This scene was originally meant to be one chapter but when I realised it was over a thousand words I decided to split it into two, possibly three, depending on how far I get with this. It's been a little tricky to write - I hope I've got Harry and Ron more or less in character and I'm not being too harsh on them. And as always, my characters' opinions are not my own.

"I've been doing a bit of research," said Leo to Marisa on Christmas Day, "and if Potter and co. started brewing in November the Polyjuice should be ready today. Keep on your guard."

Marisa nodded.

That evening, Leo was leaving the Christmas tea, almost too full to move. He had been observing all of the Slytherins, trying to see if anyone was acting suspiciously, and hadn't found any, but now it was reaching the point where it would get suspicious if he stayed any longer. Only Vincent and Gregory remained at the table.

He spotted a couple of chocolate cakes sitting on the banisters and immediately thought that this was very worrying. After looking thoroughly but subtly around and finding nothing more, he walked around the next bend in the corridor and then stopped, waiting to see what would happen.

About five or six minutes later, Vincent and Gregory stepped into the corridor and immediately began to stuff themselves with cakes – and then keeled over, as whatever potion had been concealed inside took effect.

Leo counted to ten and then walked back into the corridor, just in time to see Potter and Weasley bending over the unconscious idiots.

"Hello," he said casually, one hand inside his pocket reaching for his wand just in case.

They looked up quickly, took one look at his Slytherin-crested robes, and glanced at each other in horror.

"Hi – uh – we were just – um – " Potter stammered vaguely, guilt written all over his face.

Leo tried to prevent himself from mentally correcting their pathetic attempts at covering up what they were doing. "Putting them to sleep so you can steal their hair for the Polyjuice Potion so you can find out if Draco Malfoy is Slytherin's heir?"

He fought to prevent himself from laughing at the shocked looks on their faces. Perhaps it hadn't been the ideal thing to say, but it was definitely worth it.

Potter evidently decided that there was no point in denying it any more, because he said "Um… yeah. How on earth did you guess?"

"I prefer not to disclose my sources," he said, smiling mysteriously. This was even easier than messing with Draco, and he couldn't help enjoying it very much.

An awkward silence fell between them: Leo was waiting for them to make the next move and they were waiting for him to do the same.

Leo heard footsteps and a second later Marisa strolled into the scene, bag over her shoulder, and leaned casually against the wall.

"Oh, hey, Leo," she said calmly. "What's going on?" She already knew the answer, of course, but it wouldn't do to give too much away.

"They're trying to impersonate Crabbe and Goyle, but I caught them in the act," replied Leo.

"Are you going to tell the teachers?" she asked.

Leo hesitated, pretending to consider the merits of each option when in fact he'd already done so, several times. "I haven't decided yet. I'd prefer to see what there is in not telling for me before I decide."

Weasley finally broke his horrified silence by yelling "Are you blackmailing us?"

"Keep your voice down," replied Leo. "You'll attract a teacher, and you have a lot more to lose than I do."

Marisa, unlike Leo, wasn't even trying to hide her glee at this situation.

"And… yes, I suppose I am, but that doesn't change the fact that unless you want to be prosecuted for illegal use of two regulated potions, you don't really have many options."

They stood there for a moment, each of the four considering what to say next.