As has been noted elsewhere, the Imperium is ruled over by an autocrat known as the Imperator, whose power is virtually limitless. They are considered the living representative of the Name, and as such they exist in complementarity (in theory) with the Council of Prefects that rules over the Church.
Though the Imperator’s power is, in theory, without bounds, there are a number of factors that frequently influence how much they are able to wield. Foremost of these is the Senate, which is comprised of the various heads of the Houses, both Great and Lesser, that are the leaders of the many noble families, as well as some of the more wealthy and powerful merchants that inhabit the Imperium. There are, however, two “chambers” of the Senate. One, the senior chamber, is comprised of the nobles, including the Counts, Dukes, and Kings of the various administrative units, as well as the aforementioned Heads of House that are not rulers of these large units in their own right. This chamber wields all of the power and serves as the primary advisory body to the Imperator. The other, lower, chamber is comprised of the merchants and guild-masters. The Imperator is in charge of convening the Senate and having her or his decrees acclaimed by both groups. Except in extenuating circumstances in the history of the Imperium, the Senate has largely done as the Imperator wished. They also have the responsibility of acclaiming the Imperator upon his or her accession.
The position of Imperator has, by long practice, been assumed to be hereditary, even though this is not a strict rule. Instead, every Imperator that has established a steady rule has nominated their successor to reign with them as co-ruler, preferably when they are in middle age (as this supposedly cuts down on the possibility that an impatient heir may attempt to do away with a doddering senior partner). This has, for the most part, worked to the advantage of the Imperium as a whole, as it ensures a smooth transition from one ruler to the next. On occasion, however, it has resulted in conflict between parents and children, as the latter grow impatient for their turn to occupy the throne. This was the case with the Bastard’s War, in which a bastard son of Imperator Tiberian V slowly ingratiated himself with his father, thus spurring the ruler’s legitimate son to ignite a rebellion.
Through the years, the Senate has come to occupy a more pronounced and active role in the governance of the realm. Most of the various nobles who reign in their own right have historically treated their territories as their own private kingdoms, with little to no regard for the wishes of the increasingly-marginalized Imperators. Up until roughly 50 years before the time of the novel, this has been the case, and most people think of themselves as following their local lord before they think of themselves as subjects of the Imperator.
However, several recent Imperators have moved back to the model earlier established by their predecessors, taking on an increased role in direct governance. Part of this has stemmed from the increasingly restive and invasive Korrayyin and their allies the Haransharin, both of which have required strong forces. The current Imperator’s father became known as the Hammer for his ability to strike swiftly and without mercy, bringing fear to his enemies, both inside and outside of the Imperium. Indeed, he was well-known for his ability to bring the rebellious and fractious lords of the realm to heel and, unlike several of his predecessors, he took to attending meetings of the Senate, allegedly to make sure that he was aware of the goings-on in his realm but, far more likely, to strike fear into those who might be fomenting rebellion.
They have also returned to a model of court ceremony that had not been seen in several centuries. Now, it is required that all of those who wish to gain an audience with the Imperator, no matter their estate or class, must perform several rounds of obeisance, in order to show the proper humility to the one who is considered the earthly representative of the Name. This has served to ensure that the nobility understands their place in the divine ordering of the universe.
As a result of this semi-divine status, all Imperators are required to be crowned and anointed by the eldest member of the Council of Prefects. This is to ensure that the Imperator is blessed with the power of the Name as well as the acclamation of the Senate. This typically takes place in the Magisteria, the great church that sits at the direct center of the capital of Aïonis. The ceremony, as with all things connected to the Imperium, is intended to remind all of those gathered that the Imperator reigns with the utmost secular and temporal authority, and it is also a day in which the common people are treated to the greatest festival that any of them are likely to know. Recent Imperators have known that it is the common people who wield the true power–though they don’t realize it–and have acted accordingly.
Though coups are relatively rare, they have occurred for various reasons. The Imperator’s person is considered inviolate in theory, but as with so many things this does not always translate into consistency in practice (as the incident of the Bastard’s War makes abundantly clear). There are always those for whom the way that things have always been done are no impediment to their own ambition. It also doesn’t help when Imperators die before ensuring that their successor is secure on the throne, which happened with Talinissia’s father Philophanes, who died while she was still in her 20s, setting the stage for the armed uprising of her brother and the bitter Siblings’ War that nearly toppled the Imperium into utter chaos.
As the events of the novel begin, it remains unclear how much the position of Imperator has been damaged, and whether Talinissia is the one to bring stability. History, after all, has a nasty habit of repeating itself.