I was talking to my sister, who was trying to write a book, and she mentioned venom in dragons. I questioned why a species would feel the need to develop venom after exerting so much energy into size, and this led to a talk about the economics of such a large carnivore existing at all.
What kind of ecosystem would need to be in place to supply these creatures with the food they need? They either eat a lot, or are very lazy (which means no wings, because that's a black hole for resources)
I realized I'd never seen a story with dragon's that properly reflected the ecological consequences of such a thing.