“My wife,” he groaned, testing the mettle of his chains for the first time. “Iëva!”
“Has committed...” one of the ancient mouths warbled.
“Such crimes...”
“What was her price...” he coughed. “Tell me!”
“She sheeks only...” the bloody one bubbled.
“To save her soul...”
This is a quote from Chapter 1 of TUC. Indeed, it had me thinking of why did Iëva betray? After reading that part, I thought she traded Nau-Cayûti for "salvation" but then I stumbled back upon one of Akka's dreams:
Through closed eyes he watched her, Ieva, his wife of seven years, scurry naked to the cabinet across their spare room and produce a philtre, which she considered with an expression hung between terror and gloating. She turned to him, her face thin and cruel.
"How she will weep," she growled, "the filthy whore... And I will see it, and savour it, the breaking of her heart when she learns her beloved Prince has died in his wife's arms!"
He tried to call out as she leaned above him, holding the black tube with medicinal care. But he was sleeping and could not move.
"But you will not die, my heroic husband. Oh no! For I will fall upon your corpse, and I will wail-wail-wail, claiming to the Bull Heavens that you demanded to be buried rather than burned—like a Nonman!"
He tried to spit the foul liquid she poured between his teeth. He tried to reach up and out, seize her pale neck...
"Oh my husband!" she cried in a whisper. "My dear-dear husband! How could you not see the grudge I hold against thee? But you will know it, soon enough. When you are delivered, when you are beaten and broken—then you will know the compass of my spite!"
She doesn't seem very concerned with her soul here. She seems very concerned with someone else, so I went back and dug up this:
Then, in 2140, Nau-Cayûti’s beloved concubine, Aulisi, was abducted by Sranc marauders and taken to Golgotterath. According to The Sagas, Seswatha was able to convince the Prince (who was once his student) that she could be rescued from the Incû-Holoinas, and the two of them embarked on an expedition that is almost certainly apocryphal. Mandate commentators dispute the account found in The Sagas, where they successfully return with both Aulisi and the Heron Spear, claiming that Aulisi was never found. Whatever happened, at least two things are certain: the Heron Spear was in fact recovered, and Nau-Cayûti died shortly after (apparently poisoned by his first wife, Iëva).
So, the Mandate are almost certainly lying. Aulisi did come back and seemingly, it drove Iëva to murder Nau-Cayûti. Or did Aulisi directly drive Iëva to it? Perhaps she was made into a sleeper agent? Is that perhaps why the Mandate pretend she was never brought back from the Ark?
Also, it is clearly premeditated that she would deliver him to the Consult, by not allowing him to be burned, so there must be more than just vengeance toward Aulisi and Nau. Perhaps the Consult offered her shelter from the damnation that would surely come from exacting such vengeance.
[crackpot]Lastly, possibly purely coincidental, but Aulisi's name is nearly an anagram of Aisralu from Four Revelations. Interestingly enough, changing a U to an I. Possibly a connection that Aulisi is part non-Man? Is this why Iëva seems to angrily put "like a Nonman!" into her admonishment of Nau?[/crackpot]
Sound off and let me know how far off I am.