Well, I didn't see that coming. The entire Zombie Apocalypse was orchestrated to give Renard's brother the opportunity to steal and control the newly zombified Nick. Smooth.
On the plus side, Renard has lost his Grimm but he has all the members of the Nick Admiration Society to help him.
And PLEASE for heaven's sake, let Nick's mom come back to the show and kick some booty getting her boy back. It would be a very different and possibly humor laden storyline for all those folks to work with a more typical snarly Grimm than they have experienced with smooshy loveable Nick.