The Inventor, The Trickster, The Debater
Sometimes when you look at a really cool villain too close, they’re kinda sad. Syndrome’s lots of fun and has great comic moments and memorable quotes, but dang it if he isn’t an emotionally damaged dude. I spent the most space on his profile examining his unhealthy tertiary function—his Extraverted Feeling—from which most of his villainy spawns. That, and a death scene that prompted Pixar’s first PG rating, add a touch of tragedy to this otherwise upbeat, carefree bad guy.
Dominant Function: (Ne), Extraverted Intuition, “Conceptualize the Experience”
Little Buddy Pine is just bursting with great ideas. He’s got a million gadgets, and big dreams for being a superhero sidekick. He’s excited to show off his inventions to his hero Mr. Incredible, and rattles on at a mile-a-minute.
As a grown-up, Syndrome still has big ideas, and still loves talking about them. With very little prodding from Mr. Incredible, he gets caught up “monologuing” about his awesome plans. He geeks out over his robots, even when they’re creating carnage, because they’re just so cool.
Syndrome even gets a kick out of the creative ways Mr. Incredible beats his robots and probes. Sure, they’re enemies now, but genius is genius.
Auxiliary Function: (Ti), Introverted Thinking, “Analyze the Experience”
Syndrome’s not a super, so he creates his own makeshift superpowers. “Can you fly?” he asks Mr. Incredible. “I can!” He’s solved the problem of not being super by making himself super through technology.
Tertiary Function: (Fe), Extraverted Feeling, “Relate to the Experience”
Buddy worships his hero Mr. Incredible, and wants to be part of his adventures. His whole world crumbles when he’s rejected, and he goes into a bitter emotional spiral. He wants to hurt the heroes who hurt him, first by eliminating them one-by-one, and then by gloating over his nemesis when he’s beaten down.
Mr. Incredible apologizes to him when he realizes what he’s done, but by then, Syndrome rejects him right back. “I’ve outgrown you,” he says. He really hasn’t, but he needs to believe he has in order to ignore his hurt feelings.
Syndrome’s counting on being able to emotionally manipulate the people of the world into believing that he’s a hero. He wants to bask in the adulation he was denied as a kid. When his big evil scheme doesn’t work, he resorts to one last emotional attack—threatening the Incredibles’ baby boy.
At the same time, Syndrome truly believes he’s performing a service to society by offering his inventions to everyone. Well, selling them to everyone, but still, he wants everybody to have the chance to be super. What’s wrong with that, really? If he weren’t so damaged in the way he went about it, Syndrome could actually do a lot of good with his inventions.
As it is, he shows a callous disregard for human life by killing superheroes, endangering the population of the city, and gambling with his assistant’s life—which comes back to bite him when she changes sides to help the Incredibles.
Inferior Function: (Si) Introverted Sensing, “Relive the Experience”
Aside from his tone-deaf emotional intelligence, Syndrome’s big weakness is his lack of attention to detail. Sure, he’s got big schemes and an invention for every occasion, but he also has a tendency to get distracted by monologuing and accidentally throw things around with his zero-point energy gloves. He certainly underestimates his control over his robot and the ingenuity of the Incredibles to escape his clutches.
And it goes without saying that he should have had second thoughts about that cape.
Heroes & Villains of MBTI 
Interesting analysis. I think the fact that Buddy was so hurt by his hero’s rejection as a child indicates that Fi is his auxiliary, as his tertiary would not be developing yet at that age. I have him typed as an ENFP, which also gives him an ambitious tertiary function, with an auxiliary goal of forcing everyone to sympathize with him and his identity as a non-super.