I actually think the best PC-to-PC interaction mechanics are in D&D, or any other game, where you can’t use any mechanics to regulate your interactions with the other PCs. Mechanics are best thought of as the interface between your imagination and the fictional world. It produces fruitful friction (“undesired outcomes” as some put it) because you’re linking your real-life experience (the voices of your fellow players, the location of the minis on the map, whatever) to the imaginary experience. Whereas the interaction with your fellow PCs already has a far more fruitful, wide and deep channel to flow in – the real world. How about just try to persuade them and if you don’t persuade them they aren’t?

Just kidding, actually Smallville is best.