Mogg, given your list of PCs I have to ask if this is a continuation of previous campaigns or are these PCs created for a new campaign? That will affect how this starts. (Personally, I always find it best to come up with the campaign first then have the players build PCs for it with some minimal amount of direction. One intended privateer themed campaign w/o any PCs who were worth 2 cp on a ship was enough to learn that lesson. But then you didnt ask for our opinion on that.)
However, some ideas that might work for either case:
- A small cabal of demons, devils, eladrin, and angels want if not an all out end to the Blood War then at least a cessation of overt hostilities for a century or three. Enough time, they believe, for their respective factions to gain some sort of advantage, or for some more personal reasons. None of them trust each other, of course, but they have managed to come up with enough of a plan to get things going. They intend to hobble the war efforts by removing resources and objectives equaly from each side in the conflict, then use political influence to suggest a temporary cease fire. Because they do not trust one another none want to risk their more valuable agents, but neither do they want to send completely useless agents either. They need capable but expendable. Enter the PCs. Each of whom should have some reason for working for one member of the cabal. They are told to work together, but keep an eye on each other. Overt hostilities will not be tolerated by their patrons. The PCs may also learn in the process that they are neither the first such group no the only one currently in play by either the cabal or members thereof and should eventurally learn thats what is best for their bosses may not be best for the PCs, giving them more reason to have no one but each other to trust.
- A little less well defined but essentially the same idea takes a page from Marvel Comic's Exiles. The PCs are gathered by a person or person unknown that speak through a mediator. The PCs are told of a prophesy or prophesies to which each of them are at least tagentally connected. If they perform certain tasks they are guaranteed futures they will see as at least good if not ideal while if they refuse, or if they fail, neagtive thigns will happen (For the CG elven healer, for example, if she helps and succeeds a particular lost elven city will be recovered by a kinsman where as if she fails the same kinsman will perform the wrong ritual an unleash a plague that will wipe out all elves in a generation. For the tiefling it can simply be a matter of great personal power or a bad end.) The PCs are given some item that helps them know what to do to influence the paths of fate, but information is often cryptic or less than specific. They should be able to both interpret the directions and complete the missions successfully, but if they follow the wrong course they should face or at least see the consequences.