Board Thread:Episode Discussion/@comment-410526-20160702223237/@comment-14138255-20160704195610

It could be possible (but not probable) that the Grimm are Aura based, but based off of one person's Aura (and no one can read the Grimm's aura because the Grimm aren't actually alive, perse, the person they're trying to sense isn't there). All of them are Aura manifestations coming directly from Salem, and when one dies they disappear and are partially refunded to Salem.