So during the Eleventh Hour arc, Istus reassures Merle that it’s ok if he works for her because she and Pan are friends, and then during their date in the next Lunar Interlude, Kravitz says that he’s sure he can pull some strings to keep Tres Horny Boys in business because the Raven Queen is friends with Istus
So like
This could indicate that Istus is just, like, super popular on the Celestial Plane and gets along with everyone, but I think I prefer to interpret it as Istus, Pan, and the Raven Queen are all members of the same heavenly clique