Cass took a second to realise how worked up he was, and how easy it had been for Fiona to get him there. It was completely understandable. He had attempted, naturally or unnaturally, to put a barrier between his emotional state and the hell that was this dungeon.
That hadn't worked out well for them as soon as they encountered the true nightmare of this room, and Cass learned how fucking devious the demons actually were. He should have known better. The gods hated them, and Cass could only think of two reasons as to why the gods would hate them.
They were either the complete opposite of the gods, or they were just like them. Cass had hoped for the first, but was becoming uncomfortably aware that it was the latter.