I would imagine that parlay would be easiest either before fighting breaks out, or after it ends. In the first case, bandits could approach, say "your money or your life" and the player can attempt to speak then. Otherwise, a fight breaks out and the player can use nonlethal attacks (sleep spells, stunning, paralysis, etc) and once an enemy recovers from that there is a window of time where dialog is possible. To end a fight with speech likely requires using something to temporarily get everyone into that state of letting you talk. Basically, knock everyone out with disabling spells, let them wake up, then talk to them to get them to stand down. Oe perhaps firing off a powerful spell "just to get their attention" will shock them enough to gain you a moment to start dialog.
the bandits part is planned. at the moment , i'm dealing with bushwhackers, badguys who whack you for your stuff.
forgot to mention, no magic or techno. caveman rpg. so no lightning bolt spells or firing off a couple rounds from your grenade launcher to get their attention.
but you can attack to subdue, then capture, which, of course, would give ample time to talk, once they're safely tied up.
so you think (and the votes on your response says other agree) that one should not be able to yield in combat as in Oblivion?
i could see that in the case of bushwhackers, they're out to kill you right off the bat. but what about thieves, when you've had enough, and will turn over your goods? or fights that start with accidental friendly fire?