Dragonmarked Houses

Every dragonmarked house has traditions and secrets. Here's a few facts that apply to most of the houses:
Enclaves. Most dragonmarked houses maintain enclaves in major cities. These serve as strongholds and hubs for house businesses. A city may also have any number of businesses tied to the house, but these are simply providing services and don't have any direct connection to house leadership.
Names and Ranks. Any heir of the house who develops a dragonmark is allowed to add the d' prefix to the house name: for example, Merrix d'Cannith. Despite the Korth Edicts' proscription against house members holding noble titles, regional leaders within the houses are called barons. Most houses are led by a matriarch or patriarch, though some are led by a council.
Emblems. Each dragonmarked house has an emblem, a distinctive symbol that features on their heraldry, official seals, crafted goods, and anything else that warrants the house's stamp of authenticity. Each house's emblem appears along with the related dragonmark on the following pages.
The Twelve. The Twelve is an organization that facilitates cooperation among the dragonmarked houses.
Excoriates. Excoriates are dragonmarked heirs who have been cut off from their houses.
Foundlings. Foundlings are people who have a dragonmark yet have no tie to a dragonmarked house.
Test of Siberys. Dragonmarks manifest around adolescence. Each house puts its heirs through a trial called the Test of Siberys. The specific trials vary by house, but they place the heir in circumstances where they are likely to manifest the mark, if they have it. About half of the members of a bloodline manifest the mark.
Korth Edicts. The Korth Edicts prevent the houses from owning land, holding noble titles, or maintaining military forces (with an exception for Deneith). The edicts were established when the Five Nations were united. Today, many in the houses feel the edicts have become obsolete in the wake of the Last War.