User blog comment:Maki Kuronami/Extra Lesson: Attack on Grimm/@comment-25091485-20141017103658

I wonder how big is the negativity radar of the Grimm, I mean there's just beowolves at first but then the panic of a small village attracted a Nevermore of all things. So if the whole city of Vale is in chaos, would there be enough negativity to pull Grimm from, lets say, the Dragon island nearby?

So they say that there are a ton of new breeds of Grimm being discovered, does that mean that Grimm evolve into another form? (Beowolf -> Goliath) That seems really unlikely, since they probably just grow in size, strength and bone plating.

So that leaves the question, how are Grimm made? Do they spawn from some central location which determines what type of new optimised Grimm to spawn? Can Grimm create themselves (the older ones presumably being the creators) ? And why not just create a ton of Goliaths, Deathstalkers, Nevermores and flatten everyone?

The attraction to negativity and the general motive to screw with humanity leads me to think that Grimm may be the product of human's negativity or perhaps a manifestation of dead aura/souls? Given RWBY's emphasis on aura and (simple) souls, I think this seems plausible.

On a side note, PREPARE FOR THE HUMANOID GRIMM / RIDICULOUS / BADASS LOOKING GRIMM