Literally the whole point of the Great Ordeal is to destroy the Consult and stop the No-God from being reborn. That the No-God was reborn is not a Deus Ex Machina in my opinon. (Well, it's not in the literary sense at least. In the literally sense, yes.)

I also don't find it hard to believe that the Consult would take Dunyain prisoners. Clearly Kellhus has enormous power and understanding the root of that power would be a tremendous benefit when it comes to defeating him. And what is five prisoners chained up in the basement gonna do? We have all the science and magic in the world at our disposal, and you are worried about a couple of powerless prisoners? Absurd! Well, knowing the Dunyain and with the power of hindsight not so much...

I think there is a reason there was a whole storyline on how people found the existence of "thought-dancers" so hard to believe. The also showed us scenes in the previous books where the Consult underestimates Kellhus and what he is capable of. Hell, as a reader I have been in his head and I still ended underestimating him several times, even though it seemed obvious in hindsight.

Kayûtas: I have to mostly agree with Jackehehe here...I thought he was a boring character for the first three books of this series. Nothing distinctive about him (unlike his siblings), he was basically a more human Kellhus, "Kellhus Lite", if you will.
While I agree he did have a role as a Kellhus stand-in to Sorweel and later Proyas, and was the tiniest bit more interesting to me by the end, I ultimately came away from the series with (almost) the same impression I had at the beginning. I guess that can be more of a subjective thing, though, as some people out there might like him as a character?

(From a maxed out thread)

I actually found him to be the most terrifying character in the books, and he adds a lot to the Proyas/Great Ordeals storyline. What makes that storyline interesting is how alone Proyas are and the enormous struggle of leading an army that also slowly goes insane while struggling to remain sane himself. I thought it was a huge turning point Kayûtas just murdered one of the lords, seemingly surprising even himself. His reaction also seemed to show that it wasn't a calculated decision and he that had gone crazy just like everybody else, leaving Proyas as the only semi-sane person in the Great Ordeal. Its a huge difference between having this superhuman on your team and having him as another lunatic you need to control, which seems like an impossible task given what Dunyain are capable of. As the story progresses he becomes this devil on Proyas shoulder, using his intellect to justify his insanity and actually making himself and others believe they doing the right thing. I think this is a far more horrifying portrayal of what an insane Dunyain could be than Inrilatas. Someone who not just heaps damnation upon himself but corrupts everyone with his superhuman powers of persuasion.