Here is a theory for you... What if the Traveller is nothing more than an AI in a terraforming ship, sent ahead of a colony ship. But somewhere along the way the colony ship doesn't arrive. Terraforming ship decides to find someone else to help colonise worlds... Traveller finds us... but what if ANOTHER Traveller was out there... a Black Traveller who terraforms the planets the Fallen originally were on... before they became the fallen. The terraforming engine infects the Pre-Fallen and create the Hive... which is why the Hive and the Fallen are fighting... The Hive drove the Fallen from their home planet and then follows them. The Fallen will then hate the Terraforming ships... including our Traveller. The Hive just plain hate everything, being space Zombies after all.