Societal Structure
Every part of the empire has a stratified society. This is not regarded by the overwhelming majority of people as being in any way unusual. The exact nature of that stratification varies from part to part of the empire, though, as does the expected role of nobility.
The Imperial Territories
The Imperial Territories have formalised various tiers of nobles, from the empress herself to the ducal and comital houses, most of which hold substantial power, to the baronial houses, which do not, at least not without massing together, and even the holders of individual estates. The Cult of Valon is stronger in the Imperial Territories than anywhere else in the empire. The cult's teachings are that strong nobility are vital to an orderly society, so some nobles regard it as a religious imperative to ensure the strength of their houses, and indeed that of nobility more broadly.
The idea of fulfiling one's duty is sacrosanct to Adanans. Once a pledge has been made, it must be followed through on. This does not mean mindless obedience from vassals: if their liege is a poor ruler, and especially if their liege violates agreements, then it may be proper to oppose them. This is not done lightly, nor would the typical Adanan act cynically and contrive reasons for which they have opposed their liege; most would only do so because they truly believe that to be proper.
Adanans might place minor nobles into positions of authority within a larger house, because they are still after all nobles, but the elevation of commoners to such positions is regarded as improper.
Adanan nobility regard the appropriate scope of noble responsibilities as being to ensure sound rulership, including to provide security, to administer their land, to set and enforce law, and to fund public works. They do not trouble themselves with commerce though, which is left entirely in the hands of burghers. Merchants and guilds hold substantial clout in Adanan towns. The nobility do not view this as being at odds with maintaining a strong nobility, because such matters are not the responsibility of nobles.
There is no serfdom in the Imperial Territories, nor are commoners who are not directly employed by a noble house expected to owe any particular duty. They rent their land or pay their dues and carry on with their lives. The idea of raising a peasant militia would be mortifying to any self-respecting Adanan noble, who would regard it as a sign of them having failed utterly at their own primary duty, which is to provide security.
The Realm of Dyria
The Realm of Dyria is similar to the Imperial Territories in many respects, with its distinct tiers of noble houses. The idea of noble duty manifests differently. Nobles are not generally deemed to have an obligation to the institution of nobility itself. The first responsibility of a noble is for their individual city, town or village and they are expected to see to that as best they can, although of course they do not always succeed. A noble's duty to their liege comes second to their duty to their own home. A prudent liege will ensure they are on good terms with their vassals, even moreso than they already might elsewhere in the empire.
When placing people in positions of authority, Dyrians will firstly seek other nobles from within their house, then vassal houses if there are sound relationships, and then commoners, but generally only if the commoner is to be granted a post within their own place of origin.
Dyrian nobility, as with Adanan, regard the appropriate scope of noble responsibilities as being to ensure security, to administer their land, to set and enforce law, and to fund public works. Commerce remains primarily a matter for burghers, but it is not improper for a Dyrian noble to be involved with it, providing their involvement relates to the wellbeing of their home city or town. A Dyrian noble being involved in mercantile matters not related to their home would be outlandish.
As with the Imperial Territories, there is no serfdom in Dyria. Dyrian commoners are expected to serve their village, town or city just as the nobility are, with the degree to which they must do so being dependent on their wealth. There is no interdict on a commoner moving to a new town - indeed, mobility is relatively high compared with other places in the empire - but a newcomer to a place is inevitably regarded with a measure of distrust for a time.
The Realm of Hadash
The Realm of Hadash has far, far fewer nobles than anywhere else in the empire, even though Hadash is the most populous part of the empire. Noble houses Hadash all exist on a single level, with only the monarch above them - currently King Misic - and above Misic, there is the empress in Sanctuary. There is simply no concept in Hadash of subdividing land to parcel out to noble vassals. A Hadashi noble house owns all its land outright.
To be born a Hadashi noble is to be regarded as blessed by River and Sun: nobility give and promote life and they watch for evil, but with all the potential for capriciousness that River might have, and the same lack of omnipresence as Sun.
The idea of Hadashi nobility conducting all their own administration is not even considered. There are far, far too few of them to adequately administer a fraction of their land. Commoners often hold important and influential positions in Hadashi courts, from administrators to judges to generals.
The responsibilities of Hadashi nobility are much the same as those of Adanans and Dyrians and ultimately relate to sound rule. The primary distinction is that there are so few Hadashi nobles that it is entirely possible that commoners may fill many major posts in a house. However, if a noble of a house issues an edict, a commoner must adhere to it, regardless of the noble's official post or lack thereof. Competing nobles issuing contrary edicts can be chaotic. A head of house is ultimately an absolute ruler and may not look kindly on their family interfering too much with the house's functioning.
Hadash's population is vast and even more than the rest of the empire are farmers. None are serfs; all rent from a noble house. The systems to administer all of this are sprawling webs of bureaucracy operated by house servants.
The Commonwealth of Hana and Lonin
About one in ten people in the Commonwealth is a noble, which is about ten times the rate of the Imperial Territories or Dyria. It is a fact that occasionally grates on other imperial nobility, because a noble from the Commonwealth might be someone who happens to hold a patch of land with three farms on it. There are not strictly different tiers of nobility in the Commonwealth. The noble who holds three farms has the same vote at the sejm, or parliament, as the one who holds an entire city. Inheritance within a noble house is not strictly hereditary, nor is it chosen by the deceased, but is voted upon within the house. The entire business of voting is quite alien to much of the empire. Being a noble comes with a great deal of associated duty.
Commonwealth nobility, with the exception of the Grand Duchy of Lonin itself, not use hereditary titles. The head of a house is named a boyar. The monarch is elected. The head of House Albalaski holds the title of grand duchess or grand duke, but even within Lonin, no other titles are in use.
Commonwealth nobility engage in their own local animistic worship and sometimes that of other gods. The Cult of Valon holds a great deal of fundamental appeal in the Commonwealth and association with the cult is widespread.
The idea of a commoner being appointed to a position of authority in the Commonwealth is tantamount to absurd to nobility there. Nobility have different duties to commoners, and there are plenty of nobles available for all manner of positions.
The responsibilities of Commonwealth nobility extend far beyond those of anywhere else in the empire. Hana can be a dangerous place, and Lonin is dangerous to the point that visitors occasionally question why anyone even remains there - to which the answer is given that it is because it is their home and their duty. The martial tradition in the Commonwealth is extremely strong. There is no formal law mandating that a noble must send assistance to a distant house, yet many do, or even march to their aid themselves. There is great prestige in that in the Commonwealth. This culture is what allowed Lonin to survive for so long.
The Commonwealth practises a mode of serfdom. The majority of commoners are bound to the land and may not move from it without the dispensation of the noble landowner, which is not often given. One sure route out of serfdom is to prove the potential to be an able warrior and to enter the service of a noble house as a soldier. Commoners resident in towns rather than in the countryside are less restricted, though the Commonwealth is not particularly urbanised.
The Grand Republic of Thasen
The Grand Republic of Thasen is a plutocracy. There is no culture of duty or obligation, but of cynical politicking. There are a number of aristocratic houses, but ultimately real power is vested in the hands of three big houses. Thasen contains a few large cities, which are the home of the aristocratic powerbases, though the houses don't necessarily own the cities outright. Thasena houses each own a patchwork of land here, there and everywhere across the Grand Republic, rarely continguous and quite possibly even intermingled with that of outright rivals. The Grand Republic votes for its leaders in its senate and as praesens, but the three big houses ultimately decide most of the outcome, because the votes of the wealthy hold far more weight.
There are no hereditary titles in the Grand Republic.
Commoners can be and are appointed to jobs within houses, which operate as much as businesses as they do noble houses. The functioning of the state is, on paper, determined by the senate in Benetta. Bureaucrats based in various institutions in Benetta supposedly deal with administration, though whether the state itself ever receives funding is up to the three houses, and if it does, it is usually for something to their benefit.
There is simply no culture of noble responsibility in the Grand Republic.
Commoners are routinely caught in de facto serfdom with no route out, through contracts drafted and enforced by the noble houses.