Argus Filch had had enough of the Weasley twins. They were beyond infuriating. Absolutely repulsive. And, perhaps they were going to give away his secret.
The Weasley boys have always been in his office to get ready for one detention or another- mouthing of to Severus seems to warrant 100 lines of punishment for each one's insult. They're pranks landed them in the most back-breaking labor Argus was allowed.
Oh, how he wished he could use the old methods. First, he'd chain them to the way. Then, after a week or so, he'd stretch their limbs as far as he could. Then he'd throw them to….
Oh. Not another one. Another Filibuster's. He recognized the handwriting, addressed to him. How witty. Of course, it would probably mean there'd be a display somewhere, perchance the dungeons, meaning he'd have to clean it up. The miscreant twins seemed to enjoy making him work. What's more is he never used magic around them. Of course, he couldn't. He was a Squib.
The firework should have gone off by now. Argus cautiously went over to examine it more carefully. It was a small one.
It burnt already, he could see. But it didn't explode. It was broken. A squib.
Yes, he knew those two nuisances had finally learned his secret.