Carlos Olivera was chosen by the Umbrella Corporation to join the U.B.C.S. He joined Delta Platoon, Company A, along with Nicholai Ginovaef and Mickhail Victor. Their original mission was to wipe the virus threat (The Zombies) out of Raccoon city, as well as save as many survivors as possible. Instead they found themselves cut off from all communication to the outside world stuck in the middle of a zombie infested city.
Carlos meets up with Jill Valentine throughout the game as the two of them attempt to escape Raccoon City. At one point of the game, Jill becomes infected by the T-Virus after a battle with the Nemesis. Carlos would become playable for a short period of time in order to retrieve a vaccine for Jill. Despite having to fight off hordes of flesh eating zombies, zombie dogs, zombie crows and even the Nemesis, they both made it out alive and well.
Carlos makes an appearance as a major character in Resident Evil: Apocalypse, the second installment of the live action movies based on the games, and reappears in third install, titled Resident Evil: Extinction.