Before I say what I was thinking I just wanted to say that I'm actually happy that the story didn't answer all the questions we had, even though many people who don't like Destiny complain about it. It gives us more to talk about and makes things even more exciting as we learn more. So since we know (or are fairly certain) that the Traveler was once with the Fallen and we have seen evidence that suggests the Fallen were once a far more advanced civilization I was thinking about why the Traveler left them. Now this is just a thought, not really a fleshed out theory but it came to mind. What if the Traveler is responsible for all these races converging but not because it is the darkness but to fight the darkness. What if it has gone to each of the previous races in an effort to create a force powerful enough to defeat the darkness. Perhaps it started with the Vex, seeing as they are machines and so (presumably) is the Traveler. Similar the the Manhunters from Green Lantern, the Vex failed and could not defeat the darkness, instead becoming corrupted but not completely lost. And so the Traveler goes on to the Hive, Cabal, Fallen and now us. If this is true maybe we are supposed to be the people that can finally rally all the other races back to the light to fight the darkness together. That could explain why the Traveler sacrificed itself to save us rather than just abandoning us as it's appeared to have done with the other races. If this is true that leaves the question 'What is the darkness really?' and then also 'What if we can't beat it?' I think it would be really cool if after a few expansions we reach the point where we are supposed to fight the darkness but ultimately fail. Things seem like they couldn't get any worse and all hope is lost. I don't know what I'd like to see after that, maybe something unexpected like the Traveler doing something crazy or someone coming out of nowhere. I don't know. I hope you enjoyed my theory and find it interesting. Like I said I didn't look into it too much, just a thought I had when reading these theories. Any thoughts you have for or against it would be greatly appreciated,