"I... I'm sorry!" Harry cried, and meant it that time.
"Your sorries won't be worth much when your brother is a puddle of muck after a three-hundred foot fall!"
Something foul actually surged into the base of Harry's throat. He almost gagged on it before managing to swallow it back down. Ugh. He was never going to eat shrimp again.
"Let's discuss just why you've sentenced Draco to a horribly painful death," Snape remarked in a conversational tone, though his eyes still gleamed like chips of grim, black ice. "Because you trusted entirely in your sudden brilliant idea, which I must say was less than intelligent in my estimation. Didn't the headmaster address this issue with you? He told you that seer dreams always came true, that prophecy cannot be defied! But of course, he only has a mere hundred and forty years' more experience than you, so what would he know?"
"He didn't explain things very well--" Harry tried defending himself. He should have known it would be better to just keep his mouth closed.
"Oh, he didn't, did he? Is that going to be your excuse every time you refuse to listen to your elders? As I recall, you trotted out the same pathetic line over your miserable failure to master Occlumency when I first endeavored to teach you! But of course you knew better than your elders then as well, didn't you?"
"But he didn't explain," Harry insisted, determined not to get sidetracked into arguments about Snape's horrid teaching during fifth year, or what his own failure to learn had led to for Sirius. "I even asked him what would happen if I changed something so a dream couldn't happen, and he didn't answer the question, Professor!"
Snape stared at him for a long moment, and then corrected, "Severus. Or Father. Or Dad. Even furious, I am still your father, Harry."
Harry knew that, but he appreciated that Snape would say it, and in the middle of their fight, no less. He gave a jerky little nod.
"Now, as for Albus, he was probably wary of tempting fate," Snape went on in a heavy tone. "Either that, or he feared you were too young to understand the concept of paradox. I dare say you comprehend it now. Trying to defy the future has done nothing but assure it. But it wasn't only Albus you ignored in this matter, Harry. I was most specific with you on the matter of not divulging your magic to Miss Granger. Now, why was that? Could it be that I have more experience than you as well? Enough, as I said, to recognize when someone is lying?"
Harry sort of gulped. "Is that why you said not to tell her? Because you knew she did know about my magic in that dream, and you were trying to make sure it couldn't come true? What happened to the future cannot be defied?"
"I did not say I believed that, only that Albus did."
"But he doesn't believe that!" Harry blurted. "How could he, when he sent us back in time third year so I could rescue Buckbeak and save Sirius from the Dementor's kiss..." He suddenly stopped speaking, realizing what he had said. Uh-oh...
"I am going to kill that old man before all this is through," Snape abruptly announced, standing up and beginning to pace. For one awful second, Harry thought Snape was reliving his old fury over Sirius' escape, but then the man went on, "He gave you a time-turner? He gave a thirteen-year-old a time-turner, and sent him out into a forest where a werewolf was running free! Wonderful!"
"Um, but we changed the future," Harry pointed out, standing up too, and going over to where Snape had stopped, by the hearth.
"You changed the present," Snape amended. "And in any case we are not discussing time-turners, but seer dreams. If seer dreams are in fact fated as Albus believes, then even using a time-turner would be of no help; you would merely encounter another paradox."
"But you think the seer dream can be defied, and you were trying to defy it," Harry glumly concluded. "And I messed it all up."
"You see now why you might consider listening to your elders occasionally?" Snape darkly inquired.
"And Draco's going to die now?" Harry cried. "And it will be my fault! It's like with Sirius, just like you said, with the Occlumency, I didn't listen! Draco's going to end up muck and it's all my fault, isn't it!"
Snape stared at him for a long moment. "I should say yes," he gruffly admitted. "I had intended to, when I started this. Your punishment. After your outright defiance tonight, you fully deserve to believe that Draco will die because of your actions. But..." He looked away. "I find I cannot do a thing like that to my own son."
Harry looked up through bleary eyes, his face wet as he rubbed at his cheeks. "Huh?"
A hint of pity in the hard line of that mouth, now. "You already blame yourself for too much that is not your fault. I can't add more shadows to your eyes, especially not such specious ones as these."
"I don't... what do you mean?"
"Draco is not going to die, you idiot child. You appear to have forgotten something key to the whole issue: I do not believe your last few dreams predict the future."
Harry's thoughts went into a spin. Too many branching possibilities, too many paradoxes, and all of them so tangled up in lies and misdirection that he hardly knew where the truth began or ended. He finally made enough sense of all that had been said to weakly assert, "But... you said you wanted me to not tell Hermione about my magic because you were trying to stop the dream from coming true... if you were just lying about that to punish me, then why didn't you want me to tell her even that I had some weak powers? I mean, she was going to find that out anyway when I went back to class."
"I wasn't lying to punish you," Snape told him, reaching out to take his hands. Snape's were warm, astonishingly so, which made Harry realize that his own must feel frozen. "I was... overstating the case, perhaps. It is true that I wanted you to step back from your own convictions and realize what might result from your charging ahead. It is also true that when I saw in the pensieve how Miss Granger appeared to already know about your magic, though she was determined to hide it from her fellow Gryffindors, I realized how I might arrange things to ensure that the dream could not ever come to be."
"But you believe in my dream then, sir? Uh, Father?"
"No," Snape's lank hair swayed as shook his head in emphatic denial. "I do not. I do not for one instant, Harry. But just as I went and warded the Owlery with extra spells, I thought it would do no harm to ladle this layer of protection atop Draco as well. Because... I do not believe it is a seer dream, but I recognize a remote possibility that I may be mistaken." The Potions Master sighed. "I thought it would be a simple matter to keep Miss Granger fooled just a short while longer. That was all the time we needed, you realize. It was clear from your dream that events in the Owlery would transpire before you ever moved back to Gryffindor Tower."
"Let me go back tonight, then," Harry begged. "Even if you don't believe in the dream. I don't either, not really. Not even when I told Hermione. It was like you said... just in case."
"You are not ready to go back," Snape said, giving his hands a harder squeeze. "I love you both, as you well know. I would not risk you to save Draco, nor would I risk him to save you. And besides, if it is a seer dream then I think that tonight's events have shown conclusively that trying to defy it is indeed a fool's game. Sending you back early will merely create another paradox, another way for the future to manifest itself regardless."