The Rethwellan royal family, House Jadrevalyn, has both Mage Gift and Earthsense in their blood. Traditionally, Rethwellan's rightful ruler is chosen by the Sword That Sings, and is bound to the kingdom with an Earth-binding.
The Sword was stolen, and for a few generations Monarchs were chosen by vote among the royal family and others of high rank. Tarma and Kethry found the Sword and returned it to Rethwellan, where it promptly selected the new king.
The first King of Rethwellan was an Adept-class Mage from the Leverand mage-school, and he valued honesty so highly that he ensorcelled the royal archives so that once something has been entered into the royal archives, it cannot be removed or "something nasty happens."
A list of Rethwellan's monarchs is available here: Monarch
It is stated that Rethwellan is sufficiently opposed, religiously, to homosexuality that shay'a'chern are not only unwelcome, but sending an openly shay’a’chern envoy with his lover as an ambassadorial unit might cause a declaration of war from Rethwellan for the perceived insult.