Snape stared at Harry a long time before grabbing him roughly by the upper arm and dragging him toward the door. “I don’t know who you are, but you are not Harry Potter.”

Harry sighed as he stumbled silently along beside the Potion’s master. At least this would not be out of character for either of them, Harry thought ruefully. Getting dragged down the castle’s corridors by Snape for some unforgiveable infraction would seem perfectly ordinary to anyone who witnessed it.

 “We will see what the Headmaster has to say about this,” Snape declared.

Harry said nothing. He watched impassively as Snape gave the password and the gargoyles leapt aside. Snape tightened his grip even more as they rode the rotating staircase up to Dumbledore’s office. Harry bit his lip, refusing to complain about the pain in his arm from Snape’s too-tight grip.

“Ah, Severus, Harry. To what do I owe the pleasure of your company?”

“This. Is. Not. Harry. Potter.” Snape bit out, chewing off each word as if it were poisonous. “This imposter turned up in my class. He clearly knows more about Potions, and other things,” he added derisively, “then Potter ever could.”

Dumbledore looked bemused at Snape’s pronouncement. “Is this true?” he asked of Harry.

“Yes, and no,” Harry replied. “I am Harry Potter. But I am from 4 years in the future.”

The twinkle in Dumbledore’s eyes vanished as his expression hardened into one of distrust. “And how is it that you managed to travel back in time?” Dumbledore asked.

“I died.”

“I see,” Dumbledore said, shuffling some papers on his desk. “So, you came back to avoid your own death?” Dumbledore asked.

Harry stared at the headmaster. He knew this was some sort of test. The man didn’t see at all. “No,” Harry replied. “I came back to avoid…” Harry clamped his mouth shut, cutting off the words that he was about to say. Your death, he thought. Both of your deaths, he clarified internally, including Snape in the equation. Sighing, he said instead, “You once said that there were worse things than death. I understand that now.”

Dumbledore looked up at Harry, a spark of curiosity peeking out from behind the Headmaster’s controlled expression. “That is indeed something I might say,” he allowed.

“Headmaster,” Snape interjected, “may I suggest that we require some proof? If Potter is who he says he is, then he should not object to taking Veritaserum.”

Harry lifted a hand in protest, causing Snape to raise a suspicious brow. “I do not object outright,” Harry directed at Snape. Then he turned his attention to the headmaster, “But, you’ve also said that time travel is dangerous, and attempting to change the future even more so. I don’t want to get this wrong.”

Harry felt Dumbledore’s gaze as if it were a physical touch. The man didn’t enter Harry’s mind, yet Harry felt the older wizard studying him, measuring him. Harry forced himself to stand still beneath the man’s scrutiny. It was essential that he convince Dumbledore of not only his identity, but of the importance of his mission here.

“There is something I can offer you, something that I think will convince you…” Harry said, trailing off.

“And yet, you hesitate,” Dumbledore observed.

Harry turned to Snape. “With all due respect, sir,” Harry said earnestly, suppressing a smile at the taken aback expression on Snape’s face, “the proof I have to offer is for the headmaster’s ears alone.”

“The Potter I know…” Snape began.

“I am not the Harry Potter you once knew,” Harry interrupted. “Not anymore. So if you’ll please excuse us,” Harry said, a note of deference in his voice, “this will only take a moment.”

Snape snapped his gaze to Dumbledore, clearly uncomfortable with leaving the headmaster alone with someone he believed to be an imposter. 

“It is all right, Severus. If you could please step outside...”

“Headmaster, do you really think it wise…”

“If I need you, Severus, you are only a wand away.”

Grumbling about foolish old wizards, Snape stepped out of the office. Dumbledore returned his attention to Harry, equal parts expectant and wary.

Harry closed his eyes and took a deep breath. He hated to do this to the man, but he had no other choice. “I know about the Horcruxes,” he said. “And yes, you are right. There are more than one. There are seven, in fact.” Harry paused, giving Dumbledore a moment to process what he’d just said. The older wizard looked stunned. “I know about Grindewald, too, and your summer together in Godrick’s Hollow, and your obsession with the Deathly Hallows.” Gathering his courage, Harry delivered the final blow. “But most importantly, I know what you see when you look into the Mirror of Erised. I know about your sister, Ariana. I know how she died.”

Harry wasn’t sure what he expected. Shock? Betrayal? Anger? Whatever it was, he hadn’t expected the look of grief and guilt that crossed his beloved headmaster’s face before the wizard slumped over his desk, his head in his hands.

“I’m sorry I can’t bring her back,” Harry whispered. “But if you help me, we can save a lot of other people you care about.” Not knowing what else to say, Harry added, “That has to be worth something.”

 “You may be convinced that this intruder is Harry Potter, but I am not,” Snape declared.

“Severus,” Dumbledore replied tersely, and Harry could tell he was losing patience. “Need I remind you of your return to the Light? Need I remind you of the secret that I kept for you, that I still keep for you, while all of my staff doubt your loyalty because you refuse to let me enlighten them?”

“Sir,” Harry directed at Snape, trying to ease the tension in the room. “I know that I seem different to you. I am different. I am not the irresponsible, unaccountable-for-his-actions kid I used to be. I’d like to say I’m no longer a rule-breaker, but that wouldn’t be true,” Harry ran his hands through his hair, not sure he was making any headway with the surly Potions master. “Regardless of all that, I am still Harry Potter, and I am here because I need your help. We need your help,” Harry said, including Dumbledore in his statement with a sweep of his arm.

Snape stood rigid, arms crossed tightly over his chest, radiating doubt and disbelief.

“I can tell you who’s been stealing your potion ingredients and why,” Harry continued.

“That’s because it’s you!” Snape accused.

Harry rolled his eyes. “I can also tell you how my name ended up in the TriWizard cup. More importantly,” Harry said, raising a hand to cut off Snape’s rebuttal, “I can tell you why. As I’ve already said, Voldemort is getting stronger. He plans to make his move during the third task. And if we do nothing, one of the Champions will die—and it won’t be me.”

That shut Snape up, Harry thought with momentary satisfaction. Dumbledore was looking grave.

“Before we delve into what you know, Harry, what is it that you want from us? As you said before, changing the future is a dangerous business.” Dumbledore commented.

“Last time,” Harry said, “we all went into this blind. You knew more than anyone else,” Harry said, gesturing toward Dumbledore, “but you didn’t know everything. You couldn’t know everything.”

Dumbledore sagged in his chair, the weight of realization settling heavily upon him. “Am I correct in assuming that we all suffered due to my ‘lack of knowledge’?”

“You were on the right track,” Harry said, “But yes, we suffered immensely.” Harry felt his gut tighten at the thought of Dumbledore’s death. Turning to Snape, Harry added, “And you, professor, suffered more than all of us combined.”

Snape seemed both surprised and dubious at Harry’s pronouncement. Harry doubted the thought of suffering surprised Snape; it was more likely that Harry cared about his suffering that had Snape mistrusting the situation.

“I believe,” Harry said, “that if we use what I know and we work together, we can defeat Voldemort a lot sooner this time. Perhaps we can even prevent his return. And we can avoid a lot of unnecessary deaths.”

“You mean your death,” Snape sneered, still unwilling to accept the changed Harry Potter standing before him.

“No,” Harry snapped, his impatience and temper getting the better of him. “I mean yours.”