Harry felt strangely nervous as he stepped over the broken guardian at the base of the stairway leading up to the headmistress's office, and climbed the moving stairs. He and Luna had made it to Hogwarts, without incident and managed to avoid talking to anyone—despite the clean-up crews still milling around in large numbers—Harry, through judicious use of his Invisibility Cloak, and Luna by simply ignoring everyone that tried to get her attention.
When they opened the door at the top of the stairs, the newly appointed Headmistress McGonagall looked up from the paperwork she was sorting through on the large desk, "Good morning, Mr Potter, Miss Lovegood. To what do I owe the pleasure of today's visit? Have you come to volunteer to lend a hand?"
"Good morning, Professor—I mean Headmistress—no—I mean sorry—I mean we’re not here about the cleanup. I was hoping—I mean… do you think we could have a few minutes alone in your office with Headmaster Dumbledore's portrait, please," Harry stumbled through his response.
Luna ignored the question in favour of wandering over to the Headmistress’s bookshelves, and admiring the collection of books amassed by several centuries of headmasters.
For a moment McGonagall looked as though she might be offended, but then she nodded curtly, "Certainly, Mister Potter." She gathered up some papers and turned to leave, "I shall be in the teacher's lounge if you should need me."
"Thank you, Headmistress," said Harry. As she made her way out of the room, he took a moment to look around. Not much had changed. Aside from the Pensieve being back where it belonged, and the desk being slightly tidier, the room was exactly as Harry remembered the morning after the final battle.
The realization caused a pang of sadness to rise up within and it was a moment before he recovered his composure enough to address the sleeping portrait he had come to see, "Professor Dumbledore?"
The portrait startled awake. “Oh, good day, Mr Potter, and it seems that you’ve brought Miss Lovegood with you.” He nodded in the direction of Luna who had now wandered away from the bookshelf and was instead inspecting some of his trinkets. “Am I to understand that she’ll be joining you on your quest?”
Luna nodded enthusiastically, “Yes, Headmaster! Harry invited me to help him break into a high-security, top-secret ICW base in Antarctica, and re-write history.”
“Break-in?” asked Dumbledore, “The ICW hasn’t given their permission then?”
Luna shook her head, “They're all infected with vanusgenes!”
“They gave all kinds of fancy reasons, but I’m pretty sure the real reason is politics,” added Harry. “So... Luna and I have decided to give it a go on our own. That’s one of the reasons we wanted to talk to you: do you know where it is, exactly? Marie Byrd Land is huge!"
Luna nodded, and added, “Yes it’s hundreds of millions of acres, and a lot of that is mountains.”
The portrait shook his head, "I'm afraid I can't help you with that, Harry. All I know is that it's hidden somewhere in Marie Byrd Land. I tried to avoid knowing too many specifics, in order to cut down on the many temptations involved in the Ring."
"I was afraid you might say that," Harry sighed. "What about the defences?"
"I only know that they aren't very extensive. The International Confederation of Wizards is relying mostly on the location's remoteness, inhospitable climate, and secrecy, as well as the Ring's natural defences, which are reputed to destroy anyone who tries to put it to nefarious use, as I mentioned before.
“The strongest wards in place are the Muggle Repelling ones. You won't be able to approach by Muggle vehicle. I'd probably recommend cold weather dogs as preferred method of transportation—the Muggles have banned them on the continent, but I'm sure you and Miss Lovegood can transfigure something for your use."
Harry glanced sideways at Luna; Tranfiguration wasn’t his strong-suit.
“Don’t worry about that, Harry,” she reassured him, and then as if to prove her point, she pointed her wand at the trinket she’d been examining, transforming it nearly effortlessly into a calico cat. “See?”
Harry did see, but before he could respond, the newly transfigured cat leapt from the shelf it sat on to another, causing several fragile items to fall to the ground and shatter.
Twenty minutes, and numerous bloody scratches later, Harry finally managed to catch the beast and hold onto it long enough for Luna to reverse the transfiguration. It took another twenty minutes to repair all the damage it had caused to the office and its contents in that short time.
Finally, a slightly dishevelled, but no longer bleeding Harry collapsed into the headmistress’s chair and turned back to the portrait, "We have a few more questions…”
"I can certainly try to answer them," answered the portrait, good-naturedly.
"First off, I’m confused about the Fidelius Charm," began Harry, "If the only people that could find our home in Godric's Hollow, were those that Pettigrew shared the secret with, how did Hagrid find me? And what about the hundreds of well-wishers that wrote on the sign in front of the house? They couldn’t have all been in on the secret. Did the Charm fall? And how? The Fidelius on Headquarters survived even after you died.”
"Yes, Harry, it fell with the death of your parents," confirmed Dumbledore. "The strength of a Fidelius Charm depends not only on the continued existence of the Secret Keeper, but also on the perseverance of the secret. As long as the secret continues to be true the Charm will persevere, regardless of the state of health of the Secret Keeper. Otherwise, it would be a simple matter of killing the Secret Keeper, to find one's prey.
"It’s impossible to be sure without knowing the exact words used but, in your case, I believe the Fidelius fell after the death of both your parents, when the secret went from being something along the lines of, 'The Potter family is hiding in their cottage in Godric's Hollow...' to being 'Harry Potter is hiding in his cottage in Godric's Hollow...' The charm failed to adapt to the change and thus, it fell," explained Dumbledore.
"So, no one except those that Pettigrew had shared the secret with could have found my home until both my parents were dead," repeated Harry.
"Most likely," agreed Dumbledore. "Depending on the wording, it is also possible that the Charm died when your father did."
"I don't suppose you know who Pettigrew shared the secret with, aside from Voldemort?”
"Only that I was not included."
"What about me?" asked Harry, "Would Pettigrew have had to share the secret with my parents and me, or were we immune because we were the secret?"
"No," answered Dumbledore, "He would definitely have had to share the secret with you and your parents—much in the same way that each member of the Order had to been told the location of Headquarters—for you to be able to see and recognize each other, and to be able to enter your own home."
"So I should still be able to find my family home, even if I travel back in time to before my parents died—to when the Fidelius Charm was still active?" asked Harry.
"Almost certainly," said Dumbledore.
"Travelling through time, as you plan to do involves a large series of unknowns, such that it is impossible to know anything for sure. However, I can foresee no circumstances that are likely to wipe that knowledge from your mind, especially now that you’ve been there as an adult and know where it is."
“But Harry would have to go alone?” Luna’s interruption startled Harry; she’d wandered off again midway through the headmaster’s explanation, and he’d almost forgotten she was there. “I wouldn’t be able to go with him?”
The headmaster shook his head, “No, you wouldn’t be able to get through the wards, or see through the Charm.”
Harry nodded, "Makes sense. And if I decided to evacuate the Potters to Hogwarts before Voldemort shows up, would that cause the Charm to fall?"
Dumbledore nodded, then shook his head, "It depends on the phrasing of the secret. For instance, if we take my previous example, 'The Potter family is hiding in their cottage in Godric's Hollow...' the charm will almost certainly fall, the moment they are no longer hiding there. If however, the secret was a little more versatile, for instance, 'The Potter family lives in a cottage in Godric's Hollow...' simply relocating temporarily, would not affect the strength of the charm."
Harry nodded, "Okay, so I can’t evacuate my parents without asking them what words they used. There goes the stun first, answer questions later approach…I—”
“Why do you have to ask them?” Luna cut him off, as she opened the cabinet where Harry had found the headmaster’s Pensieve the night of the final battle.
“Well, I don’t think asking Pettigrew would go over too well, Luna.”
“No, that’s not what I mean. You already know the secret, Harry,” she gestured to the Pensieve.
Harry looked puzzled for a moment. “No, I don’t…or I do, but I don’t remember…Oh! Is there some way I can make myself remember something that happened when I was a baby, Headmaster? Would the Pensieve work?” he asked.
"No, you need be able to consciously recall at least the vague details of an incident to be able to collect the memories for Pensieve viewing,” answered Dumbledore. “Childhood memories are a generally considered tricky business. There's a reason Obliviating youngsters is frowned upon. Some Mind Healers have had limited success with a rather complicated meditation technique called Peithomancy. There’s a rather specialized potion involved, followed up by inducing a meditative trance, and then asking the patient questions to encourage recall. I’ve also heard some cases of it being combined with Legilimency when conscious recall is particularly difficult."
“And where am I going to find a Mind Healer I can trust and that won’t go blabbing to the papers the minute I leave their office?” asked Harry.
“All Healers take an oath to practice their craft ethically and to protect the privacy of their patients,” reassured Dumbledore.
"Thanks Headmaster, I’ll have to think about it.” Harry hesitated, unconvinced. He didn’t like the idea of letting a stranger riffle through his memories, but it was worth considering if it would help them plan ahead better.
"So if I can evacuate them without breaking the Charm, is there somewhere safe they could hide without being seen? A Portkey to somewhere in the castle?" he continued with their previous line of discussion.
Dumbledore shook his head, "The only person that can set up a Portkey anywhere on the grounds is the current Headmaster or Headmistress—if it were as simple as that, Voldemort would have attacked Hogwarts much sooner than he did," Dumbledore explained.
"So how then did Barty Crouch Junior make a Portkey to the graveyard during the Third Task of the Triwizard Tournament?" asked Harry.
Dumbledore sighed, "Crouch only succeeded as he did because the cup was already a Portkey. I had charmed it to deliver the winner onto the podium, at the end of the Task. Since the Portkey had originally been cast by Hogwart's Headmaster, the wards permitted it to work, even after Crouch had managed to alter its destination.
“Of course there is nothing preventing you from depositing them somewhere outside the wards—the Shrieking Shack, for instance..."
“The Shrieking Shack is haunted by tormented souls,” interrupted Luna.
“No, it isn’t,” said Harry. When she looked unconvinced, he added, “I’ll explain later.”
He looked back to the Headmaster, "Do you remember what the password to your office was on October 31st, 1981? In case I need to speak to you..."
The portrait paused for a moment, deep in thought, "Alas, even my recall is not perfect. I do like to choose Halloween themed sweets as my password around that time of year, but...it was sixteen years ago..."
Harry sighed, but then moved on; it had been a long shot… "Okay... next question: How did you get to Marvolo Gaunt's ring? And what should I do differently, if I don’t want to lose a hand in the process?"
Harry was pleasantly surprised when Dumbledore proceeded, without argument or deflection, to describe the defences in far more details than he had ever been willing to share with Harry back when he had been alive, ending with, “As for how to avoid losing your hand; I would advise against touching the ring with your bare skin, and most importantly against slipping it onto a finger, regardless of how tempting it may seem—though perhaps less so for yourself who already possesses and controls this world's version of the Resurrection Stone."
"Any ideas how I might get my hands on Hufflepuff's Cup, without breaking into Gringotts?" asked Harry, filing away the information for later use.
“We’re not going to break into Gringotts?” asked Luna, sounding disappointed, before the Headmaster could respond.
Harry glared at her, hadn’t they already covered this issue? He took a few calming breaths before responding, through clenched teeth, “No, we are not breaking into Gringotts—unless it’s absolutely unavoidable.”
Harry’s anger was diffused by Dumbledore’s response, "I agree with Mr Potter, breaking into Gringotts should be considered only as a last resort. The best advice I can offer, would be to somehow convince one of the Lestranges to remove the cup themselves; the goblins are notoriously uncooperative with the Ministry with regards to providing access to the vaults of their patrons, even in cases where it is suspected they contain stolen property.”
Harry smiled wryly, "Thanks anyways, Headmaster.”
He turned to Luna, “Can you think of any questions I missed?” When she responded in the negative he continued, "We probably won't be coming back again; so, thanks for everything, Headmaster..."
"Good luck, Harry, and farewell," responded the wizard in the portrait.
Luna followed as Harry turned to leave. Halfway down the stairs he pulled his cloak back on; not only did he not want to be intercepted, he’d also rather not have to explain his current appearance.
As they crossed the grounds in silence, he allowed himself to contemplate the next step along the path they were forging. This was it, from here on out they were on their own.