Protagonists in conflict with antagonists? Wow, what an astonishingly original idea!

Sarcasm aside, I'm interested in developing a roleplay in which the players are divided into two factions, which are in direct conflict with one another. The idea of the division is very simple: One faction plays the part of the stereotypical band of Tolkien-ripoff questing heroes we know so well (henceforth known as the Chosen Ones), while the other is a somewhat more ragged assortment of miscellaneous scum and villainy, who have reasons to dispose of the Chosen Ones, and resources with which to do it (let's call them the Dark Lords). The scenario is intended to be a fairly generic high-fantasy Magicland, though at its heart the idea could be easily adapted to other genres. Likewise for the story, at least on the surface- Hypothetically, if a roleplay like this gains momentum, a more subtle, less clear-cut storyline involving both factions could be gradually developed. Possibly.

Back to a point, anyway. The idea here would be for the characters to develop a lot of inter-personal drama, at a fast rate, with the actual story not being the priority roleplay-wise. Slow in-game time would not work well here, except in combat scenes between player characters. The Chosen Ones would move around quickly, stay at unnecessary locations only briefly, and encounter their opponents regularly. Meanwhile the Dark Lords would meet often and keep themselves very busy indeed with obstructing the path of the Chosen Ones, and quite probably often deal with problems of their own, likely coming from some omnicidal third party. A theme I'd like to achieve is for the characters to be in constant, indirect interaction as well as direct interaction, because all actions have hidden consequences, and these characters are all going to be wrapped up pretty tightly in the effects of each other's decisions. If a tree falls down in the woods, it doesn't just influence the Chosen One it crushed as it fell and their allies, but also the Dark Lord who intended to use it to summon a tree demon, the Dark Lord that suggested the demon in the first place, the tree-hugging Chosen One who swears vengeance, the third party that was using the tree as an outpost, the magical beaver who weakened the tree and later offers his services to the Chosen Ones as an apology, and pretty much everyone in the entire roleplay. That's probably a laughably bad example, but the point is that everything the players do may hopefully have some effect on other players.  Yes, all this will mean time-skips and OOC planning galore, but again, we're developing the characters, not the story.

While we're at it, there are plenty of other mechanisms that can hypothetically be used here. We could push the entire roleplay into a sci-fi or other genre direction. We don't necessarily have to make the Chosen Ones and Dark Lords representatives of good and evil, respectively. Moral ambiguity is dramatic and fun, and each character can have their own motives. The possibility of a third party of NPC meddlers could be taken to a lot of interesting places, as can the question of why the COs and DLs are in conflict in the first place. This idea isn't thought out at all yet.

Continuing from that point... I came up with this idea probably sometime within the last hour or two and typed it from a 3DS just now, and as you can see, it's barely ready to start OOC work on yet. What I'd like probably more than interest statements right now is criticism and collaborative work on the idea. I'm technically the GM, but if anything happens to this idea, I want it to remain player-centered and player-built. So, lovely reader, for now let's just take a look at this deformed duck and tell me how I should butcher its genes to turn it into a magestic swan, ok? Ok. Goodnight, let's hope I'm sane enough to scrap this idea in the morning.