Question 1: Are they being honest with him, or not?
Subquestion 1.1: What motive do they have to lie? In a dath ilan master-criminal story, the obvious answer would be 'lure you into doing something awful and then blackmail you about that', but Cheliax really does not seem to be in that sort of situation.
...and now the tree isn't branching further. Keltham is having more trouble than usual thinking about this. Part of himself is recoiling in horror and it's not because the situation being described sounds awful for Carissa, it's because something about it seems terrible and threatening for him.
Is it that he distrusts himself with power?
Is it that he's afraid of pressuring himself into doing something to Carissa that he didn't really want to do, even if she turns out to want it?
Is it that the ENTIRE FUCKING SITUATION IS MANDATORILY ILLEGIBLE WITH NO CAREFULLY OPTIMIZED MESHING GENDERTROPES AND NOBODY IS ALLOWED TO NEGOTIATE ANYTHING IN PLAIN BASELINE?
"How do you know the contents of Carissa's mind in such detail?"