I have recently started a Harry Potter fan fiction, starring an original character named Kali Wintersbane. She is a trans-girl, and attends Hogwarts. She is going to end up being a somewhat morally ambiguous character. One of the things leading to this will be that, because wizarding law doesn't let her transform into a full female legally until she turns 17, and because some potential friends find out she has a penis and reject her, she will have no human friends at Hogwarts. I have already gotten to her sorting, where she is in Ravenclaw. (She rejected Slytherin due to its tendency to attract bullies.) And it is a perfect fit for her, since she's going to be smarter than even Hermione, and have a natural knack for languages.
It is a slightly AU future, which allows me to make decisions about things that don't have any information in canon, or things I think should have happened in canon and didn't. For instance, Harry is the new DADA teacher; with the death of Voldemort, the job is no longer jinxed. They've also ousted Professor Binns, for being a useless teacher. Oh, and Professor Longbottom will be the Headmaster. :-)