I think the Exo are incredibly cool and fitting. I myself explain them as humans that were trained as special forces or some kind of military thing, or maybe even just a society of humans from some other part of earth. Definitely human though. Awoken on the other hand I think are totally random, still cool to me since I love fantasy and stuff, but... I dont know.. an elf or a vampire with a gun killing aliens in an attempt to save earth sounds crazy xD Still I guess one could argue that the Awoken have lived on Earth as long as we have, and unite with Humans against aliens because it is their home too. Maybe Bungie is suggesting that Ghosts and Vampires are real :P Anyhow I cant wait to play this and see what kind of cool Races and classes there are!! Will take me 3hrs to just choose the race, probably 4 to choose the class..