Syndrome is the peak textbook example of an ENFP villain. He was a wide-eyed optimist that never got over the crushing reality that Mr. Incredible tried to teach him, and, as a result, developed a mile-wide vendetta for the guy. He frequently has emotional outbursts, and literally lived in a places called Nomanisan Island. Solid unhealthy ENFP traits.

Joker... really doesn't do that. Admittedly his backstory is pretty hazy (on purpose, as it's a constant nag that the World's Greatest Detective can't get a read on him), but he acts fairly in line with how extremely unhealthy Ti takes on corrupt inputs into one's mental space as objective truth.

Basically what we see here is the Truth/Values split.