Although I have a general idea for how the Character system would work, which allows for functioning espionage and politics, one issue is that of player response. Essentially, even if the system is very functional I must be concerned with player perception. If the players decide the system isn't fair, there's not much I can do.
Essentially the goal is to have espionage and diplomacy work in a similar manner to warfare. Well, better than most warfare since most warfare is all about doom stacks and what not. Basically you should need to engage in various different activities some long term like building up spy networks and some short term like helping out a neighbor in a time of crises or w/e. Spy networks will expose information about enemy characters including their desires and their actions. You can have general spying, put tails on specific characters, etc. Some spy actions will involve non-existent people. If you bought a chambermaid's loyalty there is no actual chambermaid character in the enemy noble's court or w/e. If a character is engaged in a plot you might figure this out. More effort might figure out what other characters are involved with them and give options to bribe or turn them. Spymaster characters are the hardest to spy on. Early spying might reveal that they are spymasters to give you the chance to purposefully invest more effort in discovering what they are up to. You can engage in defensive spying as well. Put watchers on your king or noble or wizard or w/e. Enemies can discover watchers and make a choice as to what to do.
The things you can uncover vary. As mentioned in previous threads you can discover explosive secrets that are brought into being by the game world. The example I believe was a dragon worshiping society where the ruler imprisoned a dragon and drew dragon characteristics and power from it into himself to become the ruler. You could find his secret, and interact with him in various ways as a result. Less interesting secrets are possible as well. Another previous example is the noble who dotes on his daughter and wants her to marry someone who will love and care for her. This secret merely allows you the chance to being the slow process of binding a noble house to yourself, or maybe not depending on the feelings of the male heir. W/e. But lower stakes in any case. Turning spies or exposing plots is another important but still lower key discovery.
Now of course we get to the hitch in the plan. How to handle this mechanically. What you discover will probably be random to some degree. How else to do it without real social interactions? You can focus on specific characters, plots, or w/e but still you'll have some randomness.
Were you just about to diffuse the plot but then it went off? Will the player blame that on a bad role? How will they feel about spending a lot of effort and failing? Well, not a LOT of effort, but some. How much complexity can go into a single espionage event chain?
How can I keep espionage powerful enough for people to play a nation like say, Mayene from the Wheel of Time, or play like Lord Baelish from GoT, or perhaps something like the Lords of Waterdeep? Though that last example also includes some strong economic game play I'd imagine.
The struggle is real my friends. What do?