Harry Potter, J.K. Rowling
Dominant Si: Snape absolutely cannot let go of the past. He carries a bitterness of long lost childhood love and this bitterness spills through into the way he treats everyone. He has a particular disliking for Harry purely because Harry stirs up painful memories from his past. He relies on experience to deal with all problems and devises specific methods for everything. Snape is a stickler for rules and punishes students strictly for disobeying them. He often makes accusations against people wrongly, relying on past notions of them rather than the evidence he sees before him. He holds grudges for a veeery long time, and doesn’t always see an accurate picture of what people are like.
Auxiliary Te: Snape has a method for everything –especially potions. In his youthful textbook, he scrawls down the most efficient method for everything, but doesn’t necessarily share those methods with others. He has a systematic approach to teaching and tends to be a bit unfeeling toward his students. He gets annoyed with students who aren’t efficient in their work and is reluctant to take on anyone who isn’t the brightest and best. Snape doesn’t rely on his emotions to make decisions and doesn’t have patience for other people that do.
Tertiary Fi: When it comes to Snape’s past emotions, he often looses control of his logic. His emotions come out only in Te mean-ness. Anything that reminds him of painful experiences from the past gets treated with cold harshness (Harry reminds him of James, so he’s mean to her; Hermione reminds him of Lily, so he’s mean to her; Lupin is someone from his past, so he’s cold towards him etc). His personal feelings are much more important to him than anyone else’s, and this comes out directly in his Te actions. When the Potters are under Voldemort’s threat, he only wants to save Lily because she’s the only one he has an emotional connection to.
Inferior Ne: Snape is creative in his approach to problem-solving. He devises new methods for doing things and keeps the big picture in enough perspective to be willing to work agreeably (sort of) with people he dislikes. He makes potions to help Lupin and works with Voldemort and the death eaters even though his loyalty lies with Dumledore. At the same time, he’s not particularly intuitive about people’s true motives and is often surprised to be informed about them.
Once again, people stereotype Snape as an INTJ. However, Snape is a serious Si user –I don’t know very many INTJs that would hold on to the past for as long as Snape does. I’d say SiFi loop.