Excellent post! The concept of Light and Dark has certain merit when it come to Good and Evil. I would argue however that there is no actual single Entity that is the Embodiment of what are two separate principles. The idea that the Traveler is a rounded structure in and of itself, represents the concepts of compassion and nurturing, teaching and forward thinking as an idea that is as old as Infinity. Conversely. the pyramid ships represent, as you said, are straight and pointed, hard edged and sharp. The Sword, as it were. There is a Balance that must be struck between the two at all times. The idea of God in my view is that He is that Perfect Balance point. The One that exists between the Light AND the Dark. We as His creation are this same sort of embodiment, yet we are still immature, still trying to figure out for ourselves where that point is. If the Drifter is what he appears to be, than I think his own role in the story is like that. Yes he "collects" motes, little pieces of the Dark but that is where he believes his Balance is. Making deals as an Arbitier for Angels and Demons as the most recent trailers might suggest. But who knows what goes on in Bungie's collective heads ehh...