Sometime after the CBI outbreak began, Perez was stationed at the Seattle quarantine zone under Sergeant Ward's command. He was present in the 2020s when the dissident group called the Washington Liberation Front (WLF) was created.  He subsequently served in the war against the WLF alongside Green, Adams, and an unnamed soldier. Eventually, the WLF defeated the military, successfully killing Torres and Ward.
Perez and his squad fled to the radio outpost at the city's theater and planned to hide out there. However, after three days, the unnamed soldier had come down with a fever. Fearing for his life and having only their uniforms, the soldier convinced Perez and the others to head to the nearby hospital and take supplies from within. Perez and the others left that night. The unnamed soldier appreciated their efforts. However, days passed and Perez and his squad did not return to the unnamed soldier.