Okay, so I'm having trouble finding anything on the Nine. But let's make the assumption that they're the one pulling the strings. Releasing Skolas and the like. They work for their one means and help the Darkness or the Guardians equally. Come to think of it, Xur gives us Exotics, and the Darkness is given Skolas. Maybe they helped release Eris because they knew that would bring about Oryx. I think we're on to something.