Noble Houses of Eridane

The Arnosti Eridā́neva (ar-NOHS-tee air-eh-DAHN-ay-va), or Noble Houses of Eridane, make up the main fabric of social and political life in the Kingdom of Eridane.
While in principle all of the Noble Houses (Arnosti) are of equal standing, there is a de facto ranking among the houses, although it is considered extremely crude to speak of such things. Instead, there are various "traditions" used in referring to relationships between Houses.
The Arnosti Eridā́neva are never explicitly ranked, nor is there even any official distinction amongst them in terms of power or influence; but there is a generally understood division between the power and influence of some Houses compared to others. To quote an aphorism from the elven diplomat and socio-political theorist Arrantiel Partelithar (BF 1405-854), “Someone has to lead, and others have to follow”. And so some houses are understood to be “leaders”, and others “followers”.
Of course to be more diplomatic, the term used to refer to a close relationship between Houses is “association”, though that is always used to refer to a patron-client relationship - two (near-)equal houses with a close relationship are said to be in “alliance” rather than be “associated”.
In fact there are three tiers of Houses in Eridane, with the first (none dare call them higher) tier forming associations with the second tier, and the second forming associations with the third tier. There are a number of third tier and a small number of second tier houses with no associations to the second or first tiers (respectively), though almost all second tier houses have associates in the third tier.
It is a major faux pas - indeed, not just rude, but seen as crude, even vulgar - to refer to any house as being “better” or “greater” or “above” (or their opposites) to another house. Instead the discussion always refers to associations and alliances. Houses in the third tier may have a sort of association with a first tier house through their association with a second tier house, but any such connection is always “through their association with (middle house)”. The same sort of talking around the rankings happens in terms of alliances, but in many cases tier 2 and 3 houses are not held to the alliances of the houses they are associated with.
The direction of the relationship is indicated in the language used. From the upper level, a lower level house are “associates”; from the lower level, the house is "associated with" the upper level house. Thus Elenereth says that Triscaryn are their associates, and Triscaryn says they are associated with Elenereth. Triscaryn will say that Voronna, Lucaryn and Iarlen are their associates, and those houses would say they are associated with Triscaryn, and may sometimes say they are associated with Elenereth "through their association with Triscaryn."
Another element of the Houses is their racial background. Most of the leading houses are Sun Elves, while others are High or Sylvan or Wood elves. While it is never discussed in polite society, there is a hierarchy among the sub-races, with the Sun Elves seeing themselves as superior, then the High Elves followed by Wood Elves.
The Sun Elf houses are Elenereth, Velaethyn, Hani, Triscaryn, Rallad, Serken, Eildar, Tonmass, House Voronna, and Eassar
The High Elf houses are House Inglor,  House Lucaryn, House Iarlen, House Thardin, House Tythal, House Duanis, House Ansren, House Allaste and House Firlian
The main Wood Elf house is House Aerabrar.
House Elenereth is the leading house in the Kingdom, by virtue of being the house of the High King of Eridane for over 2000 years.

---

Etymology:
Arnosti Eridā́neva - “Noble Houses of Eridane”, using Prodatean pl form of arnost "noble house" (q.v.) and the Q possessive case -va, as noted in Eldamo.org: “Thus the “possessive” also has an attributive function: alcar Oroméva “Orome’s glory” indicates this glory that is a permanent attribute Orome, whereas alcar Oromeo “glory of Orome” would indicate glory originating from Orome in a specific moment only.” Since the noble houses are seen as a critical and permanent part of Eridanean society, it makes sense to use the possessive (permanent) form rather than the (impermanent) genitive ending (which would be Arnosti Eridaneo)