Genius Loci

You can think of them as guardian spirits. They're the reason the water that flows from the oases in the Red Sands is clear and pure, the reason sandstorms pass harmlessly over the cities. It's a bit more complicated than that, of course, but that's the non-technical explanation.

A Genius Loci, or simply "Locus", is an elemental spirit bound to protect one of the Three Cities. Each city has their own Locus.
The Loci were initially created by the Hells, as a way to efficiently control the cities under their rule. In the years since Theligose has thrown off their oppressive shackles, the Loci of each city has been slowly brought under the control of the Order of Binders. Each one now serves the interests of the population.