suspendinlight
Prince
Just noticed this one. Apparently the game allows you to ask an AI to make peace with someone's vassal even if the master civ won't make peace with them. Let me explain with an example:
Bismark is the master of Isabella. Both civs are at war with Tokugawa. As seen in the picture of Tokugawa's diplomacy screen, I can ask him to make peace with Isabella, even though the option to make peace with the master civ, Bismark is red ("We'd love to but you'll have to talk to them..."). Since the master controls all diplomatic relations, I would think this is a bug.
Bismark is the master of Isabella. Both civs are at war with Tokugawa. As seen in the picture of Tokugawa's diplomacy screen, I can ask him to make peace with Isabella, even though the option to make peace with the master civ, Bismark is red ("We'd love to but you'll have to talk to them..."). Since the master controls all diplomatic relations, I would think this is a bug.