Xur is someone or a collection of someone,'s that CHOSE there date to live being the reef in the jovian planets (planets beyond the reef and just out of reach of the light as the light only travels as far as the reef. By stating they CHOOSE to go all the way out there too the "outer world s" as he calls them. The nine choose to live out beyond the reef where as the awoken did not. And that last part is taken directly from a grimore card.