Somebody shared a very good article on Facebook a few months back about how Avon fits the template for the modern TV protagonist -- the cynical wisecracking nerd with poor people skills who prefers to sit back and make nihilistic jibes about the state of the world and the folly of thinking that it might ever be otherwise, rather than taking the risk of exposing anything that he actually believes in. Avon represents a society that knows far better than to trust anyone or hope for anything unselfish: homo economicus, who makes decisions in his own best interest. (Or, if you prefer, the Dwarfs in "The Last Battle", who are so determined not to be taken in by false promises that they no longer allow themselves to believe in anything good at all.)

It is very much easier to deride everything from a safe distance than to stick your neck out and actually risk being wrong, let alone to affirm an abstract ideal. (And the great thing about the Avon/Blake dynamic is that Blake is every bit Avon's match: he's just as intelligent and just as good at turning an argument his way... or 'manipulation', as the Avon-fans put it.)

Blake is prepared to lead; Avon isn't prepared to do anything more than stand aside and snipe at the idea of anyone leading. He represents a postmodern sensibility that distrusts faith, saviours and crusades in principle, and nowadays that plays very well to the gallery.