely clear why or how, but it seemed it lay in the parasites' nature to return matter to its original state - energy - and to do so on a galactic scale.
Moreover, they did not deem themselves individuals, but a nameless darkness without structure. Structure and direction seemed to be granted by their hosts in order to achieve their ends, making their existence a paradox. One thing was certain, and that was how the parasites thrived in the extremes of the process towards their intent. It was why they meant to spread the Niga virus, which would not only tear down all the Galaxy's societies, but also constitute a form of high-grade narcotic for the parasites and their hosts throughout the galactic outbreak.
