Board Thread:Speculation House/@comment-71.17.68.254-20130907025506/@comment-3146930-20140127112310

It could just be that larger Grimm are better hunters, which is why they are so big in the first place. I mean Ruby hit a small Nevermore when entering the forest so maybe Grimm grow over time and only the ones that have been around for a long time grow that big. This could be why some of the smaller Grimm travel in packs, as they have a better chance of competing with the larger Grimm; fighting strength with numbers.