The noble Tiefling houses have ruled over the Dominion for centuries. The ruling houses, or clans wield unchallenged power. Each house rules one of the main cities of the Dominion, but they have bases in every one, and frequently travel from one to the other on matters of trade or politics.
The clerics of the Overseerteach that the Tieflings are descended from the first tribes to be united and cast off their primitive barbarism, but men in their cups say that the power of the tiefling houses is not wholly natural. Some brave few even claim that long ago, the tieflings were men who made dark pacts with darker powers, exchanging temporal power for … well, no-one knows for sure what. Some say the tiefling’s decidedly fiendish looks are the downside of that long-ago bargain, and some say they paid a darker price still. What is known is that their power is to be respected, and their wrath feared.