Some of the mentors are obvious from the moment we encounter them, in part because of the direct impact they have on the hero.
|Obi Wan Kenobi|
Some of them reveal themselves as the story continues in the way that they make the heroes change the way they think about themselves, the people around them, the potential for their lives. Their teaching methods are not always traditional and students often are annoyed or frustrated by the mentor before they start to realize they can learn something from them.
Mentors don't always have the happily ever after, and because of this, sometimes we love them even more. Generally, a mentor knows theirs is a thankless job in the direct sense of the student offering love and gratitude. The mentor most often considers seeing the change in the hero the reward they were hoping for.
Do you have a favorite mentor in literature, TV or film? Do you have a character in your WIP who is serving a mentor position? Do you prefer a mentor who directly helps or just subtly guides the hero in the right direction?