Someone just posted a link to a guide to how to bring peace to Revaire: https://docs.google.com/document/d/17P7Q0qq6xIPYoGJYAAzh1RH6SLvRHKFvjd7jSAfGxXU/edit
I managed to stumble upon it after banging my head against the wall before the guide, but I think it has to do with persuasion as well? I didn't keep track of the choices I picked, but I think I picked the same choices more than once and I noticed that the option for peace showed up only once I had a high enough persuasion. I can't confirm if that is really true though since by that point I was so relieved that I didn't want to go back and reload to see the difference in stats 😂