"So what are you going to do?" asked Potter.

"Well, maybe our objectives aren't as different as you might think. I do also want to find out who Slytherin's heir is."

"And I'm Muggle-born," Marisa admitted. "So I'm in danger, too. At least, I think I am."

But their attempts to negotiate weren't working: Weasley had the look of someone who had figured something out.

"You're Asriel," he said, making the name sound like a deadly insult.

"I am."

"You're the son of You-Know-Who's most infamous supporters."

"I am."

"You're the Heir of Slytherin!"

Leo blinked at the unexpected accusation. "That is a completely unfounded accusation. You are jumping to conclusions."

"You haven't denied it!"

Leo rolled his eyes. "I am not the Heir of Slytherin."

"He isn't," agreed Marisa. "Although I can't be absolutely certain of that."

Leo shot Marisa a look. This probably wasn't the best time to bring that up again.

"You're lying!"

"Is there anything I can say that will convince you that I'm not the Heir of Slytherin? An account of my movements during the attacks? Haven't you just seen that I'm friends with a Muggle-born?"

Leo didn't like the way this conversation was going. Suddenly he'd been flung onto the defensive, and he wasn't taking kindly to that.

Weasley had drawn his wand. Leo drew his own.

"Do you really want to do this?" he asked. "I can probably out-duel you with one arm tied behind my back and my eyes shut. And bear in mind that you'd be wise not to act unkindly towards me, considering that I can still inform the authorities about what you've been up to."

There was another moment's silence. Leo stared at Weasley, ready to throw up a shield at a millisecond's notice should it be required.

Eventually, Weasley slowly lowered his wand, but he didn't tuck it away. "I still think you're Slytherin's heir," he said defiantly.

Leo rolled his eyes and mouthed to Marisa: "Gryffindors!"

She nodded.

"And what are you going to do about it," asked Leo. "Without any solid evidence – which doesn't exist – you'll never get a grown-up to listen to you. And there's no way your Polyjuice trick will work on me. Where's Granger, by the way? I thought she was in on this too."

It was the wrong thing to say. "What have you done to her?" screamed Potter (quietly; at least some of his words had made an impression).

"Absolutely nothing," said Leo, perfectly calmly.

"What are you going to do to her?"

"Absolutely nothing. Well, if you keep going at this rate, I'll turn her in for illegal potion-brewing, but nothing else. And generally, when someone's trying to blackmail you, it's a good idea to at least listen to their demands."

"Well?" snapped Potter. "What are they?"

Leo paused. To be honest, he didn't really know exactly what he wanted. "To begin with, you can tell me everything you know about the Chamber of Secrets."

"We don't know anything," said Weasley.

"Liar," replied Leo, who knew at least some of what they knew, thanks to Marisa's information.

"Why would we tell you? You already know everything, don't you?"

Leo was getting very annoyed by this point. He was half tempted to just forget all this and turn them in. "No, I don't. And if I did, there would be no point in asking what you knew."

"Yes, there would," said Weasley. "If you knew what we knew you could work out whether we were a threat and you needed to – to kill us."

"Congratulations!" said Leo, "that's the first halfway intelligent thing you've actually said today!" The sarcasm was probably a bad idea, but his patience was running out by now. "But I'm still not the Heir of Slytherin. Now are you going to tell me, or not?"

Potter and Weasley glanced at each other, weighing up the risks of telling him against the risks of not telling him, before Potter said "Yes" at the same time as Weasley said "No."

Leo blinked and waited to see if the two Gryffindors could reach an agreement.