From Introduction:
The last of the Ardoussarlian kings, Torvin XIX, has seen his mainland possessions dwindle until all that is left of his kingdom is Inkstvarr, an island in the North Sea. He believes he can turn his fortunes around, however, by hiring on some arcane help. Valkolov the mind-wizard has come to his court, bringing her flying castle with her and tethering it to the island. The court is nervous — as all sane people are, when confronted by sorcery — but there are also supernatural problems occurring on the island, so protestations have been minimal.
Valkolov is the last known arcanist to inhabit one of the flying glass castles that are normally found above the Plains of Akkad. Every other wizard has disappeared, but Valkolov took her castle and moved away instead. Though she rarely speaks of it, she is deathly afraid of the purple clouds that sometimes envelop the castles. The more research she does into the disappearances, the more paranoid she becomes.
Providing aid to King Torvin is a way to give her some small amount of security, insulating her from the mundane world of politics and war. But she is far less invested in his welfare than he thinks she is. He sees parallels between them — the last of a long line of kings, the only remaining wizard with a flying castle — but these coincidences do not assist her magic, so Valkolov attributes no special meaning to them.