Vex's homeworld in the Hoven system (Red Dwarf star)

Its a freezing, Mercury sized planet with an extremely thin atmosphere at the edge of the system. It sports a very small ring and two asteroid moons: Dreg (larger) and Gulch (smaller).

It is highly populated, being home to extensive mining operations below the surface. The whole planet is owned by a single dragon known as the Matriarch. She is CEO of super-corporation Aqua-Mareen Industries, and leader of the Beryl Creed, her own religion that believes she is a celestial deity who will guide her followers to a higher state of being.

Vex grew up in one of the main cities on The Rim, where she was born into the Beryl Creed. Her parents are high priests and therefore, she was to become one as well. She ended up escaping the planet by being a stowaway on a cargo hauler, and left the system. The Matriarch states that any born into high priesthood cannot leave the Creed, meaning she sees Vex leaving as blasphemy.
While the Matriarch is busy with many things constantly, she is searching for Vex in the background. Whether that be through periodic scrying or sending out zealots to track her. Vex however, has a charm she keeps on herself at all times that blocks any attempt at scrying so the Matriarch cannot locate her through magical means