Yup in the Grimmoire and in the game it lays it out. The Traveler visited the Fallen (Elinski) first. They called it the Great Machine. That's why they came to the solar system. That's why the Houses attacked us. If it wasn't for the Queen stopping the House of Wolves. There would be no memory of the Battle of the Twilight gap. We would have lost. We would have all died and they would have the Traveller. Possibly enslaved. Who knows, if it wasn't for us they would have claimed both Hive and Vex tech. I hope we don't have to fight them like that by usage of time travel. Sources are the Grimmoire for Variks and Ruling House. Edit 1: Thank you everyone for posting! I'm learning quite a bit about the Fallen and I'm loving the theories being suggested.