Color me curious. To verify: If we can justify them, we can have them? Characters yes, but what of organizations? For example, the Black Order as a whole as opposed to just Allen Cross from the D Gray Man-verse.

This also brings to mind power scaling, and how much I can have and not feel guilty of god-modding.
The Powerpuff Girls certainly suggest superhero-class personal power, but what of historical influence? How far can we take a character or group's pre-existing influence on the world prior to the initial plot? The PPG don't have much baggage, and can comfortably work within their little cast of characters to keep personal plots rolling that don't necessarily get in the way of big plots.

Consider the Brotherhood of Nod from Command&Conquer; a massive paramilitary religious organization centered around the alien mineral Tiberium and their seemingly-immortal prophet, Kane. The Brotherhood is a global-scale threat, not to mention the terraforming function Tiberium serves for both the biosphere and global economy.

Also, what of cultural influence? Like, say, Shadowrunners and the cyberpunkish dystopia their existence implies? Would they be part of the fabric of the world, or but perhaps a single city or nation infamous for corruption both economic and spiritual wherein Runners ply their trades?