Ohohoho, thanks for the ask, anon! I love an excuse to build up the greater expanse of the Mirror World.

To begin, I'll cover Dark Mind's role here. He functions as the de facto ruler of the Mirror World, and is often referred to as its lord. This is because of his bond with the Dimension Mirror, which provides him leverage over the realm at large.

Dark Mind has remained unchallenged in this starring role, with the only likely instance of replacement being through his protege, Dark Meta Knight. This isn't expected to happen for quite a while, or at least until DMK proves mastery of the same, if not a greater set of skills. Regardless of whether reflections agree with Dark Mind's rule or not, for the foreseeable future, he's here to stay.

Importantly, not every reflection is part of an official faction, though it is typical for most. There are roamers and small groups out there who move around freely, but they're somewhat limited by where they can go. This is because factions fall into three main categories.