Who the heck are "The Nine" that Xur work for? Are they an underworld group that competes on the political stage of The City, vying for control, focused more on the petty doings of the average populace but still helping Guardians by offering exotic items...for the right price. Or are they one of those fatalistic groups of ronin from a fallen house trying to regain its former glory, searching for warriors to join the cause and donate some coin. Pretty much acting like another Future War Cult, etc. faction?
I was also thinking that maybe this is a veiled reference to a larger arc of the main story line. Bear with me here :)
So is "The Nine" a reference to the number of planets in our solar system (YES I AM COUNTING PLUTO :P)? I believe so and have, while sitting bored at work, decided to follow that to the whatever crazy tangent it goes. I am thinking that this group "The Nine" is a group of guardians privy to a secret entrusted only to a few, that The Traveler is not dead but dormant. Awaiting the gathering of "The Nine" who were present during the end battle, when The Traveler was supposedly sacrificed to halt The Darkness. These nine were the greatest of us, the most attuned to the different aspect of the light that the traveler had spread among our system. The Nine, fearing the encroaching Darkness, held a council with officials from the city and every faction still fighting to determine a course of action and ask The Traveler for guidance. During this council a suggestion was made, The Darkness will always follow the light of The Traveler and so The Traveler must leave so that we could live. Stemming from the discussion following this suggestion it is decided that they will ask The Traveler to leave our system and take The Darkness with it. In reply "The Event" occurred wherein The Traveler utilized the majority of its power to vanquish the main armies of The Darkness and push its "Core" back for a time. Following this, The Nine hear the voice of The Traveler whisper in their minds something along the lines of "to leave is to concede your spark to the darkness, only a gathering of light will vanquish the dark, when the time comes you will gather and our brilliance will overwhelm the dark. stretch out and reclaim, prepare and build, for the blight shall return" (or something cryptic of that nature lol). Afterwards, these Nine help rebuild and go out to explore our system....and are lost. Time passes and the 'prophecy' is retold and a group forms "The Nine" to gather the spirits of these original nine and restore glory to the light with the newly gifted Ghosts. Unfortunately, the Hive senses in some way this turn of events and seeks out these spirits as well, hoping to find a way to destroy them for good.
Sorry that ended up a little longer than I thought, but basically if this were the case I see a lot of story tangent that could be fun, like that 'mysterious female exo' on the moon actually being part of a dark cult that wishes to snuff out the light and works against "The Nine", and so on and so on. So please post any thoughts, any links that can give me more info on the nine, or just your own theories on it :) Thanks for reading and I apologize for the lack of organization, sitting at work just typing this in a one shot :)