Jag letade efter det också under en mycket lång tid, och jag hittade den (av misstag). Det heter " Fall of the Fall " (vuxen fanfiction webbplats).
Jag läste de första kapitlen utan att inse att det var det jag letade efter. Det tar några kapitel att komma till Hogwarts-delen och den nya läraren.
Kapitel 3
As to the other alternative, I have found that Mr Flourish of Flourish and Blotts bookshop is renting a small flat above his shop in Diagon Alley. I have been in correspondence with him and he seems to be quite taken with the idea of your living there. I assume he remembers you as a child. He has also mentioned that he would be happy for you to work for him on weekends to pay for your room and board.
Kapitel 7
She deserved her pain. She deserved to be screamed at, abused, and hated. She deserved punishment.
Hermione noticed through the haze of her tears, that she was holding her wand. She lifted her arm and drew it along the back of the opposite hand. “Diffindo.”
The skin split along the line she had drawn. Blood pooled in the wound and began to seep out. In the back of her mind, she vaguely registered that it wasn’t a deep enough cut to do any real damage before dropping her hand back onto her stomach indifferently.
She cried, briefly, from the pain of it while a little voice in her ear said, “Not enough.”
No, it wasn’t. She’d endured cuts and bruises before, she was used to it. She needed to feel the kind of pain Ron would feel if she told him what she’d done. That’s what she deserved. And there was only one spell she knew of that could do that. She picked up her wand again and pressed its tip to her temple.
“Crucio.”
She waited. Nothing happened. This seemed worse than the alternative.
She tried again, this time trying to push all of her anger and pain into the word.
“Crucio!”