I don't blame them. The Twisted Rune is one of Faerun's secret organizations that actually is secret. No one knows who they are or what they want, and except for maybe Big Cheeses like Eliminster and Khelben, no one's even heard of them. (Also except for omniscient gamers. ^^') The leaders (at least, the leaders as high up as we've been told) are mostly very old, very powerful liches and demiliches. They were founded by Rysellan the Dark, and they generally have their dark hands in everything. Everything. I seem to remember that they have complete control over the government of Calimshan (I think), and they have all of the Zhentarim on their leash, though neither the Zhents nor the Calimshites have any idea who they're working for.
I just wish I knew how high-ranking a member Shangalar was... and what on Toril the Rune wanted with skinned peasants.
Oh, and Sekolah is the Sahuagin shark-god. I wasn't aware that his avatar ever was supposed to make an appearance in BG2.