“Jovian” could mean from anywhere. Jupiter, Saturn, Uranus and Neptune are all Jovian planets. Io is technically Jovian, since it’s a moon of Jupiter. Nessus as well. Also Titan. So the “Jovians” could come from a number of planets or moons. But, the common theory, or at least my theory, is that the Jovians, or at least Xûr, are/is a creation of the Nine in order for them to interact with us. Orin is one of these creations as well, since she calls Xûr her “brother”. Think of it. The Nine were described to be dark matter beings with tendril like appendages sometimes. What does Xûr have on his face...?

I thought Xur was some sort of prototype being made by the nine to interface with us. At least that what Orin says during Reckoning.

<I had a theory, but that was lost. Alas, we do not know their nature. Are they dark matter or are they just Dark? What side is the Nine on, and which Nine hold that stance?>