A veritable storm of magical cleaning blew through Grimmauld Place over the first few days of the holidays, with every Marauder in residence and in need of a safe place to sleep. Even the twins weren't too bad about the process, due to the novelty of getting to cast magic outside of school.
By Friday, the last of the dangerous-looking question marks were cleared from the various rooms on Harry's guildhall map, though the true niceties of taking care of all the dust and grime might come down to Kreacher doing his job. On Harry's prompting, Sirius had formally renewed his bond of patronage with the racist elf (and was trying to be nicer), but it was hard to be certain how well it was working. They probably wouldn't know for sure until summer, once they returned again and could tell whether he'd been making progress or allowing it to fall back into disrepair. The old elf at least seemed to have some renewed pride in the house: once they'd cleared the doxies from the room with the Black's damaged family tapestry, he insisted on deep cleaning it himself.
Perhaps more importantly, they'd finally found the guild vault's physical location. It was two floors underground and built fully beneath the neighboring house behind a hidden door such that you'd never think it was there unless you were looking everywhere (and had Marauder's Map powers that could apply to any location). It was a little surprising that the guildhall map hadn't automatically given it up, such were the charms on it.
The room clearly used liberal amounts of space expansion and was still packed nearly full of neatly-stacked objects that almost completely mirrored the grid in Harry's interface. He longed to reach in for the wall of tomes right near the door, but Remus insisted, "This is the point where we get the headmaster involved."
Dumbledore merely sighed when he arrived the next day, and spotted all the children that should either be at the school or their homes lounging in Grimmauld Place's sitting room. Victorian-era furniture that was meant for uncomfortable and tense high society meetings was nonetheless being put to a game effort by teen bodies with a powerful need to sprawl and without any adult that would tell them to keep their feet off the velvet. "I don't suppose Molly and Arthur approved of this visit?" he asked Remus and Sirius, with a disapproving eyebrow.
"Didn't want to steal your thunder in catching the Old Crowd up, sir!" Sirius said with a shit-eating grin.
Putting on his catch-more-flies-with-honey twinkle, the old man nodded, simply saying, "Well, let's take a look at the vault, then I suppose everyone here should be part of the secret when I cast the Fidelius anyway…"
"What's the word about the prison, sir?" Harry asked, as he followed the adults down to the vault.
Sighing again, Dumbledore explained, "I've been most of the week explaining myself to the Wizengamot, and have mostly convinced them that our exploration of the prison happened upon a grave threat to the populace, and nothing could have been done to save the building. There are still several holdouts who, I suppose, would have preferred to be terrorized by Ekrizdis for long enough to understand the gravity of the threat. But they've begun to find the contents of the hidden floors, and some small collection of great historical value survived."
"Did they find the bodies in the basement?" Harry knew that Dawlish had been keen to get them sent to their families for burial.
"A few. Those levels are the most buried. And there was a secondary collapse, presumably coinciding with your removal of the contents of the guild vault. The Ministry really doesn't have that many members skilled enough at transfiguration to quickly shift through all the rubble, though Minerva and I have provided assistance as we are able. They are more concerned with the bodies of the prisoners," Harry winced at that reminder, "of which only a few have so far been recovered. Based on the way the building collapsed, it's possible that those high up might have been thrown clear. My old friend Auror Moody keeps insisting 'no body, no death' and trying to organize squads to patrol the coast for anyone that managed to float away."
Sirius shrugged, "I don't think anyone in that state could have survived the swim to land even if they hadn't just fallen a few hundred yards into the freezing water… but I guess I'd also like to see some of those bodies to be sure."
Dumbledore might have planned to say something else, but was distracted by Sirius opening the door to the vault and seeing the pile of magical artifacts within. Harry had already spent the last few days inspecting it from within the interface, and it was likely to be a trove of discoveries much grander than the Room of Hidden Things.
True to his character, Ekrizdis had seemingly made his apprentices store anything of value they wouldn't need every day in the guild vault rather than their rooms. While the missing children of prominent families hadn't walked off with key family relics, there was a lot of really nice stuff still present.
In addition to the skill books that Harry had saved, there was a vast array of spellbooks and family tomes that Ekrizdis hadn't left for the apprentices to keep in their personal libraries. Or perhaps he'd managed to sneak out at various points in the 500 years while the dementors had been occupied to grab key tomes from the hidden levels? Regardless, quite a few of the volumes Madam Pince had bemoaned not being at Hogwarts were available, and many that weren't even on her index besides.
A whole corner of the room was basically a jewelry store, half of it magic and half of it just ornate. Again, Harry wasn't sure how the old lich had convinced his apprentices to turn over such valuable keepsakes, but Remus figured they were kept to a simple dress code as apprentices and the jewelry they couldn't wear would be safer in the vault than in their rooms waiting for sticky fingers to take. Similarly, personal tools and furnishings such as small mirrors, musical instruments, chess boards, and the like were part of the vault, most of them magical in some way.
The rack of portraits was perhaps the most surprising find. All of them were small canvases, such that they could have been smuggled out of family homes. Still dormant, it was unclear whether they were just beloved relatives that the apprentices had wanted to have at hand to converse with, or whether they might be experts on some subject.
Several intense-looking large metal jars seemed to be potion vessels, and inspection suggested that they were heavily preserved and might still be viable. The actual contents of them were multiple individual vials sealed within one jar, so inspection hadn't given Harry any insight into exactly what powerful potions Ekrizdis had considered worth expending so much effort preserving. Could he even drink potions himself, as a walking corpse?
Finally, the vast majority of the vault was clearly materials and tools. In hindsight, Harry had no idea how much was always in the vault and how much had been in Ekrizdis' personal storage. Probably all the seemingly-fresh potions ingredients had been in the timeless void of the lich's inventory, as well as the various eggs of rare creatures (including, yes, a dragon egg, as he'd implied). He hadn't kept a personal menagerie that had made it into the vault, but a few extremely-archaic brooms and flying carpets had made it from his mounts storage, as well as a whole ornate carriage that took up one wall of the room. It was surrounded by piles of rare lumber, metal ingots, and the physical representation of the thousands of coins and even a few clusters of gems and other negotiable specie not in the form of wizarding currency.
The small pile of objects near the front of the room that represented the original Black treasures from the vault were barely noticeable by comparison.
Dumbledore simply stared at the immense magical trove for a minute and a half, then jolted himself out of his awe and started to cast detection spells. Colored wisps and ethereal runes appeared at various spaces around the room as he focused on different objects. He had an organized method to it, broad-area detection charms giving him clues to which individual objects to focus on. He then periodically frowned and levitated an item to the one empty corner of the room as he decided it was dangerous. It only took half an hour, and Harry's spellbook had filled in nearly all the way on several of the charms before the old man ceased his casting.
"Those are the ones that are in some way cursed," he gestured at the pile that was daunting but still dwarfed by all the other uncursed items. "Now I'd like to skim the book collection."
That took another hour, Dumbledore opening each of the books to ascertain the contents. Most he set back in place. Some he stacked to the side with a forbidding look and references to banned magics. A few he set in another pile, which Harry took to be the ones that he was extremely interested to get to read. Finally, he summed up, "I harbor no regrets about the destruction of Ekrizdis. Several of the books he penned as core education for his apprentices look to be deeply troubling. I would not have their words infesting your mind, Harry. The rest, however, seem reasonable reading material."
"And that stack?" Sirius gestured at the ones he'd set aside that weren't dark.
"Consider it an old man's due for his recent efforts," his beard twitched in a smile. "None of them are from the Black library, and they are on topics of great interest to me. Harry can, of course, check them to see if they're skill books before I make off with them, as they say."
Harry just shrugged at Sirius' glance. The headmaster really was doing them some pretty big favors not demanding everything they'd gotten be sent to Hogwarts or the Ministry. That reminded him, "What do we do with the cursed stuff and the dark magic books?"
"I've brought an extended knapsack," he explained. "I suppose I can dispose of the most insidious objects and then replace the rest in the ruins of Azkaban when we dig deep enough. That should go a long way to convincing any doubters of the danger that was averted."
"And it's not even really lying," Remus approved. "Those things were inside."
"Well, a few, I think, might have originally been Black treasures that hopefully Sirius will be glad to see gone," the old man agreed. "But it's best to base political moves on the truth, for a variety of reasons. Now, let's see about that Fidelius!"
The Fidelius Charm was an involved one. Because Sirius, Harry, and Kreacher would actually be living at the house, they were the focus, while the rest of the Marauders had to wait in the park across the street lest they be thrown into confusion once they were inside of a home they suddenly couldn't perceive. Calling it a charm was a stretch, Harry thought, since it was basically a whole piece of ritual magic. Circles were drawn on the floor, invocations were recited, and candles were burned. When it was done, the candles flared out, but otherwise Harry couldn't tell the difference other than checking the guildhall menu to make sure that the feature had been added.
He could tell something had happened when they walked outside to see Remus, Fred, George, Lee, Ron, Hermione, and Ginny milling about the park in confusion. "Harry! I can't remember exactly why we were waiting in the park!" Hermione nearly wailed, having grown to rely on her maxed-intellect-and-willpower mind being immune to manipulation of any sort.
"A common side effect, I apologize," Dumbledore assured her, motioning for everyone to gather close together so he could whisper to them, "The headquarters of the Marauders may be found at number twelve, Grimmauld Place, London."
"Oh. Of course," Hermione agreed, eyes crossing as her memories linked back up. "Only, headmaster, does this mean that the charm affects information, rather than our minds? Because I should be basically immune to mind magic, and that's worrisome for other types of things you might do with that power."
"I shall direct you to the books on magical information theory when we return to the school," he suggested, to stem the tide of questions. "I suggest, in the meanwhile, that everyone returns to the building, which should now be one of the most secure sites in Britain. I must gather the dark artifacts and head on my own way."
"And I'm good to check the skill books, sir?" Harry confirmed.
"I look forward to hearing just how much they taught you on your own return to Hogwarts," the old man agreed.
Please enjoy this chapter as my gift to you for the holidays. I'm hoping to start posting again regularly soon, but my buffer still isn't where I want it to be. I'm also hoping FFnet's gift to ME will be fixing the stats soon (if you're wondering why the updates have diminished across the whole site, it's likely because no authors have gotten any statistics on readership for months now). So please review and let me know what you're enjoying and what you want to see more of: right now, it and favorite/follow notifications are my only clue that anyone is reading!