So I have been re-reading passages from the GO and the UC.
And I am trying to put everything together.
Kellhus goes mad during this circumfixion which breaks his spirit and allows the agents from the Outside into his mind.
Initially he thinks it is the No-God who speaks to him, for whatever reason. Maybe the influence of Achamian, the discovery of the Consult and so on.
Then he says that he learns to ignore the voices in his head.
"He suffered visions, certainly, but he had long ceased to trust them".
GO, p. 121, Chapter Aorsi (hard pack version)
We know that during the Unification Wars, Kellhus studies Daimos and he walks in the Outside and he comes back. Presumably during this time, he makes the deal with Ajokli.
But maybe Ajokli being the trickster god, cheats Kellhus into thinking that he is the God of Gods.
My impression is that when Kellhus reveals to Proyas that the God of Gods is the antithesis of love and that he cares not, and says that the damnation of mankind is the granary of the gods, Kellhus has in mind Ajokli, but he does not know it.
I mean this is the trickster god, surely he could trick Kellhus.
Kellhus labours under the impression that he has some deal with Ajokli-who-pretends-to -be the god of gods and proceeds with his Great Ordeal. Possibly he is under the impression that if he vanquishes the Consult and its allies, the god of gods will somehow reward him.
This line, the living should not haunt the dead is inserted a few times.
Kellhus says to the Dunyain allies of the Consult that he is an inverted prophet. This echoes his conversation with Proyas, where he says a prophet brings word of mortals to the gods.
"Then what is their purpose?"
"Is it not plain? To deliver word of Men to the Gods".
GO, p. 122, chapter Aorsi.
"I bore word of the temporal to the divine"
UC, chapter the Golden Room, p.415
Right until that point Kellhus is in control.
But then Ajoklis takes over, he is the trickster god and more importantly he reveals to the Dunyain that basically the Ark is the deepest topos on Earwa which allows him to seep through and take over Kellhus.
"Because in all the World, no place has witnessed more terror, more obscenity, brutality, or sublime trauma. Your Golden Room is scarcely more than a bubble floating upon the Transcendent Pit. Hell, my brothers. Hell pollutes its every shadow, smokes from its every surface, creeps through its every brace..."
UC, The Golden Room, p. 421 ( some italics were removed but you get the gist).
It is quite conceivable that Kellhus had a different plan altogether from Ajokli and in the end Ajokli is the one who gets undone.
Kellhus was perhaps under the impression that he would somehow strike a bargain with the gods. I will terminate the effort to shut the world, because if the Consult is successful the gods will lose, but in return the living will not be claimed by the gods or something.
And this is where my thought fails me but without having a clearer picture of the metaphysics of damnation is hard to tell what a possible bargain between Kellhus and Ajokli would look like. But we should not exclude the possibility that Ajokli manipulated Kellhus.

Thoughts?