1. The Hive stripped their Light and/or destroyed their Ghosts 2. Lost in the Whirlwind. The few survivors were brought under other banners 3. Possibly something of an exchange program to bolster both Houses. That explains also why Draksis wears Devil colors 4. Possibly the emblem of the lost House of Scars 5. He bolsters and repairs himself with robotic parts 6. Probably because 1) the Fallen weren't very advanced and accepting in the wake of the Whirlwind and 2) neither were we. We saw each other as threats 7. Possibly the Light of the Traveler keeps them out, or perhaps it's because the Traveler is still their creator 8. Nine very mysterious bastards