wait you need to declair an action to use your passive score?!? where are you getting that from passive is the opposite of active.Generally, passive Insight is going to be what is used when it comes to noticing whether the NPC's body language or mannerisms suggests something about their agenda, intentions, or truthfulness, if it's appropriate to use a passive check at all. But again, a passive check is just a special type of ability check. And for there to be an ability check, the player must have declared an action for which there is an uncertain outcome and a meaningful consequence for failure. When it comes to influencing a PC, there's no uncertainty as to the outcome, so no check, passive or otherwise, is appropriate.
unless there is uncertainty... no one (that I have seen) is argueing to roll every sentence, every step, even every climb... (and since I house ruled to make MORE things automatic not less god knows I haven't)I think where some get twisted up on this is that they feel the need to roll dice when an action a monster takes smells faintly like it aligns with a "skill check." The monster lies to the PC, so they must make a Charisma (Deception) check. The DM here is failing to consider the rest of the adjudication process which, if they did, would tell them they can't proceed with that check because of the lack of uncertainty as to the outcome.
OKay and if the PC and DM are UNCERTAIN becuse there is not a guide line and the acting/story telling ability of the DM/Player isn't in quastion but the character's skill?What should happen therefore instead is the DM simply presents the lie to the PC and it's now up to the player to take action to determine whether that's the truth or not (or, alternatively, is persuaded by the NPC or intimidated).