Board Thread:Speculation House/@comment-26014103-20160521135038/@comment-3146930-20160522213106

Odds are she is the mother of all Grimm or something along those lines. From what we know of the Grimm, they become stronger and more intelligent the longer they live. This can possibly be supported by her being the one that narrates the opening credits, suggesting she may have been around for thousands or tens of thousands of years. That otherworldly dimension they are in may be the realm that Grimm are created in.