Man.... You just REALLY need to read the Grimoire on the Hive. Just do that and you'll realize just how far off you really are with this. The Hive are the only race in the game that seem to willingly follow the Darkness. The Vex seem to be outside of everything except for their "God" in the Black Garden. The Fallen seem to have been forced into serving the Darkness, and the Cabal seem to be running from it after realizing that they couldn't defeat it. I honestly thing that by the end of the Destiny series we(Humans, Exo, and Non-Reef Awoken) will have some allies with the Fallen and the Cabal much like how we made treaties and became allies with some of the previous Covenant Forces in Halo. Not with the Vex or the Hive though.
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This was actually meant to be more of a speculative fanfic than a theory, and according to every website I visited, wherever you got that info is fanfic too. Also, my OTHER theory involves all the enemy species doing what you say the Cabal are doing, but I haven't posted that one.