There are two kinds of nobility: the duyin 'nobles', descended from the original clan heads who founded the kingdom and have their own land, and the ludin 'barons', who are appointed by the Crown and administer a town and its surroundings in the king's or queen's name. They look down on one another, duyin calling ludin upstarts and ludin calling duyin decadent, but the general consensus seems to be that the duyin are slightly more noble.
Traditionally the king or queen, or more accurately the royal family (the house Velain), has the power and the other noble families have the money. The royal house has lived on loans and mortgages for centuries, but recent treaties with Iss-Peran promise more income for the king.
The largest duyin houses are, in order of importance:
Velain, the royal house, dirt poor, all the land they have is the city of Valdis which is mostly mortgaged to the house Brun and a few bits of private hunting ground. Any land held by the ludin nominally belongs to the Crown as well, but the income from there tends to flow back to where it came from.
Brun, very rich, incorruptible, with a strict code of honour. If you're a Brun and get yourself corrupted - anything from pocketing part of the taxes to joining the Guild of the Nameless - you're thrown out of the family, "go mend your ways and then we'll see if you're worthy to bear our name again". They got as large and important as they are now by being invariably good to their people, knowing that contented peasants work a lot harder. They own about a quarter of all the cultivated land in Valdyas and strive to make it more than half in the next hundred years by bringing as yet uninhabited areas into culture. The treasury of the house Brun also handles Court finances - much of it is Brun money anyway.
The houses Velain and Brun have intermarried so much that they would be one family by now, were it not for the fact that the royal house puts a lot of effort into perpetuating its name. Not that the house Velain is so eager to rule: every Velain knows exactly how far he or she is from the throne, and most are pleased to be far enough from it.
Hayan, with patchy land, mostly around Ildis and in western and southern Lenyas, and a lot of money though most of it is tied up in their estates. There's a particular kind of wealthy shabbiness associated with the house Hayan: tumbledown houses, threadbare carpets, but always the best food and wine available.
The house Eraday fell into disfavour after its head, Fian astin Eraday, made a pact with the Nameless, fortified the town of Erday (with the house with the Otters, the family's ancestral seat) against the king and the Guild of Anshen (and indeed anybody), and took the non-semte population hostage, threatening to kill them if the king didn't submit to him. Moryn astin Rhydin, Eraday on his father's side, cut Lord Fian's head off; King Athal destroyed the town and declared the house Eraday dissolved. Some Eraday nobles have kept their name in defiance, some call themselves Nusan after Moryn's residence in Tal-Nus, some have forsaken the house-name completely, and others still consider themselves noble but await the foundation of another house.
Rhydin, either the largest of the small houses or the smallest of the great houses, based in Idanyas on the south coast where traffic to and from Iss-Peran has coloured the House Rhydin in more than one way. This House has rather more than its statistical share of psychically gifted people, but on the other hand they tend to keep out of things more than average. Semti of the house Rhydin are either in the Guild of Anshen or unaligned.
There are also a number of smaller duyin houses, such as the house Rizean in the far north, that gave its name to Rizenay, and the house Tavalyn ("Little Velain") that descends from an offshoot of the house Velain. Most of the small houses own only one or two manor-houses and a small plot of land, if they have not disappeared entirely by intermarriage with more important nobles. Calling the house Rhydin a 'small house' is a matter of tradition rather than reality.
The ludin are usually not chosen from the duyin; a ludan title is not formally hereditary but the ruling monarch tends to choose the heir of the body unless he/she is really incapable. New ludin can be appointed if the old one oversteps the bounds of propriety. For instance, when the ludan of Tilis asked King Vegelin the Great's help against a peasant revolt the king sent a Guild runner to investigate, who found out that the peasants were revolting because the baron was levying twice the normal amount of tax. The king went to solve the problem himself - he wanted to visit the southern part of his country anyway - banishing the baron and appointing the peasant leader, Arin, instead. This was one of the present king's ancestors.
Baronies are Veray in Ryshas, Lenay, Rizenay, and Tilis. Sarabal also counts as a barony, though there is only the castle and the village and the barons haven't paid taxes to the Crown for generations.
Ildis should really be a barony as well, but it's traditionally independent under the Crown. It's administrated by the town council consisting of representatives of the most important craft guilds, the Mighty Servant to represent the temple of Mizran, a noble (for the last two hundred years or so this has always been a Hayan) and the mayor, elected by the council from among its members.
Essle is considered ungovernable and left ungoverned except by its self-appointed council.
By common law the eldest child inherits everything, but is expected to provide for younger siblings. In commoners' families this is usually not an issue, unless the family is very rich; in that case the parents often make a will overriding it.
Offspring who stand to inherit are (1) a woman's children, (2) a man's wedded wife's children if they haven't been acknowledged by another man before the marriage, (3) any children a man acknowledges and the mother doesn't dispute, (4) children officially adopted by filing a deed with the Temple of Mizran. To acknowledge a child, all a man has to do is either say that it's his in the presence of two witnesses other than the child's mother, or put it down in writing at the Temple of Mizran. There are no bastards as such; having only a mother is perfectly respectable.
Nobility (the house-name) is always inherited from the noble parent, even if the other parent is a commoner. Many people who have a right to a house-name don't use it, however, unless they have to do something official. When two nobles of different houses marry, they can choose which name their children bear. It's not unusual for adults to use their father's house-name when they had their mother's as children, or vice versa, or to use different names in different situations.
Duyin have a house-name, the name of their family preceded by astin 'house'. For the rest, the usual matronymic naming convention applies; if Ayran's mother is called Rava and he is of the house Brun his full name is Ravei Ayran astin Brun. People from his own social circle talking about him, in a formal or neutral context, will call him Ayran Brun and informally, or if it's important to know which Ayran (it's a very common name in the family) Ravei Ayran. Subordinates talk about him as Ayran duyen 'Lord Ayran' and address him as Ayran duyne (vocative of the same). People who can address him informally simply call him by his given name. In some circles, especially among young nobles in a 'clubby' atmosphere, only the house-name might be used ("what do you think of that, Brun?").
Someone who is of the ludin but not actually a reigning baron or baroness, goes by (barony name) (mother's name) (given name): Tileis Mailei Alyse 'Alyse, Maile's daughter, of Tilis'. Reigning barons have the barony name in the locative and after the mother's name: Mailei Tilies Alyse 'Alyse at Tilis, Maile's daughter'. Equals talking about Alyse would call her Tileis Alyse if she was not reigning, and Tilies Alyse if she was. To subordinates, she is Alyse duyen or, in the vocative, Alyse duyne 'Lady Alyse'. Note that there are no separate male and female forms for duyen, and that ludin are addressed as duyne even though they are not duyin.
It's clear where you are, but boundaries are fluid. It does make a difference what kind of family you were born into, and among the great noble houses there's a bit of rivalry, not always friendly, that tends to put Brun and Velain at the top, Hayan just below, Rhydin lower still but they don't care, and Eraday - what's left of it, now - firmly at the bottom and they do care.
In general it's easier than in a totally rigid class structure to get into touch with people of a different class from your own, but you have to pick your context carefully. The Guild of Anshen transcends class boundaries almost completely; so do, to a lesser extent, the Guild of the Nameless and student life at the Academy in Ildis.
Commoners who marry nobles become part of the noble family, though they don't acquire the house-name. King Vegelin the Great's father was a commoner, but Vegelin was no less a Velain than his daughter, whose mother was Lédu Lástalfái, the youngest daughter of the King and Queen of Velihas.
Nobles can administer high and low justice to people under their responsibility, but usually ordinary crimes are referred to the bailiff's court (civil justice) and offences involving misuse of semsin to the Order of the Sworn. The bailiff may or may not belong to a noble family; this goes by local tradition. In Ildis the bailiff is usually a burgher, in Turenay the office has been held by the local head of the house Brun for centuries.
If a noble turns to crime, he or she is subject to the same justice as everyone else. There is no real class justice in that nobles are punished less severely, or sentences are carried out differently, but crimes committed by nobles tend to be covered up more. A noble murderer is properly executed, but the cause of death is construed as 'a hunting accident' or something similar to protect the family name. This can make a full turn if it's necessary to set an example, and some families prefer setting an example to covering up.