Anton was the sick man Alec and Mark found, sitting on a cot in a room in the landing pad. He told them that Deedee was given back to the survivors of her village and about the virus, known as the Flare. He explained that he and his coworkers were hired by the Post-Flares Coalition (PFC) and that they released the virus to wipe out half of the human population, due to the Sun Flares causing the depletion of resources for humanity. He said that even though the virus didn't work as it was supposed to on the test subjects, they continued with their plan to release the virus.
Anton told them that he had the virus, which was evident from how he spoke and acted, and that Mark and Alec surely had it too.
After Mark asked about Anton's coworkers, he told them that his coworkers were farther down the bunker, planning to revolt against the PFC in Asheville, which was the last safe haven in the East, in an attempt to take down the makeshift government and find a supposedly hopeless cure. After talking about this, he collapsed onto his cot and fell asleep. Eventually, Mark and Alec slept too.
When Mark and Alec woke up, they left Anton behind.