"Was it really different?" Fred and George shouted in unison. "How exactly did you notice? What were you thinking about that made the Scouring Charm different?"
"I can't really say..." Mr. Filch frowned and thought carefully. "I was just watching those House-elves clean... and every time, I felt like... shouldn't the Scouring Charm have a few bubbles too?"
"When professors punished students with detention, I saw those students use the Scouring Charm. Their Scouring Charms... I remember they made bubbles too..."
"That's right! Those bubbles would even stick to the armor, and every time their detention was over, I'd have to go clean it all over again. Annoying as hell!"
"Wait!" He seemed to think of something and immediately widened his eyes at Fred and George, questioning them in a vicious tone. "Was this your rotten idea? Is that why the Scouring Charm turned into this?"
"Ow!" Fred raised both hands with a grin, striking a pose of surrender. "You react pretty fast. Your first thought was that we were up to something..."
"Mr. Filch here..." George raised a hand and pointed at Vizet. "Seems to trust Mr. Lovegood very much! Even though the 'Fake Wand' was designed by Mr. Lovegood..."
"That's not the same!" Mr. Filch said without the slightest scruple. "Don't think I don't know... exactly how many bad things you've done!"
Fred shrugged. "We've never even blown up a toilet. How many bad things could we have done?"
"How about..." George raised an eyebrow at Mr. Filch. "Next time we blow up a toilet, we'll let you know so you can come and observe? That way, you'll know exactly how many bad things we've done!"
Vizet said, "The final effect of the Scouring Charm is just like its incantation, 'Scourgify'—it can make an object clean. But in