Julien,

To summarize:
1) There's no cooperation among players.
2) There's no staff.
3) There's no coded structure.

You, my friend, have just created the perfect rock and hard place in RP MU*s. Granted, I realize it's hypothetical, but without any of the three items above that roleplaying environment is going to sink faster than a paralyzed hobbit who's allergic to water.

Even in my days engaging in freeform roleplaying on the IRC, there were specific 'rules' set up to discourage situations such as the one you outlined. There were operators of the channel as well, who could kick and ban any that refused to follow them.

In the end of it all, that's the major purpose of both code and staff--to ensure the sanctity of roleplaying within a realm.

Best,
Edward

Read Thomas Hobbes, about his concept of the State of Nature. Great philosopher. It sounds very much like what you're proposing, and he uses it as justification for people banding together in lawful societies. Unless you're an anarchist or enjoy ooc manipulation and bullying to get your way, there really isn't a way to solve it. Unless you cheat and use peer pressure and social, non-written-in-stone laws.

My other response seems to have disappeared, so I'll try again.

About the only solution I can see (which isn't a great one) is to have someone else step in with some excuse to have one of them leave with him/her.  The person leaving can save face by saying something like "This isn't over!!"; I'm not sure what that would be other than saying someone else needs help, your house is burning, whatever. It won't solve the underlying situation, but it will get them out of the deadlock.

I think the biggest problem is that too many people believe that every confrontation has to end with someone dying or being beaten down in some other way.  Many times those conflicts can be acted out with no actual violence involved, so it doesn't matter if the other person responds as expected. If you're one of the participants, you have some control over it; if you're just an observer, you can always try to find some way to end it without having to rely on either of them being the `bigger person' and accepting defeat.