Found a possible oversight with the Deionarra dialogue in the Mortuary. When she asks you for a promise before telling the prophecy, you can reply (among other things):
#1 (Charisma check) "I find it hard to believe that a woman I once loved would blackmail promises from me with the promise of revelations. Have you no faith in me, Deionarra?"
#2 "The price of such a promise is too high."
If you reply #2, you get taken to another set of replies, including #1, but without the charisma check.