Who are the Patrons?

Nexus has made references to a "Patron". Who is this patron? If multiple characters join at the same time, they are told there are "Patrons". So there is more than one, after all.
Who are these mysterious Patrons? Somehow, they have the ability to pay Nexus to kidnap them from their homeworlds, or wherever else they might be, with no warning, and no resistance.
Laughing voices and cheers in the darkness can be heard outside the range of Nexus's arena-carnival's spotlights, but nothing is ever seen. What are they paying Nexus with? Who are they already?!