Unfortunately the Book of Perfect Balance could only concern itself with True Neutral, since LN and CN are imbalanced on the L-C axis. Personally, I find LN and CN to be the most interesting characters to play, with N coming in tied for third with CG. So I'd like to see a treatment of LN, TN, & CN, even if two of those arn't in perfect balance.
As far as Neutral could go being its own force, I think perhaps it would work against Good and Evil on the principle that the forces of Good and the forces of Evil are allowing their passions to overcome them. The Neutral force in the world would strive for dispassion, objectivity, and impartiality. I think those are distinct from "Good's" search for Justice and Evil's search for Dominion.
As far as Neutral could go being its own force, I think perhaps it would work against Good and Evil on the principle that the forces of Good and the forces of Evil are allowing their passions to overcome them. The Neutral force in the world would strive for dispassion, objectivity, and impartiality. I think those are distinct from "Good's" search for Justice and Evil's search for Dominion.
