>>5180572>>5181575I'd rather not say if characters would or would not do X as this meta knowledge can influence your choices, but you can probably guess Daitza's reaction to you or Ruby proposing a threesome.
Some persuasion scenarios don't have a speech DC attached to them. This doesn't necessarily imply they're impossible to succeed in, but you'd need a sensible write-in, recur to previous knowledge or do more in conjunction to talk no jutsu. For example, trying to convert Suneyh to your side (a demon that feels no regret over his misdeeds and whose demonhood only elevates his already malicious nature) won't have a DC involved. Whether this means it's impossible or that it could be achieved with a write-in appealing to his (possible) relationship with Bloodseekers is up to you to decide.
Something to take into account is that persuasion doesn't always take effect immediately. There are times where people won't agree with you on the spot when you present them with an opposing idea, no matter what you say, but they might change their minds later after giving your words a thought.