For fans of the cw flash series, this is supposed to happen between season 2 and the end of season 1. Fans who care about chronology would say Barry is supposed to be emotionally stressed at this time, so lets let this story be between Season 2 Episode 1 and Episode 2. For others who really don't care about chronological order, this is supposed to happen between season 1 and the start of 2All Rights Reserved