This is about a friend of mine. I think she's an INTJ, but I could be very wrong. Here are some clues:

She is definitely introverted and she is almost certainly a judging type. If you are familiar with the Enneagram she is almost certainly a 1w9.

I imagine she is a T-type but I am not sure, she does sound like stereotypes of a T. Back in High School it was a running joke that she was a robot. This is because she is unemotional, extremely intelligent, hard-working, she was chief of the tech crew, dresses plainly and has very little expression in her voice. She also has a dry sense of humor.

However, she is not completely a cold fish. While logical and good at math, she is always much more focused on social issues and people. She is very pragmatic in this respect and often takes issue with university for teaching useless knowledge that can't be applied. I would peg this practicality as Te. While not a social butterfly she is friendly and fairly sociable. She also is a very good listener.

While a reasonable person, she is a bit rigid. She does tend to judge others and thinks of herself as THE authority on ethics. She often jokes she is wise and knows everything, but I am not so sure she doesn't believe her own joke. Still, she doesn't come across as arrogant most of the time, she just has a lot of confidence in her own judgment. She is vehemently opposed to drinking and drugs and has a hard time accepting some of her friends perform such acts. She has difficulty seeing things from a point of view besides her own. When she was in debate club, she said she couldn't argue against gay marriage, because she wasn't against it and it was the inferior position.

I would say her dom perceiving function is Ni, because she has all these visions about how she will change the world and is very uncompromising. Still, I could buy the opinion she's an S, since she seems so pragmatic.

If you can think of other relevant points let me know.