It all started with a random inflation idea by  Saphiros's shindan generator:

"Curus is enjoying the view. Curus is panting, with a stomach that is 100 ft wide."

Now, this isn't quite that big of a stomach, but what's there is a nice comfy cushion for this dragon. I might have been inflated with heavy water or even air, or just decided to fatten myself up with special belly-widening food. Whatever you think I've done, if you plan to stick around near a scenic vista, the best way to do it is while being supported by your own huge belly.

Very well done commission by  Saphiros - follow him if you like this kind of stuff.