I started watching a short while ago and am now at the end of season 5. In the first few seasons there was a conflict between the Royals and the Resistance, and it seemed the Royals had a masterplan. I was very curious to learn what that plan is. Now it is all about HW and Black Claw without any kind of resolution for the Royal-Plot. Or at least so it seems to me. Or have I missed something?
Pardon, if there are some mistakes in this post. I'm German :) And it is a whole lot of fun watching Grimm in English with all the German in it.
The Royals originally wanted the key that Nick had and then once Diana was born they wanted her since she had Royal blood. The Royals lost their King, a prince, and others at the end of season 4, so they probably had to regroup, or Viktor who is supposedly the new King had different plans than what the Royals were doing before.
I think it's really important to also remember what Meisner told Renard when they spoke in Renard's office way back in "Lost Boys." When he mentioned Viktor, he told Renard that he had struck a deal with the Resistance as payback because he wasn't happy with Frederick for replacing him with Kenneth. Viktor helped Meisner take back Diana in exchange for him killing the King.
My guess is that even though the Royals had to rebuild, with them having suffered such enormous losses and Viktor taking over as the man partially responsible for those losses, there's a lot of changes going on with them, and it probably involves a lot of in-fighting as usual. Whatever the Royals' plans were before, which involved bringing Diana back to Vienna, those plans have drastically changed. If what Meisner told Renard was true, and I think it was, Diana is probably the last thing on Viktor's mind.