 Lamia and her sister (unnamed in the novel, but given the name Tristesse in its sequel, "The Serpent Mage") are human women, once David Clarkham's wives.After Clarkham was defeated in the war he started, he abandoned both women, and the Sidhe captured them, using their magic to horribly warp their bodies.They now live at the Isomage's old house, which stands on the gateway between the human and Sidhe worlds, which they guard, on the order of the Sidhe, who threaten to do even worse to them should they fail.