OK, quickly, thanks to this forum. I really appreciate the space. I've never even done a forum before because I haven't found a topic or crowd that was deep enough. Not like I'm so deep! So thanks for your patience.

I just want to put out a theory for your consideration. I'm going to work on it a bit more with your (hopeful) feedback...

Cooper is now a lodge entity. He has been for a long time. But he is so attached to the LP story that he is stuck in a time loop of his own devising, in which he is attempting to leave the lodge and become an FBI agent again. 

The Mr. C that has been wreaking havoc is unfortunately the physical form of Cooper, possessed by BOB. This is why when Laura Past sees him in the woods she screams. I think. That part was super upsetting for me because it is the true nightmare of the doppelganger--that you are not who you think you are. Also time loops get messy...

In a related note, I LOVED the blending of time that Lynch achieved in the finale. It was impressive and calls back to the Mantra about future pasts, etc.