No, said Aziraphale, it's ineffable.

The Dawn Locust: The first born dragon. Haloed in growth and collapse. Lord of fetus and tumor, crop and swarm. Born in the fires of the newborn universe and maintains a link to its source. Capable of extracting obscene amounts of energy from said link, but is too unfocused to defeat the Carbon Serpent. Its human form is that of a young child with missing teeth, and eyes so bright they are painful to look at. Is only interested in humanity for as long as they entertain it, but is bored easily.

The Carbon Serpent: Second born Dragon. Wreathed in cyclic horror. Mother of diamond, charcoal, and flesh. Born second but the first to think, and seeded the universe with Neumann machines, building thousands of brains the size of Jupiter. Currently locked in a war with the Dawn Locust. Her manifestation on earth is that of a middle aged woman with pupils that reflect no light. She only cares about the fate of the earth as long as it serves her purposes, and even then she cares very little. She has other planets to toy with.

The Red Worm: Third born dragon. Crowned in bloody teeth. Eater of dead gods and universes alike. Sole habitant of the frozen desolate directions beyond our sight. Only capable of entering our universe though black holes and the machinations of foolish scientists. Every intrusion upon our world is marked by bitter cold and grinding teeth. Normally dull and witless, it currently has parasitized a physicist and responds to some thought. The physicist is sympathetic to humanity, mostly. He’s been having a bad few years and sometimes the idea of eating the sun is tempting.

meltingpenguins asked:

If I may ask a follow-up to the animal/human forms of demons: Is it definitely the animals that are demons (as some demon don't have any animals) or is it more leaning towards 'it's both and fluid'? Asking because there's already some self-proclaimed 'real fans' going round making other people's lives miserable because 'you are not writing this right, gaiman said this is canon, so you're not a real fan!' Please help.

neil-gaiman answered:

I said “The other way of asking it of course, is why do the demons have people-shaped things beneath them to get them from place to place?” That’s posing a question, it’s not saying it’s canon.

And to repeat, book canon is the book. TV canon is what’s shown on TV. Everything else is up to all of you.