925th Universe
Jenny Over-There hailed from a seemingly-mundane universe known to Jenny Everywhere as the 925th Universe (PROSE: Family Business) where SatNavs all had knowledge about the geography of parallel worlds, hence their sometimes leading people onto roads that seemingly didn't exist. The M.F.S. office was located there, although it was unclear whether the Man in Grey was native to this world, (PROSE: The Tribulations of Jenny Over-There) having originated as the Man in Black. (PROSE: Open Sourcing, Lovie Dovie Stuff)
Though answering to a group of eldritch entities known as the Great Higher-Ups, the Man in Grey once confessed that he did not know which Gods, if any, were actually in control of this realm. (PROSE: Lovie Dovie Stuff) Besides Doctor Know, powerful beings with dominion over it included both the Great Higher-Ups and the Guardians of Time who created Tetra-None Hepta-Oct's people. (PROSE: Annals of the Jen: One Year of Jenny Over-There: Tetra-None Hepta-Oct and Doctor Know-It-All Talk it Out)
This universe was home to a version of the Land of Oz, which seemed to be a pocket reality of some kind, as it was not considered to be part of Earth. (PROSE: A Series of Queer Events, Lovie Dovie Stuff) The Greek Underworld existed as an afterlife; in one telling of her rescue of Grober, Marietta Over-There implied that Greek mythology happened to have the correct account of the afterlife in general, (PROSE: A Very Jenny Over-There Christmas) while a retelling of the same event suggested that there were many afterlives, with one's destination depending on one's beliefs or religious practices — such that Grober had only wound up in the Greek Underworld because he happened to be a fervent worshipper of the goddess Hecate. (PROSE: A Very Jenny Over-There Christmas (2024 reedit))
