The Nexos, known as the Nexosporidium, are a sentient, humanoid cyborg species long thought extinct.
The Nexos first arrived in Las Paradiso, where they attempted to kill Crypto and Orthopox. He identified them as Nexosporidium Warriors, who were supposedly extinct. In an act of desperation, Pox orders Crypto to destroy all of Las Paradiso to erase any evidence of their being there and fled the city.
In Sunnywood, the duo assume Dr. C. Curt Calvin, leader of the Lunarian Church of Alientology, to be another DNA harvesting Furon on Earth. They stage an alien landing to draw Calvin out. Crypto confronts the cult leader in Sunnywood Stadium and demand he show his true Furon form. However a Nexosporidium walker appears and steps on Calvin, revealing he is actually human.
The Nexos found Crypto in Shen Long, where he had met The Master, however Saxon, his apprentice, became power hungry and formed a triad alinged with the Nexos to oppose him. Saxon kills the Master but is subdued by Crypto, who interrogates him at gunpoint amidst the sudden appearance of Nexos, and Saxon dies in the confusion. Pox deduces that the Nexos have been cloned on Earth, and only one organization could accomplish such.
Crypto discovered that the Nexos were bought back to life by Henri Crosteau and Francodyne Industries and set out to destroy the Nexo manufacturing operation in Belleville. Pox and Crypto learn Crousteau intends to create a virus to destroy the Furon DNA within the human genome. However, Crousteau still manages to create the virus and sends four Nexo walkers to distribute it into the river but is stopped by Crypto. Crousteau revealed only wanted to destroy humanity to stop the Earth from being polluted, and that he wasn't responsible for the attack on the casino and said that Nexos that attacked were rogues responding to a signal from the Furon homeworld. Crypto realizes that Emperor Meningitis is responsible. He and Pox set off for the Fourth Ring of Furon.
Crypto and Pox discover that The Master was alive, who revealed that he was the conspirator who set everything in motion and controlled the Nexos. Crypto becomes infuriated and motions towards Pox to slam The Master against a wall, killing him.