To answer your question, Alkonium, yes, anyone may play as a non-Reaver. In fact, Reavers are highly uncommon in my fantasy setting--about 1 in 100.
As for a plot--*sheepish grin* I humbly admit that I thought up the concept of a "Reaver" character before I thought of any plotline involving them. In retrospect, this may not have been the best of moves, but sometimes you can't control WHEN you think of certain ideas--simply that they COME to you, and that's that. So, seeing as I'm at a loss for a plot, I'll go with the simplest one: Reavers haven't been around for too long. They're "new on the scene," as are their powers, and they're trying to find out how and why they need to draw upon their sources of energy. Basically, they're trying to find an entity known as the "Prime Reaver", the very first one that ever existed.
They believe that the Prime Reaver can give them answers, even though most people say that Reavers--and their progenitor--are a fearsome myth. The Reavers themselves know better, and several of them go on a quest--a pilgrimage of sorts. Analogies in real life would be faithful Catholics going to see the Pope, a Muslim's journey to Mecca, or a seeker's search for God via reading and participating in many different aspects of faith and spirituality.
The thing is, though, that none of the Reaver characters know if the Prime Reaver really does exist, and in the meantime, the priests of the realm are trying to capture and/or kill them a la the witch hunts of medieval Europe. The priests worship one deity figure only, whom they call the Arbiter. They see their god not primarily as a creator or life-giver, or even as a father or mother. They view the Arbiter as a strict judge of mortals and their behavior. Once upon a time, the priests say, mortals never broke the moral law and always behaved fairly toward one another, but then they transgressed. Now they must pay, with their fear and worship if not with their very lives.
The Reavers, say the priests, are a sign of the end of the world. In their holy book, there is a prophecy that states, "In the last days, mortal men will assume the powers of gods, and will seek to usurp the Arbiter and his throne."
That is why the Reavers are so feared and hated among the populace at large, because how would you feel if one of the Four Horsemen of the Apocalypse was alive and at your door a'knocking?
So, in flight for their lives and in search of the truth behind their new powers and state of existence, the Reavers seek out the one being who might be able to help...To this end, even several brave non-Reavers have come to their aid.
If this sounds interesting, please join! If not...what are your ideas?