Harry Potter and the Methods of Rationality

Harry nodded, blowing Draco's mind completely, and said, "What if Lucius comes up with the same idea I did, that the problem is stronger wizards having fewer children? He might start a program to pay the strongest purebloods to have more children. In fact, if blood purism were right, that's just what Lucius should be doing - addressing the problem on his side, where he can make things happen right away. Right now, Draco, you're the only friend Lucius has who would try to stop him from wasting the effort, because you're the only one who knows the real truth and can predict the real results."

The thought came to Draco that Harry Potter had been raised in a place so strange that he was now effectively a magical creature rather than a wizard. Draco simply couldn't guess what Harry would say or do next.

"Why?" Draco said. Putting pain and betrayal into his voice wasn't hard at all. "Why did you do this to me? What was your plan?"

"Well," Harry said, "you're Lucius's heir, and believe it or not, Dumbledore thinks I belong to him. So we could grow up and fight their battles with each other. Or we could do something else."

Slowly, Draco's mind wrapped around this. "You want to provoke a fight to the finish between them, then seize power after they're both exhausted." Draco felt cold dread in his chest. He would have to try and stop that no matter the cost to himself -

But Harry shook his head. "Stars above, no!"

"No...?"

"You wouldn't go along with that and neither would I," said Harry. "This is our world, we don't want to break it. But imagine, say, Lucius thought the Conspiracy was your tool and you were on his side, Dumbledore thought the Conspiracy was my tool and I was on his side, Lucius thought that you'd turned me and Dumbledore believed the Conspiracy was mine, Dumbledore thought that I'd turned you and Lucius believed the Conspiracy was yours, and so they both helped us out but only in ways that the other one wouldn't notice."

Draco did not have to fake being speechless.

Father had once taken him to see a play called The Tragedy of Light, about this incredibly clever Slytherin named Light who'd set out to purify the world of evil using an ancient ring that could kill anyone whose name and face he knew, and who'd been opposed by another incredibly clever Slytherin, a villain named Lawliet, who'd worn a disguise to conceal his true face; and Draco had shouted and cheered at all the right parts, especially in the middle; and then the play had ended sadly and Draco had been hugely disappointed and Father had gently pointed out that the word 'Tragedy' was right there in the title.

Afterward, Father had asked Draco if he understood why they had gone to see this play.

Draco had said it was to teach him to be as cunning as Light and Lawliet when he grew up.

Father had said that Draco couldn't possibly be more wrong, and pointed out that while Lawliet had cleverly concealed his face there had been no good reason for him to tell Light his name. Father had then gone on to demolish almost every part of the play, while Draco listened with his eyes growing wider and wider. And Father had finished by saying that plays like this were always unrealistic, because if the playwright had known what someone actually as smart as Light would actually do, the playwright would have tried to take over the world himself instead of just writing plays about it.

That was when Father had told Draco about the Rule of Three, which was that any plot which required more than three different things to happen would never work in real life.

Father had further explained that since only a fool would attempt a plot that was as complicated as possible, the real limit was two.

Draco couldn't even find words to describe the sheer gargantuan unworkability of Harry's master plan.

But it was just the sort of mistake you would make if you didn't have any mentors and thought you were clever and had learned about plotting by watching plays.

"So," said Harry, "what do you think of the plan?"

"It's clever..." Draco said slowly. Shouting brilliant! and gasping in awe would have looked too suspicious. "Harry, can I ask a question?"

"Sure," said Harry.

"Why did you buy Granger an expensive pouch?"

"To show no hard feelings," said Harry at once. "Though I expect she'll also feel awkward if she refuses any small requests I make over the next couple of months."

And that was when Draco realized that Harry actually was trying to be his friend.