See, I think Kellhus knows everything about the Zero-God and how to obtain the Absolute. I think he cares about humanity because he knows what awaits them in the Outside. But, you know, Thelli is right, Kellhus is whoever he needs to be at that moment. It what he has to do. He has to be a lying, manipulative S.O.B. because he is fighting a war not only with the Consult, but with the Gods. The TTT and how he took over an Empire and became what he now is, is all built on lies. It's what the Dunyain are, and Moe was Dunyain, Kellhus is more. I think there will be a scene with him and Akka in TUC where he explains all this. That he broke on the Circumfix, seen how his manipulations had killed an innocent, one he cares for. But he had also grasped the TT, and had no choice but to continue down that path to stop the Consult and the Gods. His actions are at odds with his emotions, but they have to be with what he has to do. That's why we only catch rare glimpses of them, because he cannot let them rule him entirely.