I am, very very slowly, putting together a general plot for an old-fashioned epic fantasy series.
The antagonist is an evil god, whose body was destroyed long ago. His essence survives, in extremely diluted form, in an orc-like species that are basically humans with all the good parts removed. Their chieftain starts a war against the world of mankind, but as more of the not-orcs are slain and more bloodshed is done in the god's name, towards the end of the series he takes on physical form again the lead the final march on the setting's dominant superpower.
All fairly standard fantasy stuff. But I wonder if I'm somewhat obligated to make some sort of statement on the nature of evil. While the god has his army of degenerate monsters, as the war turns his way various human tribes and nobles join him just for the sake of being on the winning side. And one of the main heroes is a human descended from angels, who has a somewhat autistically simple view of right and wrong. Not in a Mary Sue-ish, "beloved by everyone" kind of way, but more in a "constantly frustrated with human shortcomings and at odds with more pragmatic characters" way.
So on one side I have pure good to a somewhat impractical degree, and on the other I have... what?
The idea is that the god embodies mankind's worst impulses, and considers himself the true god of mankind, made up of its true essence, which is why he can never be truly destroyed. The semi-angel is all about mercy, love, unflinching honesty, empathy for even the worst people, and has no tolerance for short-term evils in the name of supposed long-term benefit. That, in my mind, makes up a theoretical pure good.
Much of human evil, it seems to me, springs from fear and ignorance, and those two are closely related. It's people's ignorance of others, wilful or otherwise, that makes it easy to dehumanise them and/or assume the worst. And fear can easily override someone's better angels. With that in mind I suppose I can have the god be all about preying on people's fears and stoking prejudices. Even among his monsters there can only be any kind of major long-term cooperation when a single strong leader can drag everyone along, while his lieutenants are all sharpening their knives.
Basically, the god is out to bring about an anarchic hell on Earth, with small enclaves in constant conflict with one another. An evil that is ultimately just self-destructive and useless. But I'm not sure how to have that as a theme, or be embodied by a character.
Does anyone have any suggestions?