User blog comment:Zathronas/Analysis by an author: Volume 2 episode 9: Search and Destroy/@comment-10390252-20141003134556/@comment-24218038-20141004033328

Now we're going into Babylon 5 territory. Survival of the fittest and what-not.

The Yin and Yang theory is pretty much the protagonist-antagonist relationship. To make a good arch-nemesis, you have to give him a motivation that is the complete opposite of your protagonist unless you intend to change his enemy into a friend.

In this case, The Grimm are the exact opposite to man so there can not be a middle ground where they can understand each other. The inevitable result will be all out war.