Alright everyone, put on your tinfoil hats. [b][u]Regarding the idea of a simulation[/b][/u] Lets assume that we are in a vex simulation of the universe. Now, the Vex can "erase" us from time, apparently. The grimoire about the Vex talks about them as if they were some part of a computer program of sorts, or at least that they run like one. Maybe the Vex don't erase Guardians from time, but rather, their simulation... I think that the Traveler is not actually real, and that it may be something that either Dr.Shim created as a way for us to defeat the Vex, via their simulation, sort of an escape route. The Stranger is trapped in another simulation and found a way to cross over into yours, and try to alter the outcome. If someone can defeat the vex in their simulation, it may end altogether. The Stranger warns you on Venus that "A side must always be taken...even if it is the wrong one." THIS IS IMPORTANT. Think about this: we are trying to defeat every alien race that we come into contact with. One if a pirate-faring race, the other a military empire, and the last an undead army. It may be that in order to defeat the Vex, we have to choose (or end up forcibly) siding with one of the races. We are not on any side right now. [b][u]Regarding the theory of the story as a repeating time loop[/b][/u] Now, if we look at the other theory, which would say we are endlessly repeating history throughout billions of years, the story as presented in the OP makes a lot of sense. The Vex seemingly pre-date humanity by a few billion years. Yet, if you noticed in the Vault of Glass, the Precursor vex look brand new, while the Descendant models look worn and old. You would think Precursors would look old while Descendants would look new.... I think this suggests that perhaps the Vex do indeed operate outside the laws of our universe. In fact, I believe that for the Vex, time flows backwards. This would explain how they have seeded themselves into our past. We repeat history over billions of years, to the point where the Vex have gone further into the past each time and seeded our worlds. Any thoughts? Not sure how the Traveler would fit into this second theory other than maybe it came to stop them and break this cycle.