Primus, Lord of Mechanus

It is said that at the center of all the planar system lies the plane of Mechanus. But who lies at the center of the thrumming clockwork that makes up the plane?
It is unclear if he is a god, a modron with great power, or an Inevitable, but what is known that all on the plane of Mechanus answer to the one known as Primus. Truly neutral, with no care for either the plight of other nor accruing more power for himself, Primus seeks only to maintain the order of the planes. He is a curator as much as a ruler, and running afoul of his grand design is to flirt with an the ire of an uncaring being. So too does he serve as judge and juror for many such things, for who would better serve to act without bias?
To this end, the deals made with his blessing are often upheld by entities known as Maruts, hulking golem-like humanoids made of steel and iron, with a single large organic eye taking up much of the upper portion of their body. In their chest is embedded a golden disk, upon which is inscribed the details of the deal the Marut has been charged to maintain. Break the deal and the Marut will bring you to task, no exceptions.