The Three Sisters are also a trio of volcanoes in the Cascade Mountains of Oregon: http://en.wikipedia.org/wiki/Three_Sisters_(Oregon) Uller...didn't H. Beam Piper write about Uller? *googles* Aha, yes, the book was titled "Uller Uprising". Could be a coincidence, though. I also find it hard to believe no one has yet mentioned the Melisande character in Jacqueline Carey's Kushiel series.