I do love me some Dark Souls.
The bleakness of the setting would be upset a bit by the fact that there are others joining the fight, unless they are all equally damaged in some way.
An idea, this is the beginning of a new age of fire, and this is the story of how civilization grows again. The remaining unkindled clear the way for actually peace to reign again. That's their purpose, and when the world is safe for the peoples to thrive, they'll have no place in it, having lost their purpose.
I agree with the bleakness(or eeemershun) being disrupted slightly with the group aspect. The 'group' aspect was added to make it slightly easier to have a decent group being feasible in Dark Souls. While you can Team up in Dark Souls, it's more of a play with your friends thing. The original concept for this was to have a small group (of no more than 5) and letting them decide their own path which directly influences the world. I.E, player 1 lights a bonfire, that bonfire is now open for all players or Player 3 blows up a bridge(which isn't possible but this is an example), depending on which side of the bridge he is on, either no one can now access the area or only he can. Would that be a better setting?
AS for that idea, I'm quite frankly in love with it. And let me pull my n00b card realllllllll quick....