Vash returned to the Enterprise-D to attend a Federation Archaeology Council symposium held there in 2367. She was abducted, along with Picard and other Enterprise-D personnel, by Q, who cast them all into an elaborate re-creation of ancient Robin Hood legends. Despite this, Vash later agreed to join Q in exploring unknown parts of the galaxy. ("QPid")

She explored the Gamma Quadrant for 2 years with Q, but eventually left him to explore on her own. In 2369, Vash was discovered in the Gamma Quadrant by the runabout U.S.S. Ganges and brought back to Deep Space 9, bringing with her several artifacts from her travels. Vash attempted to raise money by auctioning some of her treasures at Quark's bar, but one of the artifacts contained a life-form from the Gamma Quadrant that generated a graviton field that nearly destroyed the station. Having been away from Earth for 12 years, Vash was tempted to accept an invitation from the Daystrom Institute to speak on her travels, but she ultimately declined. ("Q-Less")

from the Star Trek Encyclopedia