From SWIMMING WITH THE UNDINES, Excerpt #5:
Who is the Domnicellae, the high priestess of the Pelerines that Severian meets only once, the encounter taking place in the tent cathedral after he and Agia have crashed into and destroyed the altar of the Claw? Her name is never given (usually with Wolfe a sign we're meant to figure it out), and when Severian later convalesces in the lazaret of the Pelerines, she's conspicuously absent--simply "away, as Mannea, mistress of the postulants, tells us, with no reason given for her nonpresence. Does author Wolfe provide us with any clues as to who she may really be?
I believe he does and suggest she's Thecla's childhood friend, Domnina, whose tale we first hear from Sev in the Jungle Garden. For starters there's her name, which can be extracted from the letters of Domnicellae; as I argue elsewhere Wolfe uses this device a number of times in the Book of the New Sun, where names are either nested inside larger names or derived via near anagrams from the parent word [1]. In addition, the witchy priestess has the stature of an exultant, the class we know Domnina belongs to. And as for her being absent from the field hospital of the Pelerines, this is Wolfe cheating a bit; Severian, having incorporated Thecla's memories via the alzabo, would no doubt recognize her old childhood friend, and so Wolfe very conveniently has her missing. Finally, we have young Domnina's experience with the numinous, a fish of light caught in the mirrors of Father Inire--about as potent a Christian symbol as you could hope for [2], but also calling to mind Severian's eventual turn as the piscine Sleeper, the Oannes-like god of Ushas. The encounter apparently disturbs young Domnina quite a bit [3] and doubtless leads her to revaluate her situation, nudging her toward a life spent among the Pelerines, and eventually culminating in her rise to the rank of Domnicellae.
[1] Zak from Tzadkiel is one obvious example of this. Another slightly less so is Camoena from Cumaean.
[2] Ichthys, of course--the Greek word for fish--is an acronym for Iesous Christos Theou Hyos Soter--Jesus Christ, Son of God, Savior. And early Christians often used the fish as a secret sign to identify themselves.
[3] Or so it seems from Sev's description of Domnina after the fact: "She found herself in another world, and even when she returned to Thecla she wasn't quite sure she had found her way back to her real point of origin." (SHADOW, Chapt. XXI)
Robert Borski