Not that sort of demon

In Philip Pullman's His Dark Materials trilogy, a daemon is a physical manifestation of your soul appearing as an animal. It is typically of the opposite gender to you, it is your constant companion and, when you're a child, it can appear in almost any form. As you get older, it settles down into a creature that reflects your adult personality. It is the single most brilliant idea in fantasy literature since Frodo decided the only way to treat tacky Second Age bling is chuck it into a volcano.

I don't want to boast or anything, but yours truly's daemon is ...