Keltham sets aside that particular confusion as probably the wrong kind of incredulity; there's something serious about Carissa's words. Not her tone, which sounds the same as always, but the actual semantic content of them.
"You might have a better idea of what I'd desperately want sexually than I would. The most recently discovered part of my sex drive, that's never had a chance to satisfy itself before, is something you told me about, after all. And several times, I've felt like I've been making some kind of misstep with it, which I've been telling myself is fine for a first discovery of it -"
"But I - don't understand - what you mean by saying that a symmetrical bet isn't Evil. You bet because you expect to win? Maybe some people aren't like that in the cuddleroom, but I sure am - I mean - what version of this practice is asymmetrical, Evil instead of Neutral -"
"You can't just mean, what, that we pick something with even odds and - bet an hour of oral one way against two minutes the other way? Wouldn't that be less Evil for you, even if it was more Evil for me? Taking things without giving in return, isn't that - I mean, isn't that - a smaller version of Abaddon, basically?"
The part of Keltham that never stops observing himself notices that his voice is questioning, possibly frightened, more than trying to contradict her. He's lying on a bed looking down at a naked Carissa with her head not very far from his still-erect penis, and part of him feels like he's standing on a very narrow ledge with somebody who might be about to either stabilize him or push him off.