User blog comment:Mike Gilbert/What to expect/@comment-7622429-20140613185504

Well, the Ghost did say in one of the trailers that it has been searching for the player character for centuries. And it has been centuries since the Collapse. I theorize that perhaps the Traveler, when it sacrificed itself to save Humanity from the Darkness centuries ago, left its legacy in the form of the Ghosts, breathing life into these drones by its dying breath (not literally). They then search for those strong enough to continue the Traveler's battle with the Darkness, to prepare for its inevitable return and guide them.