Book of the New Sun: Agilus

"The new customer was a youth whose face was hidden in an inlaid close helmet, of which down-curving and intertwined horns formed the visor. He wore armor of laquered leather; a golden chimera with the blank, staring face of a madwoman fluttered on his breastplate."

-The Shadow of the Torturer, chapter XVII, "The Challenge".

Agia is Agilus's sister, and is the book's stand-in of the femme fatale. Severian's vengeful nemesis.