|A Meeting of Parley|
Parley. Not something most players ever use. apparently, Gary didn't think much of it either as there is only a paragraph in the DMG (p. 63). To wit:
Parleying:Upon encountering another party, the party with initiative can alwayselect to attempt some form of communication. This can be a friendlygesture, a throwing down of arms, offering of treasure, or some spokenword or phrase. Just what this effect will be is determinable only by theDM considering the prevailing circumstances. It is safe to say that a groupof elves attempting to parley with a red dragon will find their effortsgenerally unsuccessful unless they also have some obvious advantagewhich the dragon is aware of. It is common for player characters to attackfirst, parley afterwards. It is recommended that you devise encounterswhich penalize such action so as to encourage parleying attempts -- whichwill usually be fruitless, of course!
The last sentence is not one of Gary's best. Why should parley "usually be fruitless?" Not always, but occasionally it should work and work well. To penalize the players for not parleying and then penalyzing them for parleying is, well, dickish. It's like a game of oneupmanship.
Does that mean that a parley, especially with evil NPCs, should turn into a mutual admiration society meeting? Not by any means; expect the evil characters (and the players too!) to try to jockey for their advantage, possibly stabbing the party in the back just before the conclusion of the pact. I could see a cleric or cavalier of Hextor teaming up with a mostly good party to fight the return of the Temple of Elemental Evil in Hommlett. Said cavalier might be evil but he would have more in common with a Lawful Neutral character than with a Chaotic Evil one. Sometimes, there truly ARE greater evils!