Argus Filch became something of a father figure to Harry, quelling Harry’s friend’s worries about pedophiles. He found out about the Dursleys foul treatment of Harry, and although he couldn’t do any magic on them, he did take a train to their house and spend a week sleeping on their lawn. Petunia nearly had a heart attack, and Dudley stopped going outside, as every time he did, Argus hissed at him and demanded satisfaction.
Harry had to explain to him that his Muggle relatives probably didn’t understand what he meant, and that none of them knew how to use a sword anyway.
In any case, the neighbors were disgusted at the man who lived on Number 4’s lawn and claimed to be a ‘visiting uncle’.
Since Dudley had stopped leaving the house, he’d become obsessed with playing Dungeons and Dragons online, and lost eight stone simply because he was too fanatical to remember to eat. He met a girl online that seemed to share his interests and he met up with her one day at a café, only to find that her name was Sirius Black and she (he?) was Harry’s very angry and wrathful godfather, out for revenge.
As he was beaten crudely around the head with a stick, he wondered where his life had gone wrong and why everyone seemed adamant to blame him for his parent’s faults. And why this insane person who was obviously a wizard wasn’t just using magic.
On his way home from the café, he found a flyer advertising the ‘Order of Nargle’. He became an avid member and left his family to live on the commune and learn the ways of the Snorkack.
Snape decided that it would be advantageous for him to keep Harry around, and decided to try and adopt him. He and Argus Filch began a custody battle that frankly baffled the newspapers.
After a few years, Harry came of age and it became a moot point. Strangely, that didn’t stop the battle, and after a few more years, the courts decided to simply ask Harry what he wanted.
By this point, Harry was twenty three and living in sin with Draco Malfoy and Susan Bones, who had changed her name to ‘Sunburst’. Strangely, Harry, Draco and Sunburst were of the few who had not joined the Order of Nargle. Harry told the courts that he loved both Snape and Argus equally, and couldn’t they all just get along?
After reading Harry’s quote in the paper, Hermione Granger came back from her research trip to Italy and put him in a drug rehab program. While still in England, she met up with Ron Weasley again and had a wild fling which culminated in a tattoo and several muggles needing to be Obliviated.
And they all lived adequately ever after.
The Chamber Strike, Chapter 1