At the same time, Frank Horrigan was accidentally exposed to the virus. Unprotected wastelanders were exposed to low levels of FEV in the ruins, released after the base self destructed. The slaves and construction crews dug into the collapsed base, removing tons of rock. Eventually, excavations began in September. His unit was one of several assault squads tasked with capturing wastelanders to use as slave labor in the excavation of the Mariposa Military Base.

His various psychological problems eventually led to him being transferred to wasteland operations in 2236, after a psychotic blunder of undisclosed nature. This loyalty allowed him to be promoted in spite of his lacking intellect, all the way to the presidential Secret Service at a very young age (his 20s). His low intelligence made him extremely loyal to the Presidency, the Enclave, and its armed forces.