Board Thread:Speculation House/@comment-71.17.68.254-20130907025506/@comment-3146930-20140729195319

I have a theory that the reason they attack humans/Faunus/living things is because they gain a stronger boost of power from the soul, so if they hunt in larger packs there is a better chance of success. Also Grimm are very animalistic so far, so they themselves may not know that killing another Grimm will cause them to gain more power.