The Heiress
Westfal is the only empire in the world to only formally recognize one deity: the Heiress. While in their early history they maintained the Imperial Truths - that all gods are but reflections of men, as unworthy of worship as man themselves - that fell apart with the Coming.
During the Coming, the empire was in a period of strife. No less than four rival claimants to the throne fought each other, and had been fighting in one form or another for nigh ten years. One of the claimants, Maxentius VI, was visited at the moment of his coronation in White Harbor by an angelic being. Calling herself the Heiress, she claimed to be the half-mortal and half-divine daughter of the First Hour.
At first, she was met with skepticism and horror. But she promised the emperor and those in attendance that his claim was true, and she would see that he won victory in the name of her dead father. And she did. A dozen of the emperor’s finest knights left the palace in White Harbor that day no longer mere mortal men, but Exalted.
They fought so fiercely that they could take on half a hundred men at once. The could call down fires from the heavens, and raise storm clouds of cinder and death. Outside of the battlefield, they could compel truths from any man no matter how stubborn, and they possessed magic beyond that of the finest imperial mages. Even long after the war was over, they found that the Exalted lived twice as long as any other man.
It is for this reason, this blatant show of power, that the Heiress became so worshipped in Westfal. Where other deities were subtle or closed off, the Heiress came to the empire directly in its time of need and bestowed her blessings. Even now, some are given powers like the Exalted. In Westfal, noble houses count how far removed they are from the original twelve Exalted, and it is considered a person of especially high pedigree who is a direct descendant. To the point that, like in the Empyrean empire of old, merchant families who wish to marry into the nobility will spend exorbitant sums of money just for the right to marry someone of such noble blood.
There is a dark reflection of this faith in Westfal, however. The Black Court are a secretive cult inside the Westfalian Empire, made up mainly of vampires and their thralls. Some are mind controlled into the cult, so goes the orthodoxy, into believing that the Heiress is not truly a divine being. That the Exalted were themselves thralls of Her will. That the Heiress uses the Crown of Maxentius to control the minds of the emperors.
Little is known about the Black Court really. One pervasive rumor exists, though. That they, in a dark reflection of the nobility counting their generations from the Exalted, organize themselves in a hierarchy based on who is most recently descended from their vampiric progenitor.