Same with Hermione. ISTJ children follow rules. She is absolutely IN LOVE with her course of studies at Hogwarts. Typical INJ behavior in those circumstances is to read everything they can, going way beyond grade level to delve into their interests. Her bent to take risks at that age--the potion that changes them into Slytherans, using the time device that lets her take multiple classes, etc. all point to INTJ over ISTJ.
I'm sure there are lots of INJs on this forum who, when they found classes/teachers/professors that honored their intellect and actually let them explore content and theory deeply, were also able to have info at their fingertips because it fascinated them and therefore they processed it in ways that allowed it to stick in their memory.
I think I agree. Glad to see I'm not the only one who finds Hermione more INTJ-ish than otherwise.
The Polyjuice potion was her idea, even though it broke "about fifty school rules." And earlier, in
Sorcerer's Stone, she encouraged Harry to break into the "restricted" section of the library.
The thing about SJs is that they tend to be joiners, even the introverts, perhaps because it's the appropriate thing to do, or perhaps because it's just so easy when there are so many fellow sensors all around you. But Hermione is not a joiner. INTJs are the same way: independent bordering on isolated. We never see Hermione in a clique with other girls (in the movies, at least), and that's very typical of INTJ girls. Whereas ISTJ girls are constantly surrounded by others similar to them, INTJ girls grow up wondering why the hell they're so different. And Hermione seems very unique and isolated indeed.
As for her doing things like impugning Luna's fantasies, well, there are a lot of very dry INTJs out there. For example, there are INTJ scientists who are strict materialists who will deprecate those who believe in ghosts, spirits and theistic religion.
Similar could be said about the "potion of living death" incident. If a friend offered to install personally written software on my imac, insisting that it would make it run faster, I'd politely decline. Even if he proved by demonstration that his own computer ran faster since he installed his own software, I'd still decline.
But if Apple offered a fix package to increase my imac's speed, I'd download it in a minute.
That's not because I'm secretly an SJ or that I have a respect for authority, it's because certain established ways of doing things that have proven reliable are preferred, as a default, over new ways of doing things. If my friend's software came out as a purchasable product, I'd be convinced it had gone through the necessary testing and was "safe" to download. So I'd consider Hermione's skepticism for Harry's innovation to be entirely justified. I might have done the same as her, particularly at that age.
Being an Intuitive doesn't mean you have to reinvent the wheel everyday, all day.
I never met an ISTJ who so totally
reveled in academia and higher education as Hermione. I suppose there might be some, but they're rather the exception. For INTJs it seems to be the rule.