Out-of-Character Discussion

Gryndorf is optimistic, and I want advantage on convincing a NPC that nothing bad will happen with our plan, and they should go with it for X, Y, and Z reasons. My persuasion roll now gains advantage, and my "stress marker" gets checked off.

I cannot use my inspired action to help Gryndorf, unless I can justify how that behavior fits my personality trait in some way.

I can also apply a setback, saying that Gryndorf's naivety does not allow him to appropriately know the motivations of the merchant he is negotiating with, and willingly take disadvantage on the insight roll.

Now, if Gryndorf's "stress marker" tracker is full, I now have to notify the DM of said event. The DM puts that in his back pocket, and later on, while we are at a crucial chase in a maze, and the party is running from a pack of minotaurs, and Gryndorf arrives at a crossroads in the maze, the DM may pull out a "stress setback", where Gryndorf has a mental crisis and he doesn't trust his own judgment for a time, resulting in disadvantage on wisdom and intelligence saving throws for the rest of the session.