A/N: Although I do think Filch can be a despicable character, I also think he's rather misunderstood and if you look at his reasons for being the way he is he's actually quite sympathetic. There is something rather sad about a man whose only real friend is his cat. This is my little character study on Filch and his relationship with Mrs Norris. It may or may not be compatible with any more information we get about Filch from Pottermore, but I don't have a beta account so this is my own version of why Filch is like he is.

Disclaimer: I don't own Harry Potter.

One True Friend

They all thought him crazy. He knew they did. Even if the taunts weren't coming at his face any more and most of the mockery was done behind his back, he knew what they thought. Some of the teachers even seemed to agree with them, treating him at times with just the same kind of scorn as the students did. They viewed him as nothing but a crazy, mean-spirited, ill-tempered barmy old man.

Well, as far as he was concerned, let them think that. Nothing had changed since he'd been here. The kids were all just as vile and rowdy and loathsome as ever: different faces, but with the same nastiness and cocky attitudes that he remembered from his time. Of course, he'd only lasted a year here. It had been a struggle to even get him a place at Hogwarts first. His sister had gotten her letter, and then two years later when he'd been expecting one it never came. His parents had written to Professor Dippet, protesting that there must have been a mistake, and the headmaster at the time had conceded that it might be possible and agreed to give him a chance. However, it had quickly become apparent that his lack of magical talent wasn't just that he was a late bloomer – he genuinely had no magical ability whatsoever.

The other students had teased and mocked him for it – calling him useless, catcalling names such as muggle and squib which he knew were true, but hurt nonetheless. They'd pranked and tormented him using magic they knew he couldn't retaliate to, for no other reason than their own sadistic enjoyment. He didn't fit in here. This was a school of magic, and he clearly had no aptitude for performing spells or sorcery of any sort. That made him an outsider, and nobody wanted anything to do with him.

After a year of torment his parents had finally given up on him and bundled him off to a muggle boarding school, hoping in their embarrassment that everybody in the wizarding world would quickly forget about him. Argus hoped they would forget him too so that maybe then at least he could forget them, but the memories of the torments they'd inflicted wouldn't fade. He couldn't honestly say the muggle boarding school had been a huge improvement on Hogwarts, but at least the bullies there hadn't been able to use magic against him.

Many years later he'd ended up living in a muggle neighbourhood, working as cleaner at the local town hall. Not a very fulfilling life, but at least nobody gave him any trouble and he'd distanced himself so far from the wizarding world that he didn't have to worry about it any more. It was that little town he'd been living in when he found her.

She'd been rummaging through his rubbish bins one night, and when he'd gone out armed with a sweeping brush to find out who was raiding his trash, instead of the tramp he'd been expecting he heard a helpless little mew. Looking down, he'd seen a cat looking up at him with wide amber eyes. She didn't look mangy, but one of her forepaws was bloodied and he left ear was torn, suggesting she'd been in a fight. Argus was tempted to just give the cat a poke with his sweeping brush and tell it to "shoo!" but there was something about the way she was looking at him that made him hesitate. She was just staring up at him where he stood in the doorway with what seemed like a patient, pleading expression on her face, as if asking to be let in. Nobody had ever looked at him like that before. Everybody else just seemed to give him a look of scorn, or wariness, or contempt, but this cat was looking at him as if to say, "I know you're a nice man. Please help me out."

Part of him wondered if he was going crazy, reading emotions in the face of a cat, but he'd decided to take her in. Fed her some tuna, cleaned the cuts on her paw and ear, let her sleep on his bed. And she'd stayed with him. Even long after she'd got better the cat hadn't left his house or his side, returning his kindness with steadfast loyalty and affection. That, Argus thought, was the first display of friendship he'd ever had from anyone.

When Dumbledore had found him years later and persuaded him to take a job at Hogwarts, Mrs Norris had come with him. Argus himself had been uncertain about getting involved in the wizarding world again, but he'd recently lost his job at the town hall when it underwent a renovation and the owners contracted a new cleaning company. He knew he had almost zero chance of getting a new job in the muggle world given his poor qualifications, and taking the position of Hogwarts caretaker would give him security in his old age. He'd worried that Mrs Norris wouldn't like it and that she might run away from the castle to try and get back to their old home, but she'd stayed, seemingly content as long as she was with him. If anything, Argus thought she found just as much satisfaction in helping catch out the horrid, troublemaking students as he did.

People hadn't understood what it was like for him when she'd been petrified. The panic he'd felt when he thought she was dead, that his only friend had been taken away from him. He knew what people had been saying, laughing at him behind his back, "Jeez, it's just a cat. He needs to get over it," but they didn't understand. Mrs Norris was so much more than just a cat to him. She was his friend, his loyal companion. When other people wouldn't even give him the time of day Mrs Norris was always happy to see him – just for an affectionate stroke, or to rub against his ankles, or give him that look as if to say "You know, I'd really like some tuna right now. Pretty please?"

Now, as Argus sat here reflecting with a mug of butterbeer in one hand and Mrs Norris curled up in his lap, he reached down to give her a scratch behind the ears. Her felt her begin to purr softly and smiled to himself, glad that even if the rest of the world hated and despised him, he could always count on her to be his one true friend.