Ersatz, a filly born of a changeling and an undead pony, is thrown into the world of Fallout: Equestria. Lost and alone, her unique regenerative ability helps her survive, but without the help of a few friends even she would surly perish long before her rescue. Las Pegasus, the Hoover Dam, and the finite resources are being faught over each day between two warring factions, the Legion and the Republic. Will she join one of them, or form her own faction?