Ive always wondered whether the traveler visited the other races, raised them to intergalactic level then left, at which point the races society collapsed, and so they chase the traveler, each time a new race is added, till the caught up on earth, and tried to force the traveler back. It would explain why they have neither destroyed the traveler completely, nor returned to their origin space. Also would make sense why these 'minions of darkness' fight each other. The nine might be the remnants of one of these races who choose less direct methods to get what they want.