Following the destruction in the wake of the Great War, many of Clarksburg's residents left for Morgantown. Those that remained became sick from the chemicals in the Toxic Valley's water. Eventually, the town's population was driven down to just three: Cooper, Jill and Ande. Jill and Ande were soon killed by a yao guai, leaving Cooper alone. She decided to leave Clarksburg and search for survivors elsewhere.
Cooper Lu is mentioned only in Fallout 76.