Dos is the second universe, in which roughly 2/3 of the rest of the majority of the story takes place in. It is the universe with the Illuminati.
During Eden-Alpha, Dos was created. Then, a virus evolved, which was known as CC13. It could have wiped out the life on the planet, and a human caught it. The CDC got involved, and kept it top-secret. They hired someone to be shrunken down and put into a ship to combat the virus inside the Patient 0's body, and they did so. However, one virus managed to escape, and Dark Mind manipulated reality so the virus got put into a portal to Uno, and at the same time, a Dride got sucked into a portal to Dos, and they both collided together, and the virus became Virisis, the Virile Virus.
At the same time Dos was created, Itanimulli was created, and the events described on the page Illuminati happened.
Also, several creatures were blended together by the Dark Mind to become the mutants: Gelidus, Obsoletion, Potterror, Arthificioda, Crimsonfly, Undeniable, and Envied. They all came together to help Dark Mind begin the end of all 3 universes.