Guinan was a mysterious time-sensitive being who worked as a bartender on the USS Enterprise-D. In 2386, she began receiving memories of things she felt she should not actually remember. When the Eleventh Doctor arrived on the Enterprise and experienced the same problem, Picard brought him to Ten Forward to meet Guinan. They had a familiarity with each other that they shouldn't otherwise have. These memories were due to their abilities to sense disturbances in time, and they realised that the Cybermen had somehow altered history in order to bring their respective universes together and forge an alliance with the Borg. (IDW: Assimilation²)