In the mirror universe, Vash was an archeologist-for-hire who was partnered with Jean-Luc Picard during the 2360s decade. She was also his lover during the same period. They separated when she joined the Terran Rebellion.
In the year 2371, she enlisted Picard's aid in her and Noonien Soong's search for the Borg. After gaining Picard's assistance, she left to conduct a mission for the Rebellion on Celtris III, only to run into the Borg herself and be assimilated.