Scott, do you feel, as a character, that Doc grew at all over the arc of the trilogy? Which, I guess, leads one to the question of 'does a mentor or a trickster NEED to undergo character change in the course of a story?' Obviously Brown has the most compelling change occurs in Part III when they introduce a love interest for him. Though much maligned, I actually LOVE parts II and III of this series. Two especially. It goes to some pretty dark places and has some truly clever twists on the time-travel tale. Oh and I begged my wife to postpone our wedding date by a day or two because I was invited to a press screening of Wong Kar-Wai's "In the Mood for Love." And I'll be damned, she agreed to it! Christ, what the hell is wrong with us?!?!

While in some stories, multiple characters go through a metamorphosis, it's certainly not necessary. And in most movies, the Protagonist's transformation dwarfs other characters' changes in terms of breadth or significance. So do Mentors, Attractors and Tricksters undergo character change in a movie? They can, but not necessary as their primary function - normally - is to feed the Protagonist's metamorphosis. Re Doc Brown: Over the course of the three movies, while his essential persona doesn't change, he does have a change of mind: At first, he thinks mastering time travel is a genius idea. By BTTF3, as I recall, he regrets having discovered how to do it, even wishing he hadn't. But no, I don't think he goes through anything approximating a personal metamorphosis.