Chapter Twenty: The Hogwarts Underground

The kitchen at number twelve, Grimmauld Place was cleaner than it had been in years. The walls and floors were sparkling, the formerly grimy fireplace was completely free of soot, and the copper pots and pans hanging from the ceiling had all been polished, and now positively gleamed in the firelight.

It was extremely difficult for Sirius to admit, but credit for the drastic improvement was owed almost entirely to Kreacher. The house-elf he had hated for most of his life had undergone a dramatic personality shift ever since the elimination of the locket Horcrux, fulfilling the final order given to him by his favourite master — Sirius's brother Regulus.

Further confusing his feelings regarding the old elf was Kreacher's recent habit of speaking about Harry in reverent tones, viewing Sirius's godson as the one primarily responsible for the locket's destruction. While the elf hadn't completely lost his curmudgeonly demeanour, he had been working hard to bring the house back into good condition, especially once Sirius had informed him that Harry would be returning to stay during the holidays.

On that point, Sirius could hardly blame Kreacher. If he were being honest with himself, the only thing keeping him going at the moment was the prospect of getting to spend another month with his godson. That feeling had only intensified after Kingsley had shown him a copy of The Quibbler that morning. Ever since he'd read the interview, Sirius wasn't sure whether he wanted to shake Harry's hand, or wrap him in cotton wool and hide him away until the war was over.

"What do you think, Padfoot?" asked Remus, breaking Sirius out of his reverie.

"Hmm?"

Remus looked at him speculatively. "I asked if you thought Snape would have any real news this time," he repeated.

"Who knows?" replied Sirius, as members of the Order slowly filtered into the kitchen. "My guess is he'll manage to drone on and on for half an hour without reporting anything useful."

"So, the usual, then?" smirked Remus, prompting a snort out of Sirius.

"You said it, not me, Moony," he muttered, just as Dumbledore was walking into the room.

"Good evening, everyone," he greeted them all, calling the meeting to order. "Thank you all for coming. First things first; has there been any new activity in the corridor outside the Department of Mysteries?"

"Not a peep, Albus," replied Moody, "which isn't all that surprising. We expect them to try a different strategy, after putting Sturgis under the Imperius Curse didn't pan out for them."

"Any progress on Sturgis's appeal?" asked Dumbledore.

"It's not looking good," said Arthur Weasley. "I expect he'll wind up serving the entire six-month sentence."

"That is most unfortunate," sighed Dumbledore. "Any other news from the Ministry?"

"Madam Bones has been rather tight-lipped about her investigation into the Diggory boy's death," reported Kingsley Shacklebolt. "I've heard that the Minister was working very hard to shut it all down, but all signs point to the investigation going forward."

"Very well," replied Dumbledore, nodding approvingly. "Let us hope the Diggorys are able to find some closure. Severus?"

"The Dark Lord is growing impatient," drawled Snape. "Between the aforementioned Ministry investigation and Potter's foolish article, he is beginning to question the value of remaining in the shadows."

"That is indeed concerning," replied Dumbledore.

"I thought Harry's interview was a stroke of genius," Sirius interjected. "What's wrong with putting a little heat on the other side for once? Why shouldn't Harry fight back against the Ministry's lies?"

"Because, Black," sneered Snape, "the moment the Dark Lord decides to come out into the open, we will be entering a state of open warfare. Now, because of Potter's constant need to see his name in headlines, the only thing preventing that is the Dark Lord's desire to obtain the object currently being guarded by the more useful members of the Order."

Remus had to put his hand on Sirius's shoulder to keep him from standing and going after Snape.

"I tend agree with Sirius's point of view on this," admitted Dumbledore. "It is very difficult to build a resistance whilst the Ministry continually asserts that there is no one to resist. While Severus's point also has merit, I believe the truth becoming public will be beneficial."

"In any case, we should not be surprised if the Dark Lord makes a move in the near future," continued Snape. "I do not expect an open declaration yet, but the Dark Lord's patience is limited."

"Any ideas around potential targets?" questioned Moody.

"He could, of course, choose to take the object from the Ministry by force, although I do not believe that likely at this time," answered Snape. "There are several of his followers still in Azkaban, yet again, a breakout at this time would be a considerable risk. I suspect it will be a smaller target, perhaps an obstacle he wishes to see removed."

"Like the Minister?" asked Molly Weasley.

"Eventually, perhaps," responded Snape, barely hiding his disdain. "For now, Fudge's denial of the Dark Lord's return is too convenient to throw away. Bones is the far more likely target, as are the more high-profile members of the Auror department."

"Thank you, Severus," said Dumbledore. "Do you have anything else to report?"

"No, Headmaster."

"Very well; then we shall adjourn for the evening," said Dumbledore. "Please see Alastor for the latest guard schedule, and we shall reconvene one week from today."

At the conclusion of the meeting, several Order members lingered in the kitchen, either continuing their earlier conversations or simply catching up with one another. Sirius, however, made a beeline for Dumbledore before the headmaster could depart.

"How's Harry?" Sirius asked without preamble.

Dumbledore smiled kindly at the man. "Harry is doing wonderfully," he assured him. "While the circumstances surrounding him have never been more difficult, he has repeatedly risen to the challenge, as he so often does. He has also become quite resourceful, as you have no doubt noticed."

"You're not kidding," chuckled Sirius. "That interview…"

"It was a very trying ordeal that Harry survived that night," Dumbledore said solemnly. "What he has achieved at his young age is more remarkable than most anyone will ever know."

"More people should know," countered Sirius.

Dumbledore bowed his head slightly, as if conceding the point. "You will be happy to hear that he has been putting your lessons from the summer to good use," he said, a bit more brightly.

Sirius grinned slightly.

"Found out about that, did you?"

"Indeed," the professor chuckled. "I have been working with him myself this year. While I generally approve of your training together during the holidays, I do have one concern."

"Oh?"

"While Harry was here, did he ever express a desire to learn Dark Magic?"

There was a long pause between them as Sirius considered how best to answer the question. "Not in so many words," he said finally, "but he was worried about surviving against Death Eaters using only what he knew. Why, has something happened?"

"Not one thing in particular, but there are signs, if one knows what to look for," Dumbledore replied vaguely. "I am merely asking out of an abundance of caution. And you are certain he did not learn anything Dark in nature whilst he was here?" he enquired pointedly.

"You saw this place before; who knows what he came across while Molly had them cleaning?" replied Sirius. "All I can tell you is that I never taught him anything Dark, and I wouldn't have even if he asked."

That last part, at least, was the truth, but Dumbledore's concerns didn't sit well with Sirius — in part because he still felt guilty about giving Harry that book. While he had laboured over that decision, he ultimately decided that he had already disappointed his godson enough. At the time, he felt like giving him the book was somehow better than teaching Harry himself. Had that been a mistake?

Sirius shook his head at the thought. "Harry's a good kid," he contended. "I don't know what's going on that has you so concerned, but he always winds up doing the right thing."

"On that much we can agree," replied Dumbledore. "Thank you, Sirius. I must be getting back to Hogwarts, but I shall pass on your regards to Harry," he said, and then took his leave.

oOoOoOo

It had been one week since his interview with Rita Skeeter was published in The Quibbler, and Harry was still getting used to the school's shift in attitude towards him. He knew he should be used to it, after flip-flopping between hero and pariah for much of his school career, but it never got any easier.

As expected, Umbridge's ban had been a complete and utter failure, as there wasn't a single person in the school who hadn't read the article. According to Luna, that phenomenon wasn't limited to Hogwarts, either.

"Daddy's reprinting," she had told him. "He said he's never seen anything like it — people seem even more interested in your story than the Crumple-Horned Snorkack!"

Luna went on to mention that her father had sold Harry's interview to a few other European newspapers, giving them an unexpected windfall that would easily finance their planned trip to Sweden to search for the elusive creature. Not knowing what else to do, Harry congratulated her, while deftly avoiding being drawn into a conversation about Snorkacks or any other fanciful topics.

Detention with Professor McGonagall had also been an unexpected boon. Harry knew McGonagall was a true master of Transfiguration, of course, but the effortless skill she had displayed during their evening sessions caused him to see his professor in a whole new light.

Their final session the previous evening had been a true revelation. She had challenged Harry to a duel using only transfiguration, which admittedly did not play to his strengths. After she had soundly defeated him — and in relatively no time at all — they held a rematch. And then another, and another, and another, until Harry was left lying on the floor in a sweaty heap.

"Well done, Potter," McGonagall had said at the conclusion, breathing heavily herself. "You improved exponentially between our first duel and the last, which clearly shows that you have extraordinary potential — dare I say, even more than your father ever did, and he was superb at transfiguration."

Whether she had intended it or not, the professor's compliment led to a deep discussion about Harry's parents — his father, in particular. Having no real memories of them to speak of, getting to hear so many unfiltered stories about young James and Lily Potter was enough by itself to make the entire week worthwhile. It was especially ironic that his sessions with McGonagall may never have happened in the first place, had it not been for Umbridge assigning him detentions.

As much as he had enjoyed his 'detentions', by the time Harry woke up on Friday morning he was grateful for the break. Not only had they be extremely gruelling, but they had also cut heavily into his free time. That meant no training with Daphne or his friends for the entire week, and even worse, little to no alone time with Astoria — although thankfully, she had been quite understanding about it all.

The Gryffindors trudged down to breakfast together, as they often did, discussing their plans for the upcoming weekend. Now that they made up nearly two-thirds of the team, the Weasleys would be spending quite a bit of time on the Quidditch pitch, preparing for the following week's matchup against Slytherin. It had been a surprise to nearly everyone when Ginny turned out to be the best candidate by far to replace Harry at the Seeker position. The lone exception to that was Hermione, who had already known that Ginny had, for years, been secretly flying her brothers' brooms, whenever they weren't around to see.

"You will be done in time, won't you?" Hermione asked again, as she buttered a slice of toast.

"I fink so," replied Ron, with a mouthful of eggs. Swallowing, he continued, "Angelina's gone a bit mad this week, but even so, I don't see her carrying on past dinner."

"Well, the entire team signed up to join us, so she'd better not," grumbled Harry. As much as he tried not to be, part of him was still slightly bitter about not being able to play. "There are a lot of people coming tomorrow, so we won't be able to wait for you."

Having to delay the first meeting of their defence club because of Harry's detentions had come with an unexpected benefit: with so many people having come around to believing him, recruiting more members had been positively easy. The real challenge had been finding a time that worked for everyone, but after several rounds of negotiation, the group had settled on Saturday after dinner.

"I'll remind her, but if she starts yelling, I'm sending her to you."

"And I'll send her to Hermione," replied Harry, letting a chuckle slip.

"How chivalrous of you," Hermione said sarcastically, as she unfurled that morning's edition of the Daily Prophet. Her eyes dropped down to read the headline, and her face turned white as a sheet. "No…" she gasped, just loud enough to attract everyone in the vicinity's attention.

"What is it?" Neville asked nervously.

Instead of replying, she spread the newspaper out on the table in front of them so everyone could see. Printed at the top of the page in enormous black letters was a headline that made Harry's blood run cold:

MASS BREAKOUT FROM AZKABAN!

MINISTER SUGGESTS BLACK RESPONSIBLE FOR FREEING INCARCERATED DEATH EATERS

Ron nearly choked as he read it, managing to spray pumpkin juice all over paper. The entire front page was filled with black-and-white photographs of the escaped Death Eaters, each of them captioned with the name and crimes of the wizard in question (or in one case, the witch in question).

Antonin Dolohov, read the caption below a wizard with a pale, twisted face and a sneer that would put even the worst in Slytherin House to shame, convicted of the brutal murders of Gideon and Fabian Prewett. Harry could understand why that would set Ron off, as he knew that Fabian and Gideon had been Mrs. Weasley's brothers.

Bellatrix Lestrange, said the line underneath a haughty-looking witch with wild, unkempt dark hair and heavily lidded eyes, convicted of the torture and permanent incapacitation of Frank and Alice Longbottom.

Harry glanced over at Neville, who looked like he was about to be sick. He could barely imagine what the boy was going through at the moment. While Harry had learned what happened to Neville's parents the year before, as far as he knew, Neville had never actually spoken to anyone about them.

Carefully reading through all the captions, Harry attempted to commit all ten faces to memory. New enemies had been introduced to the playing field, and he needed to be ready. One of his first orders of business would be to find out if any of the escapees had relatives in Hogwarts he needed to watch out for. He had just reached the bottom of the page when he felt two delicate arms encircling one of his.

"I can't believe it," rasped Astoria, leaning into his shoulder.

"I know," Harry replied bitterly. "I can't believe Fudge is blaming the breakout on Sirius!"

"No, not that," she replied, tears now pooling in her eyes. "That one there," she said just loud enough for Harry to hear, pointing at a thin man with light-coloured hair and a sharp nose, "is my mother's first cousin. He's been in Azkaban since before I was born, but I've heard stories — he's completely awful!"

Harry looked sharply down at the paper and re-read the caption.

Talford Travers, convicted for his role in the slaughter of the McKinnon family.

"What does this mean for you?" he asked urgently. "Will this put you in danger?"

"I — I'm not sure," she answered uneasily. "I have no idea how Mother will react to this…I need to talk to Daphne." Astoria quickly turned around, and spotting her sister at the far end of the Slytherin table, she let go of Harry and marched off to meet with her.

"What's it say?" Harry asked Hermione, who had begun reading the accompanying article.

"Nothing useful," she huffed. "Just Fudge making up excuses and attempting to spin the narrative."

"Wanker," Harry muttered under his breath.

He gazed around the Great Hall and was surprised to see that the breakout hadn't generated nearly the buzz he would have expected. Aside from a handful of older students, most everyone was carrying on as if it were a normal day. Malfoy was sporting a satisfied smirk, and for a moment, Harry could have sworn the ferret had even winked at him from across the Hall.

Notably absent from the Great Hall were Snape and Professor Dumbledore. The rest of the staff, however, were mostly engrossed in conversation, their serious expressions a good indicator of the topic. The lone exception was Professor Umbridge, who for once was keeping to herself at the far end of the table, her eyes firmly fixed on her porridge.

"What do you think's going to happen now?" asked Ron, to no one in particular.

Harry's eyes flitted back towards the Slytherin table to see Astoria and Daphne in the midst of what seemed to be an intense conversation.

"I'm not sure," he replied, "but tomorrow's meeting just became a lot more important."

oOoOoOo

Standing at the far end of the Room of Requirement, Harry, Ron, and Hermione looked on in amazement at the large collection of students gathered for the first meeting of their defence club. A few were standing, but most had found seats on one of the assorted chairs or cushions provided by the Room and were conversing with one another while they waited. As for the Room itself, it had taken on the shape of Harry's usual training setup, except that it had somehow doubled in size in order to accommodate the higher number of occupants.

"This is mad," Ron murmured to Harry. "Are you sure you can handle this many people? There's got to be fifty of them!"

"What do you think I have you two for?" Harry muttered back.

"Us?" replied Ron incredulously, glancing anxiously at Hermione. "You expect us to teach? How are we supposed to do that? We can't do what you do!"

"You're joking, right?" Harry deadpanned. "We've already been at it for a month and a half — you're way better than most of the people here." Ron relaxed slightly, but Harry could tell his friend was still unconvinced. "Don't worry, I'll do most of the work," he assured him. "All you'll have to do is walk around and give people tips, and maybe the occasional demonstration."

"If you say so," he shrugged, though Ron obviously wasn't thrilled with this latest development.

"Are you ready?" Hermione asked them nervously.

"As I'll ever be," responded Harry. "Why don't you lead us off, and I'll pick it up when it's time for the actual lesson."

"Shouldn't we do the charm first?"

Harry looked out thoughtfully over the assembled crowd. Most of the faces were familiar to him, even if he couldn't recall everyone's name. It was a little more difficult to tell, as they were all in their weekend attire, but around half of them were Gryffindors, with the balance being made up mostly of Ravenclaws, and only a half-dozen or so Hufflepuffs. Disappointingly, it seemed that Harry's interview hadn't entirely countered the distrustful sentiment coming from Cedric's old House.

Far less surprising was that he couldn't spot a single Slytherin. Daphne was the only one he would have considered inviting, but he didn't bother, knowing she wouldn't have agreed anyway. While Harry recognised the possibility that there were a few more decent Slytherins, he was reasonably certain that none of them would take the risk of joining their group.

"It's probably not a bad idea, but we should probably explain what we're doing first," he finally answered.

"Okay, here we go," said Hermione, more to herself than to Harry. Taking a few steps forward, she cleared her throat and called out in a loud voice, "Good evening, everyone. Thank you for coming."

It took a few seconds, but the room gradually fell silent as people finished up their conversations.

"So…" continued Hermione, suddenly sounding less confident now that she was faced with dozens of people looking up at her expectantly. "…erm…well, we're here because we thought people might like to learn proper Defence this year, instead of whatever rubbish Umbridge is 'teaching' us."

"Too right!" Fred called out, prompting several nods of agreement, along with a few chuckles.

"Right," said Hermione, sounding a little surer of herself. "Seeing as how you're all here, most of you must have worked out that Harry's been telling the truth…Lord Voldemort is back, and with nearly a dozen more escaped Death Eaters on the loose, things are probably going to get dangerous soon."

"Are you sure…like really sure he's back?" asked Justin Finch-Fletchley, almost fearfully.

"Definitely," said Harry, stepping up next to Hermione. "Believe me, no one wishes it weren't true more than me, but just so we're clear, I'm not here to answer questions about what happened that night. There isn't much I could say that wasn't printed in The Quibbler anyway," he added, giving Luna a little wave.

Harry's statement prompted some murmurs from the crowd, but no one challenged him on it. He glanced to the left and saw Astoria smiling up at him, surrounded on either side by her best friends.

"Look, I wouldn't be doing this if it weren't important," he continued solemnly. "Knowing even basic defence could literally mean the difference between life or death — for you and your families." The room quickly fell silent again. "It's fine if you're sceptical — just keep it to yourself," he added. "If nothing else, you can use this as an opportunity to prepare for your exams."

"Why should we listen to you, though?" questioned Cormac McLaggen, the sixth year who also happened to be Ron's least favourite Gryffindor. "Some of us already have our O.W.L.s, and I'm no slouch with a wand myself."

"Oh please, Harry would have you tied in knots before you could even draw your wand," groaned George.

"Show him, Harry," added Fred, which turned out to be a popular suggestion, based on others' vocal reactions.

"Maybe later," Harry chuckled, holding his hands up to settle everyone down again before fixing his gaze on McLaggen. "Nobody's forcing you to be here," he pointed out. "If you're not interested, then you're free to leave. For what it's worth, though, I already have my O.W.L. in Defence, too."

"Oh, so is that why you don't go to Umbridge's class anymore?" asked Lavender Brown.

"That's right," he confirmed.

"Harry got an 'O' without even revising first — how'd you do on yours, McLaggen?" retorted Ron, with no small amount of glee. The older boy grumbled in his seat but made no move to leave.

"Is it true you can cast a Patronus?" called out a redheaded Hufflepuff girl, whose name escaped him.

"I can," he confirmed, setting off a new round of murmurs. "We'll go over them at some point, but not right away. I've been told that the dementors joined Voldemort during the last war, so it's definitely a spell worth knowing, if you can manage it."

"Can you show us?" asked the blonde sitting next to the other girl — Hannah, if he wasn't mistaken.

Harry shrugged and pulled out his wand. He glanced over at Astoria again, and he allowed the memory of their first kiss to flood into him as he spoke the incantation.

"Expecto Patronum."

There was a brilliant flash of white light, and the enormous silver stag burst from Harry's wand and cantered about the room in search of a threat. There were several gasps heard among the crowd, along with a collection of 'oohs' and 'ahs', as the shining Patronus made its way back towards the front of the room, just before Harry dismissed it.

"That was wicked," said Michael Corner, a fifth-year Ravenclaw, who interestingly enough, was sitting rather close to Ginny on one of the sofas.

"Harry's Patronus has always been impressive, but I feel like we're getting off topic," interjected Hermione, reclaiming control of the conversation. "The point is, Harry is going to teach us whatever he thinks we need to know. For now, though, we need to figure out how often we're going to meet and come up with a good way to communicate without Umbridge getting suspicious."

She glanced over at Harry, who nodded in return.

"But first, there's something important we need to do," continued Hermione, taking a deep breath. "This group is technically illegal, thanks to Educational Decree number twenty-five. That's why I'm going to cast a spell that will make it impossible for you to discuss it with anyone who doesn't already know the secret."

Hermione paused to gauge the others' reaction, but most of the group just stared blankly back at her.

Speaking up again, Michael Corner asked, "You can actually do that?"

"I suppose we'll find out," Hermione muttered quietly to herself, before speaking up again. "The spell will be easier if we give the group an official name," she informed them all. "Does anyone have any suggestions?"

Hermione's question set of a flurry of discussion as everyone tried to come up with a name they all liked. The offered suggestions ranged from dull (Defence Club, Defence Association), to humorous (Anti-Umbridge Alliance, Ministry of Magic are Morons Group), to borderline militant (Hogwarts Revolutionary Force, People's Front of Hogwarts). A few people were even in favour of calling it Dumbledore's, or even Potter's Army, which Harry vehemently rejected.

"Look, it's got to be something vague — nothing that spells out what we're doing in here, and definitely nothing with anybody's name attached to it," said Harry, running his hand through his hair in frustration.

Eventually, Anthony Goldstein suggested calling themselves the Hogwarts Underground, apparently modelled after muggle resistance groups that popped up across Europe during the Second World War. Nobody seemed opposed to the mostly innocuous suggestion, and having already grown tired of the debate, Harry readily approved.

"Okay, I think we're finally ready," announced Hermione. "I'm going to need everyone to be completely quiet for a few minutes whilst I cast the spell. Once it's done, you're all going to feel confused for a moment, but it will pass as soon as Harry speaks the secret."

A few looks were exchanged amongst the group, but nobody said a word. Ron took a few steps back to make sure he wasn't in the way, and drawing a deep breath, Hermione took out her wand. Closing her eyes, she began quietly muttering under her breath as she waved her wand in intricate patterns in front of Harry. This went on for close to a minute before she opened her eyes, and pointing her wand directly at Harry's chest, she spoke the incantation aloud.

"Fidelio."

Everyone in the room immediately started looking around in confusion, indicating the spell had been a success. Harry was so engrossed in observing everyone's reactions that he momentarily forgot he still had a role to play.

"Go ahead, Harry," Hermione prompted him.

"Oh, right," he said, before calling out in a clear, ringing voice, "The members of the Hogwarts Underground meet in the Room of Requirement."

All at once, everyone remembered where they were and why they were there, prompting both bouts of laughter and looks of amazement from the group.

"How did you learn the Fidelius Charm?" asked Cho, who seemed both shocked and impressed.

"I worked on it for the better part of a month," Hermione admitted proudly. "Professor Flitwick helped too, even though I never told him why I wanted to learn it."

"Good job, Hermione," said Harry, placing one hand on her shoulder. "Right, so now that's done, we have enough time for a quick lesson before curfew. First, we need to see where everyone's at with the basics, so we'll start with disarming and shielding."

"Disarming? Really?" complained Zacharias Smith, who Harry recognised from the Hufflepuff Quidditch team. "After all that, you're just going to show us Expelliarmus?"

"It's called building a foundation, Smith," Harry replied irritably. "If you can't do a proper Disarming Charm, how do you expect to handle the more difficult spells?"

"Oh please, almost everyone here is in fifth or sixth year," replied Smith, making a sweeping gesture with his arm for emphasis. "I'm sure everyone here can do the Disarming Charm."

"All right, let's see yours, Smith, if you're so bloody talented," snapped Ron. The Hufflepuff hesitated, so Ron took out his wand. "Come on, then, disarm me — give me your best shot," he challenged him.

"Fine," said Smith, drawing his own wand. "Expelliarmus!"

Ron never even bothered moving as the spell lazily passed by him, several inches outside its target.

"I'd say there's room for improvement," Harry said flatly, prompting a few chuckles. "Ron, a demonstration, if you would?"

Before Smith even knew what was happening, Ron's spell had sped across the room and impacted his chest, separating the boy from his wand and knocking him off his feet for good measure.

"And that is why we're starting with the basics," declared Harry. "Some of what we do in here will be fun, but out there, it isn't a game — remember that," he added, taking care to look around the room and make brief eye contact with each and every one of them.

Satisfied that his point had been made, Harry flicked his wand, and the three remaining training dummies zoomed out from against the wall and spaced themselves equally across the floor.

"All right everyone, form up into three lines — one for each dummy. We're going to work on the Disarming Charm," he announced. "For those of you who don't know, the incantation is Expelliarmus, and the accepted wand movement involves a tight spiral directed at your target," he explained, as they all started to queue up. "For the first time through, you'll each get to attempt the spell three times, and Ron, Hermione, or myself will be there to give you some tips on how to improve. Any questions? Right, let's get started."

Harry gravitated over towards the line where most of the Ravenclaws had gathered. Terry Boot went first, followed by Lisa Turpin and Eddie Carmichael, and then Cho stepped up to try the spell.

"Thanks for doing this, Harry, this is really great," she told him.

"Sure, glad you decided to come."

"Oh, this is my friend, Marietta," said Cho, introducing him to the curly-haired girl beside her.

"Er — nice to meet you," said Harry.

"Hi," replied Marietta, though she didn't seem overly eager to engage in conversation.

"All right, well…did you want to try the spell?" he asked Cho, gesturing towards the dummy.

"Yes, of course," she replied quickly, sounding slightly abashed. She took out her wand and cast the spell, catching the dummy in the shoulder.

"Not bad," nodded Harry, trying to sound encouraging. "Try widening your stance just a bit — it may help keep your arm level while you're casting."

Cho took his advice, and both her second and third attempts were much more on-target. She then stood by while Marietta performed the spell with a look of disinterest, and then they both moved to the back of the line together. Next was Luna, who impressed Harry with her fluid movements and surprising accuracy, and then it was Astoria's turn.

"Well, here we are," Harry grinned as she approached.

"As promised," she smiled back at him.

"Have you had much practice with disarming?" he asked, being rather unsure about her level of experience.

"Not really," she admitted, sounding slightly nervous. "We learned the spell last year, but it's not something I've ever really worked on."

"It's no problem," Harry reassured her. "Why don't you just let me see what you can do, and we'll take it from there."

"Okay," she said, taking a step forward and holding out her wand.

Right away, Harry could tell she was going to have trouble. Her stance was rigid, with her shoulders square to the target and her feet set side-by-side. What was worse, Harry could actually feel the tension in her magic, leaving little doubt that Astoria was well out of her comfort zone.

"Expelliarmus!" she called out, but her wand produced nothing but a few red sparks.

Astoria turned back to look at Harry. "See? I told you I was rubbish at this," she said disappointedly.

"That's okay, we all have to start somewhere," he responded, moving to stand beside her. "Don't be too hard on yourself. Here, let's try this." Putting one hand on her right shoulder and the other on her waist, he gently guided her into a more natural duelling stance. "Standing like this will help, but more importantly, you need to relax," he murmured in her ear. "Your magic is hesitant, like it's so used to being bottled up that it's not sure what to do."

Astoria's eyes widened, and she actually forgot to breathe for a moment or two.

"The spell isn't very demanding; you can definitely handle it," he continued, moving his right hand from her shoulder to her wrist. "Ease your grip on your wand just a bit, then take a deep breath and feel for your magic. Can you do that?"

"Yes," she replied quietly, doing as he asked.

"Good." Harry let her go and took a step back to give her some room. "Now, just allow your magic to flow freely, and cast the spell."

After another deep breath, Astoria tried again — only this time, not only did she succeed in casting the spell, but she also managed to hit the target and relieve the dummy of its wand.

"Well done! That was much better," praised Harry as she turned around, revealing her beaming smile.

"Thank you! I actually have managed the spell before, but it was never that strong," she told him. "You're a really good teacher."

"I'm not sure I'd go that far, but thanks," he replied modestly.

Feeling much more confident, Astoria tried the spell a third time and easily replicated her previous success. The process was repeated with each remaining person in line (although not quite as hands-on), until everyone had their turn. Checking the time, Harry realised it was too close to curfew to start on another spell, so he asked them all to pair up and work on disarming one another.

It was definitely a lot more hectic than their usual sessions, which Harry supposed was to be expected, with close to fifty teenaged witches and wizards in close quarters, casting spells at one another. He used the time to walk around and offer advice, but more than once, he found himself simply standing back and watching.

It all felt very surreal. They weren't even two months in, and already, the year had been vastly different from anything Harry would have predicted when he boarded the Hogwarts Express in September. Indeed, some of the same people who had once thought him a liar were now coming to him to learn. Perhaps the Hogwarts Underground was actually what he needed; a common cause that could spawn new alliances, or even friendships. After all, was he not constantly being reminded that he didn't have to fight the war all by himself?

His only moment of concern was when he saw Astoria sitting down and taking a break while everyone else was paired up exchanging spells. He started to walk over and see what was the matter, but she saw him looking and waved him off, signalling that everything was fine. While he wasn't entirely convinced, he respected her wishes and let her be.

After about twenty minutes of practicing in pairs, Harry called for time.

"Good work, everyone," he shouted, waving for them to quiet down. "We didn't get around to shielding, so we'll start with that next time. There are too many people to work around everyone's schedules, but we'll try to find a time next week that works for most people."

"Let's hear it for Professor Potter and his lovely assistants," called Fred, setting off a round of mixed laughter and applause.

"All right, all right," said Harry, holding up his hands for quiet. "It's probably best if we don't all rush out of here at once, so I'm going to let you go in groups, once I'm sure it's clear."

With that, he pulled out the Marauder's Map and stood by the door. Umbridge was still in her office and Filch was down by the dungeons, so every few minutes, Harry let them go in groups of eight to ten until the room cleared out. Telling her friends she'd catch up, Astoria lingered behind with Harry and the others.

"I'd say that went rather well," Hermione said excitedly, once the final group had left for their respective common rooms.

"Bloody brilliant is what it was," added Ron. "Thanks for letting me get one in on Smith, by the way — I never did like that tosser."

"Me neither, but the point needed to be made either way," replied Harry.

"Yeah, well next time you need to make a point, make sure you use McLaggen."

"That's not why we're doing this, Ronald," scolded Hermione, causing him to hold his hands up in surrender.

"I know, I know — I'm just saying…"

"Great job with the Fidelius, by the way," interrupted Harry. "There's no way this would've happened without you learning the spell."

"It really was quite fascinating," said Hermione, obviously pleased with herself. "I've been curious about it ever since third year, so I'm glad I learned it."

"We should all be glad," Astoria chimed in. "I forgot to tell you," she added, turning towards Harry. "We figured out that our friend…well, former friend Ethan was the one who told Umbridge you were planning to start a Defence club. That's what prompted her to make that decree."

"I was afraid of that," he sighed. "How'd you find out for sure?"

"Just based on some of the things he said," she shrugged. "He did admit it though, after we confronted him. There was a big row in the common room, and all three of us are refusing to speak to him."

"Wait, who's this Ethan bloke?" asked Ron.

"Short and skinny, brown hair, definitely doesn't like me," replied Harry, listing off what little he knew about the boy.

"I know who you mean," said Neville, who had been oddly quiet for most of the day. "I always thought he was just jealous of Harry."

"Felicity said the same thing," Astoria replied bashfully. "I never saw him that way, but she thinks he's fancied me for a while — I just never noticed."

"Ouch," said Ron. "I'd almost feel sorry for the tosser, if he hadn't tried to sell us out."

Hermione lightly slapped Ron on the arm with the back of her hand.

"Oi, what'd I say?"

"No, it's fine. It doesn't matter anymore, anyway," replied Astoria, taking Harry's hand. "We should probably get going though, shouldn't we?"

Harry checked his watch. "Yeah, it's only twenty minutes to curfew. You guys go ahead," he said to the others, "I'm going to walk Astoria back to her common room."

"You don't have to do that," she said quietly, as the three Gryffindors said their goodbyes.

"I want to," he said, before joking, "unless you're trying to get rid of me."

Laughing, Astoria entwined her fingers with his and pulled him towards the door. Neither seemed to be in any particular hurry, but still, they set off along the quickest path back to Ravenclaw Tower. They walked in silence for a while, until Harry asked the question that had been on his mind for the past several minutes.

"I saw you had to sit down for a little while. Everything okay?"

Astoria sighed, and for a moment she didn't speak. "I have a…condition," she said eventually, still staring straight ahead. "It's usually not a problem, but I get exhausted easily if I use too much magic."

Harry turned his head to look at her. Daphne had mentioned something similar but refused to elaborate. He found himself becoming more and more curious about Astoria's mysterious condition, even though he knew he shouldn't pry.

"Is there anything I can do to help?"

"No…I wish there was," said Astoria wistfully. "I'm usually good at managing it; I think I just got caught up in all the excitement."

"Today was pretty fun," agreed Harry. "Aside from getting tired, did you enjoy yourself?"

"So much," she replied happily. "I think everyone liked the spell practice, but my favourite part was when you demonstrated your Patronus."

"Really?" he asked, genuinely curious. "Had you never seen one before?"

"No, actually, but that's not it…" she replied hesitantly. "I don't know if you saw, but it stopped right in front of me for a bit, right near the end."

"Sorry, I must've missed it."

"Well…it just stopped and stared at me for a moment," she said, her cheeks flushing slightly at the memory. "It was so beautiful…I felt like I could reach out and touch it, and I almost did." When Harry just continued to look at her, she went on, "When it got close to me…and I can't believe I'm telling you this…it felt like you."

"What do you mean?" he asked curiously.

"I don't know how else to describe it. It just felt…warm, and protective…almost like it was there just for me."

Harry turned his eyes forward again, though a smile quickly bloomed on his face. "Maybe that's because I was thinking about you when I cast it," he confessed.

"Wait, really?" said Astoria, stopping in her tracks.

"Of course," he grinned back at her, pulling her along with him.

Astoria clearly wasn't sure how to react, which Harry found quite amusing. He glanced over and saw that her cheeks were still flushed, and she was subtly worrying at her lower lip — an unconscious habit of hers that he found particularly bewitching.

"So…were you thinking of any memory in particular?" she asked finally, no longer able to contain herself.

Harry grinned. "Our first kiss," he replied, still looking ahead.

Astoria fought to hide her smile, but it was a losing battle. "I think about that night a lot, too," she admitted.

"Maybe we should have another date in the Room?" he suggested, just as they were reaching the entrance to the Ravenclaw common room.

"Absolutely," replied Astoria, pulling Harry to her and giving him a long, lingering kiss. "That will have to hold you over for now, though," she said as she pulled away.

"So…tomorrow then?" Harry asked hopefully.

"Maybe," she laughed. "Good night, Harry."

"Good night."