I'm watching the dev stream from last week now and I'm at the point where they talk about how the player having a weaker military makes the Iridium take a more hostile stance towards them, and I had a thought. I don't know if it's too complex or anything, but I'd like to see how a rival civ responds to something like that be effected by the disposition of the civ in question's ruler and/or ruling class and/or public. So for example one rival might respond to you having a more powerful military than them deferentially while another might be spooked by the same power differential and get into an arms race against you and/or seek to build a grand coalition against you etc and another might appear deferential while working against you behind the scenes. And one might respond to you having a weaker military than them by seeing you as an easy target for conquest while another gets all protective, etc.
It would also be kinda cool if the disposition of civs - or of societies, ruling classes and individual rulers if they were going to break it down like that - changed over time, whether suddenly in response to events or more gradually.