What if the Traveler is the true darkness which everyone speaks of? Think about it, the Traveler could have destroyed the Fallen's homeworld, which would be why they are called the "Fallen." If the Traveler attacked the Hive's homeworld, well I just think of it like if you poke a bee HIVE, then the bees are going to attack back. As for the Vex, the definition of the word "vex" is to cause distress to, and in the game they say the Vex are a malicious force... But what if the Traveler is the one who caused the Vex distress? All of these alien species fighting against the Traveler may overpower it, so it came to Earth and put everyone under its control in order to form its own army... That would make the Guardians evil as well, even if they're brainwashed by the Traveler's powers. This may be a wild theory, but I also don't believe it's just a coincidence that when you go out of bounds in Halo, it says "killed by the Guardians", I believe that is another one of Bungie's sneaky little tricks that we as the consumer are supposed to put together, in order to reveal the true plot of Destiny. Not to mention the Destiny poster in Halo 3: ODST and the other Halo easter egg(s) in Destiny, but hey, this theory is just my opinion and to me, it makes total sense. I'd really like to know what everyone thinks so please don't hesitate to respond, thanks and have a good day!