So I've been thinking about this and reading all the posts. Sorry for being quiet for a while.
The dragon is a major character in the book. He's extemely powerful, but also a bit off the wall . . . as are most of my characters. *grin* I've thought of what was right for the character and he's the sort of dragon who gnaws on bones, especially if it will unnerve someone.
I'm not sure about the rest of the details. At the moment, he doesn't have a lair, for reasons I won't give away. As far as the physiology of dragons go, I can get away with not defining that for reasons I won't go into because they're spoilers.
Sooooooo, In this world, dragons gnaw on bones mostly because it terrifies humans.
Thank you all so very much for the input.
It really helps to hear different viewpoints.