Seven of Nine began life as Annika Hansen, a human born on the Tendara colony in 2344 to civilian scientists Erin and Magnus Hansen. Decades before the Federation's official first contact with the Borg in Star Trek: The Next Generation season 2, episode 6, "Q Who", the Hansens suspected that the cybernetic species existed. Erin and Magnus brought Annika with them on the USS Raven's planned 3-year mission to confirm the existence of the Borg. When Annika was only four years old, the USS Raven followed a Borg cube through a transwarp conduit and emerged in Star Trek's Delta Quadrant.
Annika Hansen Was Assimilated By The Borg And Became Seven Of Nine (2350-2374)
Seven Of Nine's Tragic Early Life Was Told In Star Trek: Voyager Flashbacks
Even early on, Seven of Nine faced challenges to her assimilation. In 2368, Seven of Nine was one of four drones who were temporarily separated from the Collective. Because Seven had been assimilated while her body was still developing, Seven's human identity did not reassert itself at this time. Seven of Nine was singled out as the Collective's representative during Captain Kathryn Janeway's negotiations with the Borg in 2374, since Janeway refused the temporary assimilation that would make communication more efficient. The Borg plot to assimilate Voyager using Seven failed, so the Collective rejected Seven of Nine.