Laura Kristan Wilhelm, Self-employed at LauraWil Intercultural (2009-present)
I think INTJs can be a little intimidating as teenagers since they tend to do very well in school and not care much about clothes, parties, or popularity the way most teens do. They are usually well behaved and mature but are not easy for authority figures to control with either positive or negative reinforcement. And if INTJ teens think something is wrong, they will risk quite a lot to bring it to light. This sort of whistleblowing might bring them into the limelight and get them a student council spot, but normally they prefer to keep to themselves or hang with other INTJs from their accelerated classes.
INTJ teens usually have very serious outside interests like music. They may be performing at concerts and working with a language tutor to learn German lieder while their peers are pouring beer all over each other at pool parties. Probably they want to go to a top-tier university or music school like Harvard or Juilliard.
Physically INTJ teens may be a little neglectful of their appearance and prefer to dress in their own duds rather than a school uniform. They may have to be forced out of hiding behind a book or computer so they can get some fresh air, exercise, and proper food. But they can usually be reasoned with much better than most people their age.
INTJ teens might be quite sheltered if their parents allow their introverted tendencies free reign. They may have read and heard quite a lot about sex, but are smart enough to understand the consequences and are usually cautious about dating. They may wait until college or even later to start forming romantic attachments and may prefer their teachers and professors to people their own age.
INTJ teens are often epic babysitters who have more availability than more gregarious peers. Children start calming down around them and wanting to do things with them immediately. INTJs don’t court children the way extroverts would, but their quietness often makes little people very curious. They usually have cool books, comics, and toys that the kids like better than the usual ones.