CLARA CLAYTON, SEVEN

She has less of a role than some of the other repeat characters, but Clara makes an impact. We know Doc well; any woman he would love needs to impress us.

In order to match with Doc, she has to be a science nerd, and she is. It goes beyond a love of Jules Verne, though. Her telescope has an entire backstory, and she has a lifelong relationship with science. Well done.

She’s obviously brave. A lone woman schoolteacher sets off into the Wild West, arriving by train in a town where she knows no one. It’s easy to forget how risky such a move would be back then.

A practical woman who dares to adventure? Seven. It’s her clinical reactions that define her Enneagram. Doc breaks her heart, she’s leaving. New information tells her Doc loves her, she’s returning. Doc has a model train set with a piece labeled “time machine”, she believes him. Doc’s off to travel through time, she follows. She just does the next thing in front of her, no matter how unrealistic and ludicrous. That willingness is very Seven.

BIFF TANNEN, NULL

He’s our villain, or some version of his ancestral line is, throughout the trilogy. It’s only Old Biff in the second movie, the time traveler, who has any brains. Every other version of him is mean or subservient. Does he even have an Enneagram, or is he just a generic antagonist?

Actually, I think that’s our answer. Old Biff has a motivation: I want to change my destiny. He’s the only one who isn’t a cartoon. He has a fatherly patience with his younger self. Obviously he’s pretty smart. In just a few seconds he understands all the ramifications of time travel, as well as the motivations of Marty and Doc. That’s why he warns himself to look out for them in the future. A little too convenient? Do we believe that bully Biff can really become this wiser Biff? But then he leaves the almanac bag and his broken cane handle behind in the car, so how clever is he?

Nope, he’s still just a plot device. No Enneagram.

MARTY McFLY, ONE

He’s not a rule-follower or particularly organized. We know this by the amount of school tardy slips he’s racked up. He’s not chivalrous; he leaves his unconscious beloved unattended on a porch swing in a dicey neighborhood. He’s a loyal friend and well-liked by strangers. He’s fairly athletic, riding multiple iterations of a skateboard with ease. If it weren’t for the tardy thing I’d call him a One. He has a certain can-do attitude and a love of adventure that might indicate a Seven. His ability to charm the past and come out a winner, and his hatred of being unfairly labeled a “chicken”, suggests a Three. So, what have we got?

He’s not interested in how Doc invents things. He doesn’t chime in or brainstorm, or even try to understand. Not a Seven.

Besides being a time traveler, Marty really has no vocational plan. What did he like to do before Doc intervened? Drive a 4×4 is about it. Not a Three.

He’s a man who needs a mission, and when it’s given to him — save the past to save the future — he’s engaged and active. The tardies are a sign he’s drifting, looking for that motivating moment to come from outside himself and change his life. One.

DOC BROWN, TWO

The very first opening moments of the trilogy tell us Doc Brown’s Enneagram number. Look at all those clocks! He’s not just repairing or tinkering or inventing, he’s collecting. The filmmakers may have been winking at us about the theme of time in BttF, but they’ve also given us key information about Doc’s character. As a Caractacus Potts type, Doc could be a Seven or an Eight, but this collection indicates he’s a Two. 

When he goes into the future, what does he do? He looks up people he cares about — Marty — to see how they’re doing. When Future Marty is a mess, Doc ropes Current Marty into a time travel event in order to help him. Very Heart Type.

It’s possible this is what makes his love for Clara in the third movie so sweet. He’s been solely focused on science, and as a collector he’s had much to satisfy him. His friendship with Marty is dear to him and has sustained him. The way his heart opens to Clara, though, against his will even, is charming. How else do you make someone not classically handsome the hero of a love story? The filmmakers and Lloyd tapped into something hidden but essential in Doc. This twist — the last film is a romance! — works so well because he’s a Heart Type.