I know basics of MBTI- I know what each letter in the type means, I know my type, etc, but I don't use it to create a character. My characters are constructed mostly with their flaws plus some other personality traits sprinkled on top haha cx
However, my friend is really into MBTI. She also ships my two characters, Kestrel and Jerzy, and she told me that for her those characters looks like those two types, and those types are perfect for each other.
I had doubts, as my characters hide a lot of their feelings, especially Kestrel, she's a liar and she also lies to herself a lot, and it'd be hard to see her true self just from what was shown in the story so far. And the description sounded kinda off (maybe because it focused on good traits while I mostly see bad traits in my OCs). So I decided to take the test for them (...and also when I started doing it, my friend asked me to do it for other some characters as well, as she wanted to make sure if she's right).
And turns out, she got every single one of them right : O
I don't know how you MBTI people do it, it's like magic but it somehow works
Soo turns even that even if you don't use MBTI to write your characters, they still have their type which can be recognized by people who are into MBTI 