Let me start off by saying that speculation at this point has little value, but is entertaining nonetheless. Pretty much everything here is pure speculation. TLDR at the bottom. What I'd like to discuss is the nature of all these bad guys crashing our solar system. So far, we have the Fallen, Hive, Vex, and Cabal, which (if I remember correctly) are lumped together in the "Darkness" category. I don't know if "the Darkness" refers to a separate entity, but it seems like a blanket statement to describe everything that wants us dead. Regardless, its pretty clear that these guys followed the Traveler here, which deigned to provide a great many things to the solar system. We have some kind of magic, Exos have sentience, and there seemed to be some kind of leap in technology, all of which helped launch the "Golden Age" before the Traveler began to wane. This is all good stuff that generally puts the Traveler in a good light. Good on you, Traveler. However, the question stands as to why all of these creatures would chase this thing across the galaxy; these creatures who are advanced in ways we've yet to fully grasp. My guess is simple, and may or may not have crossed your mind already. The Traveler no doubt came in contact with these disparate cultures at one time or another and did the same for them that it did for us. This would help to explain the similar technologies and powers our enemies possess. The Traveler may be the legacy of some long dead civilization that served as a friendly, autonomous ambassador to create friendly ties with distant civilizations by providing great gifts (or, more maliciously, readied them for integration). Whether or not this is true, it is likely that it bounced around a fair few times, trying to contact a variety of species. This is probably when things went sour. The civilizations it left behind followed in its wake, chasing after their miraculous provider. Each civilization it touched most likely came to rely on it for its gifts, and likely had golden ages of their own before crumbling. I would guess that the "Darkness" is fighting over possession of the Traveler, and the ball just so happens to be in our court, not so figuratively speaking. If the Traveler didn't essentially crap out on our doorstep, it may have left to continue its journey like before. We may very well have chased after it, too. Be that is it may, right now we've been initiated in a galactic game of kill the carrier. Anyone who likes speculating, please discuss! Also, I'm no expert on Destiny lore, so kindly correct any false assumptions you see if you like. [b]TLDR: The Traveler bounces around, providing for disparate civilizations. The Fallen, Vex, Hive, Cabal (and maybe others) may have been included in this. Now, they chase after the Traveler to keep it for themselves to sustain themselves.[/b]
What if there traveler was a kind of technology created by a great civilization to protect and sustain them. With this tech providing the "light" they needed, they became the superpower of the galaxy, expanding and colonizing new worlds. A new empire. The fallen, hive, vex, and cabal each meet them with force, and were nearly destroyed. After hundreds or even thousands of years of prosperity the keepers of this tech became complacent, and began to turn against one another. A civil war began within the empire, two sides, each obsessed with annihilating the other. During this war the fallen, hive, vex, and cabal formed an alliance. They defeated the war torn empire with haste. Nearly everything the empire created was destroyed, but not the traveler. The alliance soon crumbled when the true power of the traveler was discovered. As they fought for control over the traveler it was able to deal a massive blow to all factions. The damage wrought allowed it to put lightyears between itself and its pursuers. This was crucial as the traveler was able to bring on the Golden age in Sol, hoping to prepare humanity for the struggle that was sure to follow.