Think about it! The Vex=Death: The Vex are an inescapable force, immortal through time and a danger to all forms of life. They bring end to the living as if they were a key component of the nature of the universe itself. The Fallen=Famine: The Fallen are a scavenging race, picking at the bones of the golden age. They are completely dependent on the machine gods that sustain them. All they do is consume. The Cabal=War: The Cabal are a race of warriors, their very fundamentals based on the dominance of other intelligent species. A WARpath has been left in their wake that nothing will stop. The Hive=Pestilence: The Hive exist as an aversion to natural order. They are a sickly force of mortality bent on a virus-like mechanism of sacrifice and mass production used to invade and hollow out worlds. See! In all honesty, I feel like the Vex and the Hive could switch roles, but I only say that the hive represent pestilence because of their diseased appearance. Also, the enemy races heralded the dark age, did they not? Thoughts? Edit: Regarding the conquest/pestilence debate, I used the pestilence interpretation because that's what I'm familiar with. In line with conquest: Vex=Conquest Cabal=War Fallen=Famine Hive=Death