Look at that link I posted His movements are based on the alignment of the planets. xur is a manifestation of their power which I'm starting to think they too might be drawing from the deep but to somehow assist the light. the nine scare me and they're in a video game. Gravity and if you're a celestial body, chances are you're bound to have some kind of all controlling mind. I feel like there may be a division among the nine seeing as how one of the inner planets became corrupted by the vex machines, they took over the mind of mercury and turned it into a super computer. so the "Jovians" are now concerned and are helping the light to prevent any more of the nine from being corrupted and seeing as how the inner 4 are the only one so far to be effected (aside from earth) by vex it stands to reason that the Jovians are a leading effort in playing cards for the inner worlds.