Hermoine is some sort of FiTe user. I can't see her being an INFJ -- she backs down from nobody, and if there's something upsetting her, she'll make it evident. Rowling said herself that Hermoine is an exaggerated version of the author in her youth. Rowling is an INFP, so I guess that makes sense. Hermoine isn't an INFP herself though, the TE is too strong for that. It's weird calling Hermoine an ISTJ or INTJ, but I guess those fit best. Meh, she's a fictional character.