"I'm not arguing with that," Harry said quietly. "But will you say that Lily Potter's death was sad? Just say that one thing?"
"That's..." Draco was having difficulty finding words again. "I know, I know how you feel, but don't you see Harry, even if I just say that Lily Potter's death was sad, that's already going against the Death Eaters!"
"Draco, you've got to be able to say the Death Eaters were wrong about some things! You have to, you can't progress as a scientist otherwise, there'll be a roadblock in your way, an authority you can't contradict. Not every change is an improvement, but every improvement is a change, you can't do anything better unless you can manage to do it differently, you've got to let yourself do better than other people! Even your father, Draco, even him. You've got to be able to point to something your father did and say it was mistaken, because he wasn't perfect, and if you can't say that, you can't do better."
Father had warned him, every night before he went to sleep for a month before he went to Hogwarts, that there would be people with this goal.
"You're trying to break me loose of Father."
"Trying to break a part of you loose," said Harry. "Trying to let you fix some things your father got mistaken. Trying to let you do better. But not... trying to break your Patronus!" Harry's voice got softer. "I wouldn't want to break something bright like that. Who knows, fixing Slytherin House might need that, too..."
It was getting to Draco, that was the thing, despite everything it was getting to him, you had to be really careful around Harry because his arguments sounded so convincing even when he was wrong. "And what you're not admitting is that Dumbledore told you that you could avenge your parents' deaths by taking Lord Malfoy's son from him -"
"No. No. That part's just wrong." Harry took a deep breath. "I did not know who Dumbledore was, or who the Dark Lord was, or who the Death Eaters were, or how my parents died, until three days before I came to Hogwarts. The day you and I first met in the clothes shop, that was the day I learned. And Dumbledore doesn't even like Muggle science, or he says he doesn't, I got a chance to probe him on it once. The thought of taking revenge on the Death Eaters through you has never crossed my mind, not even once until now. I didn't know who the Malfoys were when I met you in the clothes shop, and then I liked you."
There was a long silence.
"I wish I could trust you," Draco said. His voice was shaking. "If I could just know you were telling the truth, everything would be so much simpler -"
And then suddenly it came to Draco.
The way to know whether Harry Potter really meant everything he said, about wanting to fix Slytherin House, about being sad that Mother had died.
It would be illegal, and since he'd have to do it without Father's help, it would be dangerous, he couldn't even trust Harry Potter to help, but...
"All right," Draco said. "I've thought of a definitive experiment."
"What is it?"
"I want to give you a drop of Veritaserum," Draco said. "Just one drop, so you can't lie, but not enough to make you answer anything. I don't know where I'll get it, but I'll make certain it's safe -"
"Um," Harry said. There was a helpless look on his face. "Draco, um -"
"Don't say it," Draco said. His voice was firm and calm. "If you say no, that's my experimental result right there."
"Draco, I'm an Occlumens -"
"OH THAT IS SUCH A LIE -"
"I was trained by Mr. Bester. Professor Quirrell set it up. Look, Draco, I'll take one drop of Veritaserum if you can get it, I'm just warning you that I'm an Occlumens. Not a perfect Occlumens, but Mr. Bester said I was putting up a complete block, and I could probably beat Veritaserum."
"You're in your first year at Hogwarts! That's just crazy!"
"Know a Legilimens you can trust? I'll be happy to demonstrate - look, Draco, I'm sorry, but doesn't the fact that I told you count for something? I could have just let you do it, you know."
"WHY? Why are you always like this, Harry? Why do you have to mess everything up even when it's IMPOSSIBLE? And stop smiling, this isn't funny!"
"I'm sorry, I'm sorry, I know it's not funny, I -"
It took a while for Draco to get himself under control.
But Harry was right. Harry could have just let Draco administer the Veritaserum. If he really was an Occlumens... Draco didn't know who he could ask to try Legilimency, but he could at least ask Professor Quirrell if it was true... Could Draco trust Professor Quirrell? Maybe Professor Quirrell would just say anything Harry asked him to.
Then Draco remembered the other thing Harry had told him to ask Professor Quirrell, and thought of a different test.
"You know," said Draco. "You know what it costs me, if I agree that the poison in Slytherin's House is hating Muggleborns, and say that Lily Potter's death was sad. And that's part of your plan, don't tell me it's not."
Harry said nothing, which was wise of him.
"There's something I want from you in return," said Draco. "And before then, an experimental test I want to try -"
Draco pushed open the door to which the portraits had directed them, and this time it was the right door. Before them was a small empty place of stone set against the night sky. Not a roof like the one he'd dropped Harry from, but a tiny and proper courtyard, far above the ground. With proper railings, elaborate traceries of stone that flushed seamlessly into the stone floor... How so much artistry had been infused into the creation of Hogwarts was something that still awed Draco every time he thought about it. There must have been some way to do it all at once, no one could have detailed so much piece by piece, the castle changed and every new piece was like that. It was so far beyond the wizardry of these fading days that no one would have believed it if they hadn't seen the proof in Hogwarts itself.
Cloudless and cold, the winter night sky; it got dark long before students' curfew, in the final days of January.
The stars shining brightly, in the clear air.
Harry had said that being under the stars would help him.
Draco touched his chest with his wand, slid his fingers in a practiced motion, and said, "Thermos." A warmth spread through him, starting from his heart; the wind went on blowing on his face, but he was no longer cold.
"Thermos," Harry's voice said behind him.
They went together to the railing, to look down at the ground a long way below. Draco tried to figure if they were in one of the towers that could be seen from outside, and found that right now he couldn't quite seem to picture how Hogwarts looked from outside. But the ground below was always the same; he could see the Forbidden Forest as a vague outline, and moonlight glittering from the Hogwarts Lake.
"You know," Harry's voice said quietly from beside him where his arms leaned on the railing next to Draco's, "one of the things that Muggles get really wrong, is that they don't turn all their lights out at night. Not even for one hour every month, not even for fifteen minutes once a year. The photons scatter in the atmosphere and wash out all but the brightest stars, and the night sky doesn't look the same at all, not unless you go far away from any cities. Once you've looked up at the sky over Hogwarts, it's hard to imagine living in a Muggle city, where you wouldn't be able to see the stars. You certainly wouldn't want to spend your whole life in Muggle cities, once you'd seen the night sky over Hogwarts."