The newest micro fiction is a POV from Mister, which probably dashes some fan theories as to Misters true nature, but not potentially others.
It is clear that Mister is totally cat, whatever else he is. I would point to one visual clue in the comic though:
His Cat Bowl has Emperor on it, suggesting he is a Sith Lord (Mouses has Chewbacca on it) is Harry’s subconscious trying to tell us something (it is quite a bit smarter than Harry, after all as well as better dressed and more accomplished with the ladies) and that Mister is the scion of a Malk, Cat Sith himself, a changeling, and lord in Mab’s court. No wonder Mouse obeys him.
I would also point out, the derogative term applied by Mister to humans is one that Bob has applied to humans, I would need to check the rest of the books, but this may be a Faerie usage.
Mister is often referred to as “my bobtail tomcat” the tail was missing when Harry found him as a kitten.
of course Malk’s (And presumably their changeling scion), have very long tails, which would be a dead give away
I think that Mister the White God theory is now officially Kaput.
The reason that Mister looks like himself under the Sight is that there is nothing more terrifying or more grand than a cat, and nothing that he would rather be.
this is why he hasn’t made the chipotle to be a Malk perhaps