Due to the passage of time, I have forgotten the title of the book. It may be something along the lines of 'The Dragons of-' There are dragons, living in secret. Humans have some knowledge that they're still around. Anyway, this one dragon brings a human baby back, and after some years, returns him to the human world.
There's also something about the moon not being too fond of dragons, white dragons that live on the moon, and some rather nasty ones that live on the dark side.
Cover was of night sky, with a green dragon fighting a white one.