If you look at the Ghost Fragments I forgot which one it is, it's either under the Fallen, or Earth. But I specifically remeber reading one and it was a conversation between a Ghost and a couple Dregs. The Ghost was blackmailing the dregs, saying if they didn't listen then he'd have 10 Titans crashing in their roof. And if you think about it, we basically listen to our ghost like a dispatch. I personally believe we're some type of post apocalypse military police force. Which brings up a couple more theories that I think majorly tie in. Most of civilization was wiped out by something when boarding the ships, we find that out pretty early in the game. Ok well in the Dark Below DLC. The Warmind is told to be capable of such things. And that's why your ghost tells you to go defend it from the Hive. Hint, Hint. I think the speaker/traveller is responsible for powering up the Warmind and nuking humanity, so he could have the ghost revive them and turn them into his own army. I've always thought we were evil ever since I noticed the names of characters in this game. We are "Hunters" Titans" and "Warlocks" Which falls under the evil side of names wouldn't you say? We kill "Knights" "Wizards" & even "Priests" so from the abundance of context clues.. We are pretty damn evil if I do say so myself...