I've been thinking a lot about plot possibilities for the 'Cats and Demons' story. Including a different title for the story altogether. I like the idea of 'Cat King' but I'm still thinking it over.
One of the ideas I had for the story was instead of the cat being crowned as the new king of Hell because the demons thought that it was a good idea, it become the new vessel for the king of Hell. I liked the idea of the actual king of Hell being so evil and toxic that it corrodes every physical body it possesses. Including its original body. So every few hundred years or so the king needs a new body to posses. So now not only does Diane need to save her cat, she needs to save her before her body become too corroded.
Another idea was Diane getting some sort of cool battle scar from when she first confronts the Hell king right after he possess her cat. It would establish the great challenge she'll have ahead of her as she continues her quest and the scar would act as a sort of reminder of the king's power over her cat.
Some thoughts like that. I'm still working things out but this is the general direction I'm heading in with this story so far.