(Operation Raccoon City's backstory)
The Nemesis Beta is fairly weak without a host. According to the information available from the website revealed by Inserted Evil, the Nemesis Beta has the ability to control other B.O.W.s by gaining access to the central nervous system. B.O.W.s controlled by a Nemesis Beta Parasite is much more powerful and dangerous than un-controlled counterparts. The parasites themselves can also spray a kind of pheromone that zombies can easily detect. Targets covered in such pheromone are more likely to be attacked by zombies.
In gameplay trailers, the parasite is shown to gain control of zombies by decapitating them and latching onto the host's neck, in effect replacing the zombie's head with the Nemesis Beta.
In the Echo Six mission, Root of All Evil, a parasite attempted to latch onto a T-103. As it did so, the parasite seemed to partially melt into the Tyrant. Initial effects observed of this combination were a dramatic growth of the parasite's legs while the Tyrant's head remained intact. The gestalt creature, now called the Parasite Super Tyrant, was encountered again in the mission Longest Yard. By this time, the parasite and the T-103 have more or less merged into one, with some of the parasite's characteristics flowing over those of the Tyrant. What was once the parasite's head now partially covered the T-103's exposed heart while the enlarged parasite legs were five times bigger than before, enabling the Parasite Tyrant to walk on them, dig underground or use them as weapons. In addition, the monster's left arm has become massively overgrown and clawed while its right arm looked skinny and stunted by comparison. The Parasite Tyrant also retained the parasite's ability to spray pheromones and can summon normal Nemesis Beta Parasites by pounding its insectile legs on the ground.
Despite the merge, the minds of the parasite and the T-103 remained independent of each other to some extent. For example, whenever the T-103 was unconscious, the parasite was able to continue fighting. Also, the exposed glowing membranes of the mutated parasite became new weak points for the Parasite Tyrant. The monster was finally killed when Dee-Ay shot its heart at close range with an automatic rifle and then jammed a grenade into a crevice next to its heart.
- The NE-Beta's ability to control other organisms makes it similar to its cousin the NE-α Type; however, it does not appear prone to killing its host like the Alpha model.
- However, unlike the Alpha, which exists under the skin of a host, the Nemesis Beta latches onto the back of a host and smashes the host's head off; rendering it exposed and vulnerable to attacks from behind the host.
- Developer Interviews for Operation Raccoon City had hinted that new B.O.W.s could be introduced to the series. The NE-Beta is one from the B.O.W.s, aside from Elite Hunters and the Parasite Super Tyrant.
- When bonded with a zombie, the duo becomes more dangerous than either one of them would be separate; the Beta increasing the speed, intelligence, strength, and durability of the zombie. It also stated that it IS able to spray bile which causes nearby B.O.W.s to become more aggressive and target those covered with it.
- According to the Leaked Audio, William Birkin took part in this project and it was kept as a secret for most researchers within the company.
- Once its hosts are damaged, it will crawl off of its body and look for another undead host.