Thus, I believe that
the MITD is a literal manifestation of the concept “You can be whatever you want if you put your mind to it,” and that the Protean is the creature that fits this theme. (Other people have expressed this idea in other posts better than I am here, but searching in threads seems to be somewhat broken right now on the forums, so I couldn’t find those posts.) This also explains why
O-Chul doesn’t think the MITD would believe his theory on what he is (if he is correct); for someone who has been as passive as MITD has his whole life, learning he is not just capable of setting his own course, but in fact a creature of great and immense power, capable of virtually anything, would indeed come as a shock.