Next in my old favorites list is Harry Potter fanfic "The Squib and The Death Eaters" by Ozma, posted February 11th--February 18th, 2002. A group of Death Eaters, including Snape as a spy for the Order of the Phoenix, victimize Filch during Harry's fifth year.
The fanfic takes thoroughly disliked minor character Filch and manages to turn him into an interesting and sympathetic protagonist who is too often hurt by a prejudiced wizarding world. The parallel between squibs and people born with disabilities is made much more overt. Filch describes being abused in attempts to awaken his magic--the way Neville's magic first showed itself to save him from accidental defenestration--as something similar to the real world practice of abusing children with disabilities out of a belief that these children are fake and their real children have been spirited away by fairies and this will make the fairies give back the real children. Even if the parents mean well in a manner of speaking, they end up committing abuse out of prejudice. It is a believable crime in the wizarding world. This abuse is part of the overall bad treatment Filch encounters through his whole life.
Though the mischief managed by characters such as Fred and George Weasley is generally looked upon as harmless fun or even an act of independence asserted against a harmfully restrictive authority, this fanfic depicts such mischief as inherently harmful against a poor old guy who just wants some basic respect. Argus Filch was hired to take care of the school, something he does very well without magic, and yet people continuously try to make his life difficult. When you think about it, it really is unfair to the caretaker. He's just trying to do his job, after all.
Of course, Filch is flawed himself, as he responds to the pranks with unnecessary aggression. He essentially recreates the pain done to him by trying to make the offending students feel a similar pain. As Dumbledore disapproves, the readers ourselves are not to approve. While unduly nasty, Filch is made very sympathetic, so we can essentially hate the sin and love the sinner at the same time.
When the Death Eaters victimize him to harvest "squib bits" for a spell, it is one more occurrence of the trend in which Filch is disrespected because he happened to have been born a squib. This event causes Filch to think about how people treat him badly, allowing for the readers to be introduced to his side of things as well as sending the character on the path to make him reach his Flowers for Algernon moral dilemma.
The fanfic is dark and has a bittersweet ending. Filch suffers torture at the hands of the Death Eaters and then has to live with realistic PTSD. The fic is sad, really forcing you to feel this man's pain. His pain is so great that even Peeves feels conflicted about harassing him.
What can I say? It's a good fic. It makes Filch sympathetic. It actually makes me regret laughing at McGonagall calling the film!canon Filch a "blithering idiot", and that's a completely different character. The fanfic will definitely stay on my favorites list.