Grimms' Fairy Tales
Wise Old People and Talking Animals
Who better to give advice, right? Guides in fairy tales are frequently mysterious, coming and going as they please, with nary a clue to their back-story. But occasionally we get glimpses into their reasons for helping the protagonists, such as the birds from the tree that grows on Cinderella's mother's grave, which is a pretty obvious metaphor for the ghost of her dead mother helping her out. Or sometimes an animal helper turns out to be enchanted, and once the protagonist gets what they're after, the protagonist can disenchant the animal helper. Nothing wrong with a little "I'll scratch your back if you scratch mine."