Over in Cameron's blog on mindless killing, Potshot made an interesting comment:
I would love a bunch of NPCs to say, “well you three can pass, but not the Dwarf! He killed Arglebargle! Get ‘em boys!!”
Before reading that, I had never considered players with different faction standings being grouped and adventuring together. Of course, it seems so obvious now!
It's possible to introduce a new dynamic into gameplay: group influence on faction standing.
"No, it's alright. He's with me." That's basically the sort of feature I'm talking about. If your faction standing with the Freeport Guards sucks, they might still let you through the gate without any trouble if you're grouped with three or four players who have good standing with that faction. If your standing with them is really terrible or your groupmates have only neutral faction with the guards, then they'll still bar you from entering the city.
It could work both ways, of course. If your groupmates forgot to tell you that they killed a few of these guards last week, you might be in for a nasty surprise when the guards come after you as well.
There's a lot of gameplay that's made possible by this sort of system.
Perhaps you have very little chance of earning enough faction with the royal family to go where you want in the royal palace (possibly to reach a quest-related figure). If you can ingratiate yourself with the right NPC with some relationship to the royal family, you might be able to accomplish your goal indirectly. Perhaps you make a friend of a palace steward when you see him in the market square. Then you can walk with him back to the palace; the palace guards watch you suspiciously, but they don't say anything while you're with the steward.
That little adventure could be complicated in any number of ways. Perhaps the steward needs further convincing once you're inside the palace. Perhaps you need to leave the steward's company once inside to find what you need, then find the steward again or sneak past the guards (easier to do when they're focused on people entering). Maybe the steward changes his mind once he sees what you really came to the palace for, and he calls the guards.
Anyway, what else might be done with this system? How might you tweak it?