"Harry," Draco said in the middle of the old man translating a list of all eleven powers of a beholder's eyes, "what does this mean?"
Harry held up a finger and the old man finished the list.
Then Harry thanked all the portraits for helping - Draco, pretty much on automatic, did so as well and more graciously - and they headed back to the classroom.
And Harry brought out the original parchment with the hypotheses, and began scribbling.
Observation:
Wizardry isn't as powerful now as it was when Hogwarts was founded.
Hypotheses:
1. Magic itself is fading.
2. Wizards are interbreeding with Muggles and Squibs.
3. Knowledge to cast powerful spells is being lost.
4. Wizards are eating the wrong foods as children, or something else besides blood is making them grow up weaker.
5. Muggle technology is interfering with magic. (Since 800 years ago?)
6. Stronger wizards are having fewer children. (Draco = only child? Check if 3 powerful wizards, Quirrell / Dumbledore / Dark Lord, had any children.)
Tests:
A. Are there spells we know but can't cast (1 or 2) or are the lost spells no longer known (3)? Result: Inconclusive due to Interdict of Merlin. No known uncastable spell, but could simply have not been passed on.
B. Did ancient first-year students cast the same sort of spells, with the same power, as now? (Weak evidence for 1 over 2, but blood could also be losing powerful wizardry only.) Result: Same level of first-year spells then as now.
C. Additional test that distinguishes 1 and 2 using scientific knowledge of blood, will explain later. Result: There's only one place in the recipe that makes you a wizard, and either you have two papers saying 'magic' or you don't.
D. Are magical creatures losing their powers? Distinguishes 1 from (2 or 3). Result: Magical creatures seem to be as strong as they ever were.
"A failed," said Harry Potter. "B is weak evidence for 1 over 2. C falsifies 2. D falsifies 1. 4 was unlikely and B argues against 4 as well. 5 was unlikely and D argues against it. 6 is falsified along with 2. That leaves 3. Interdict of Merlin or not, I didn't actually find any known spell that couldn't be cast. So when you add it all up, it looks like knowledge is being lost."
And the trap snapped shut.
As soon as the panic went away, as soon as Draco understood that magic wasn't fading out, it took all of five seconds to realize.
Draco shoved himself away from the desk and stood up so hard that his chair skittered with a scraping noise across the floor and fell over.
"So it was all just a stupid trick, then."
Harry Potter stared at him for a moment, still sitting. When he spoke, his voice was quiet. "It was a fair test, Draco. If it had come out a different way, I would have accepted it. That's not something I would ever cheat on. Ever. I didn't look at your data before I made my predictions. I told you up front when the Interdict of Merlin invalidated the first experiment -"
"Oh," Draco said, the anger starting to come out into his voice, "you didn't know how the whole thing was going to come out?"
"I didn't know anything you didn't know," Harry said, still quietly. "I admit that I suspected. Hermione Granger was too powerful, she should have been barely magical and she wasn't, how can a Muggleborn be the best spellcaster in Hogwarts? And she's getting the best grades on her essays too, it's too much coincidence for one girl to be the strongest magically and academically unless there's a single cause. Hermione Granger's existence pointed to there being only one thing that makes you a wizard, something you either have or you don't, and the power differences coming from how much we know and how much we practice. And there weren't different classes for purebloods and Muggleborns, and so on. There were too many ways the world didn't look the way it would look if you were right. But Draco, I didn't see anything you couldn't see too. I didn't perform any tests I didn't tell you about. I didn't cheat, Draco. I wanted us to work out the answer together. And I never thought that magic might be fading out of the world until you said it. It was a scary idea for me, too."
"Whatever," Draco said. He was working very hard to control his voice and not just start screaming at Harry. "You claim you're not going to run off and tell anyone else about this."
"Not without consulting you first," Harry said. He opened his hands in a pleading gesture. "Draco, I'm being as nice as I can but the world turned out to just not be that way."
"Fine. Then you and I are through. I'm going to just walk away and forget any of this ever happened."
Draco spun around, feeling the burning sensation in his throat, the sense of betrayal, and that was when he realized he really had liked Harry Potter, and that thought didn't slow him down for a moment as he strode toward the classroom door.
And Harry Potter's voice came, now louder, and worried:
"Draco... you can't forget. Don't you understand? That was your sacrifice."
Draco stopped in midstride and turned around. "What are you talking about?"
But there was already a freezing coldness in Draco's spine.
He knew even before Harry Potter said it.
