Filch watched the boy run away, and then looked at the floor again.
"Filthy urchin," he grumbled out loud. "Must be up to something."
Luckily, he didn't notice Harry had taken the brush with him.
It would not do to lose the specially enchanted thing to the unappreciative, grumpy bugger, not after it had cost Harry some favours and a few coins to get a couple of talented sixth years to design and make it.
They were having a bit of trouble working out why the gloves Harry originally commissioned for a similar purpose had dissolved after one cauldron-scrubbing detention. The flesh coloured gloves had a lot of charms on them, mainly to hide them from Snape, but nothing should have made them fall apart like they did after a single use.
Their best guess was some sort of penetrating acid or poison in the cauldrons, but not even Harry believed Greasy hated him enough to try and kill him, well not yet anyway - or at least not during a detention the slimy git personally supervised - so it had to be something else. Charming the brush was an alternative that seemed to be working out well enough though.
They still hadn't completely mastered the sleep-walking curse yet either, at least not to the point where they could add a timed alarm and a proximity sensor. That and the need to cast it every time were the current major drawbacks of his plan.
Harry was hoping they would be able to implant the curse into something like a necklace, meaning it would not have to be cast each time, but would just need to be put on and activated somehow for a set period.
Once they had, the brush and the curse together would be perfect for many of the boring cleaning chores Giggles and Greasy loved to heap on the first years, and him especially.
There was something inherently satisfying thinking about being able to get a few hours extra sleep while Greasy thought he was been punished – almost as satisfying as watching the git's blood pressure slowly rise whenever he tried to get a rise out of Harry using lame insults, but only gave Harry more opportunities to demonstrate his apathy to the twit's antagonism. Harry's record for inspiring a time-wasting rant from the nut case was currently fifteen minutes, but he was certain he was on track to get that up to at least thirty without lifting a finger – literally.