User blog comment:ElfieGirl/Creature Question!/@comment-4845172-20120225193122

This is a very excellent point of observation. Again, as with other points of inquiries, the fans are being made to speculate on the whys and how-comes of the series' mythos. Unlike with other series that deal with other fantasy creatures that have pretty much been widely explained like the witches, vampires and werewolves, the mythos that Grimm surrounds itself in is an original creation (as far as I am concerned) and this originality has so much potential and elbow room for the writers, but this also comes with a certain difficulty as there are issues, such as the one you pointed out, that are not readily available elsewhere other than from the series itself. The producers should start giving us a better history and foundation of the mythology (as they well should have done so in the earlier episodes), and start moving from the monster of the week format and let some wider story arc (like that of Capt Renard) start unfolding. It's high time some major revelations happen, it's the twelfth episode already.