Infamously, Tarush Noptii is openly ruled by vampires. The quick version of their history is that some... thing fell out of sky thousands of years ago. Several heroic generals and their armies went to investigate. They were all slaughtered. The generals themselves were somehow corrupted by what they found, and became the Primogenitor vampires--twenty of the most loathsome creatures in existance.
Although they are, of course, somewhat secretive and keep their power close to the vest in their incessant power struggles with other Houses, it is believed that there are upwards of 200 vampires in the entire kingdom who owe some kind of allegiance of fealty to House Dracul, making them by far the largest of the houses, if true. Because of this, House Dracul is often forced to "go it alone" as their rivals tend to form alliances against them. Few prefer to deal with Dracul, since Dracul treats them constantly as if they approach them from a position of strength.
In addition to the vampires, House Dracul has an army of about 5,000 Untouchables, mortals who have pledged their service to the house in return for protection from vampiric predation for them and their families. These Untouchables are apread throughout the kingdom of Tarush Noptii and wear distinctive uniforms (and travel in platoons.) Because of their priviledged position, they are usually given a wide berth by the common people, who have a number of myths and rumors about what they are up to. It is widely believed that the Untouchables harvest non-Untouchable Tarushans for feeding. This is actually mostly false; the vampires of House Dracul all insist on hunting their victims themselves as much as possible, and only extreme circumstances of some kind or another will have a vampire "fed" by a captive brought to them by someone else.
In addition to their activities within Tarush Noptii itself, House Dracul is the "face" of Tarush Noptii to the outside world, and Tarushan embassies and official contacts between Tarush Noptii and others nations are almost always staffed by Draculans, often including one or possibly two vampires, a bodyguard of a score Untouchables, and possibly some other soldiers or mercenaries or other valuable workers of some kind. These expatriate Tarushans still serve the house loyally, but are also more pragmatic and more likely to enter into alliances with indivuals from other Houses if they happen to come across them, seeing themselves as not just representatives of House Dracul but also the entirety of Tarush Noptii as a whole.
This outward looking attitude has greatly increased the coffers of House Dracul relative to many of the other houses, even further increasing their strength and influence. In addition to the Untouchables, several thousands--numbers that are unknown to anyone other than the Dracul elders--of mercenaries serve their wishes within Tarush Noptii as well. In all things, House Dracul seeks to expand its own influence and blunt the influence of other houses. In response to the success of the house in opening embassies, some of the other houses have started opening communications with power groups outside of the nation of Tarush Noptii, but given the headstart and other natural advantages that House Dracul has, nobody has yet managed to parlay that into the kinds of benefits that House Dracul takes for granted.
In a d20 environment, I prefer to represent House Dracul with the eldritch template from Monsternomicon rather than the vampire template from the Monster Manual. Remove any reference or requirement related to being elfish (since of course there are no elfs in DARK•HERITAGE) and it works great as a less limited version of a vampire; one who is not unduly hampered by the sun--although they still prefer to avoid it whenever possible.