In Ron's imagination, the flames dancing in the common room fireplace grew just a bit stronger as he rolled his eyes upwards to glare at his older brother.

"Don't you remember?" Percy was saying.

"Of course I remember," snapped Ron. How could he ever forget?

The first crack shattered the jovial mood of the warm August night. Ron swerved suddenly in mid-air, almost crashing into Fred; the quaffle fell out of George's hands. All three turned to watch nervously through the lit window.

Percy was shouting menacingly, wand in hand. "I would NEVER!"

Isaac's reply was calm. "Come on, Percy. Don't tell me you haven't been thinking precisely the same thing."

Another loud crack, and Percy's bedroom window shattered; Ron had to duck to avoid a shard of broken glass. "YOU'RE SHAMELESS!" cried Percy. "You do not say that in this house."

Isaac chuckled. "I'm not the one who should be ashamed, Percy," he responded, the coolness in his voice making the summer night feel chilly. "All I did was say what you've been thinking, I bet for years."

Percy sputtered, then went silent for a horrible second, planning his final move. He couldn't exactly win in a straight-up duel with Isaac, but he had the advantage in resources. "Get out. I can't stand you. My mum will listen to me, and you'll be gone before breakfast."

Isaac's voice acquired a weary tone. "No, really, don't bring her into this. I'll be on my way."

"You kicked him out of the house," said Ron. "He was a bloody orphan, and just because he was interning at the Ministry—at the job you were rejected for—you found an excuse to kick him out."

"Ron, I was friends with Isaac for three years. He is a selfish, conniving, ungrateful trickster who just happens to gain the adoration of all the professors because he studies magic like a lunatic. I am forbidding you, as your Prefect and as your Elder Brother, from attending this meeting."

"You're just jealous that he didn't invite you," Ron jabbed back. "Jealous that you didn't think of this. You know, I bet it'd just kill you, wouldn't it, if he got Head Boy over you. Oh I'm Percy Weasley, the world's biggest git, and I can't even be top of my class after talking down to everyone for seven years."

"Ronald Bilus Weasley," Percy said with a cold stare. "This matter is not about me, it is about Isaac and what he's doing with this crazy group of his." The older boy's voice lowered, reaching almost a whisper. "The Slytherins are already calling it Wilkinson's Army."

"You're not—Come on, Percy, you know that's just Slytherin talk. It's just a dueling club. What would Isaac want with an army?"

Percy would've laughed, had he possessed a shred of a sense of humor. "Ron, Ron, Ron, there are some things in this world you have to learn from experience. I've learnt that Isaac Wilkinson is one of the most dangerous people you will ever meet. If I were you, I would be glad that my brother was thoughtful enough to warn me ahead of time."

One week later

Ron thought he finally understood why his mother had always told him to avoid stressful activities right after dinner. He was feeling a tad queasy at the moment.

"This is so mad," he whispered. "Absolutely confundingly mad."

"This is amazing," said Harry, paying no attention to his friend. "I can't believe Sirius actually said yes."

"Yeah, I'm starting to think he might be a bit mad too."

The day before, Harry's godfather travelled to Hogwarts and personally delivered to Harry a small, messily-wrapped package. Apparently, the great Sirius Black did not trust the Owl system; Ron wondered if he'd suffered any lasting psychological scars from his famous discovery a couple years back of the fabled Library of Ravenclaw, and his subsequent duel with the giant owl who guarded its secrets.

"Sirius might be mad," said Harry. "But he's a mad genius."

Ron sidestepped quickly to avoid an oncoming fourth-year. The hallways were annoyingly crowded, as many students were just now returning to their rooms from dinner.

"Can't we get rid of this thing?"

"Come on," urged Harry. "This is fun!"

A shock of blonde hair suddenly entered Ron's field of vision, and his frown turned into a devious smirk. "If we're doing this, I want to go over there."

"It's a really fine opportunity," Draco Malfoy was saying, not noticing the soft patter of feet coming from the empty space to his right. "Father says he wishes there was such a society of real wizards when he was at Hogwarts."

"I do wish," said his pug-faced companion that Ron identified as Pansy Parkinson, "that someone other than Isaac was leading it. It's so unnatural, don't you think? How is a muggleborn supposed to know, like, anything about dueling?"

"Muggles duel all the time. They have these metallic wands that shoot tiny exploding bulls. Though Father says it's a very, er, primitive sport for them."

"What the—you know that's not what I mean, Malfoy," pouted Pansy. "Just imagine a mudblood leading a bunch of witches and wizards in combat. Isn't the idea just, like, completely absurd? And to think some of the Slytherins are all excited about Wilkinson's Army—I thought you at least would have the sense to know that that would be, like, a complete disaster. The only thing I want to know is why Snape thinks so highly of him."

Malfoy took a quick look around and saw that the hallway was empty. "My dad was Prefect when Snape was a first-year," he whispered. "He says most people believed Snape was a half-blood, even though he never said anything about it. And—get this—half the house was convinced he was in love with a muggleborn girl."

Pansy shrieked. "You're lying to me, Malfoy. Professor Snape would never fall in love with anyone, and definitely not a muggleborn."

"Think about it, Pansy. McGonagall isn't particularly mean to us, but Snape never misses an opportunity to punish Gryffindors. He knows that if he ever starts looking soft on muggle-lovers, all the Slytherins who know his past will call for him to be sacked. Isaac is the only muggleborn he can help and get away with it."

Pansy grinned. "Maybe Snape's tough on Gryffindor because he thinks we're still at war."

Draco spun around to face Pansy. "Don't be an idiot."

"Oh, stop being so up-tight. There's no one here."

"There's no one here to what?" The loud, shrill voice of Professor McGonagall made all four first-years in the vicinity jump.

"Oh, uh, nothing, Professor. Draco and I were just, uh, talking about how, like, you aren't very mean to Slytherin and how, um, you would keep being nice to us even when there was no one else around?"

Ron and Harry had to work extra hard to choke back giggles. McGonagall looked intently at Pansy.

"As long as you show respect for your fellow classmates, Miss Parkinson. Which, I'm sorry to say, has not always been the case."

"I—what—did I just lose house points?"

Draco covered his forehead with his palm in disbelief. McGonagall now considered Pansy with a half-confused stare.

"If you wish, Miss Parkinson. Five points from Slytherin."

As Professor McGonagall resumed her brisk walk down the hallway, Ron pulled Harry into a secluded corridor. The pair took a quick look around, then pulled off the Invisibility Cloak.

"On second thought," said Ron with a wide grin, "this thing is amazing. Did you just see Malfoy facepalm just now? Amazing. What a bumbling idiot Pansy Parkinson is, eh?"

"Yeah," said Harry, looking equally excited. "I wonder what secrets we can uncover with this. Snape in love with a girl—that's an interesting image, isn't it."

Two minutes later, Harry and Ron strolled casually into the large, usually unoccupied classroom on the sixth floor. Rows of chairs were laid out near the far wall, while the front of the classroom was devoid of any furniture, save a lone desk. About two dozen students had found the room by this point, and one of them was wearing an icy stare.

"Really? You two are a piece of work," exclaimed Hermione. "Percy trapped me in the common room and cross-examined me for five minutes before he let me leave, and then only because I insisted I was sure you weren't coming!"

"Er…whoops," said Ron, too pleased with himself to be concerned. "Hey, how'd you get him to let you leave anyways?"

"Well I just told him that this was an excellent educational opportunity, that Professor Dumbledore gave Isaac permission to start it, and that if he thought he knew more about what school clubs should be allowed than Professor Dumbledore, then maybe he should drop out and start his own school of magic where nobody was actually given wands because that would be too much like a military." The words flew from her mouth like tiny bulls flying out of a machine gun. "And how did you two run Percy's common room blockade?"

"We got a seventh-year to disillusion us," Ron said quickly. Good thing we planned for this, he thought.

Hermione stared deeply into Ron's eyes for a second before shifting to an expression of curiosity. "I really want to try that, disillusionment. But it sounds really uncomfortable, doesn't it? Your skin heats way up as long as you're invisible."

"Yeah, well, that was kind of a pain, but you, er, get used to it, you know."

"Oh really? Because really when you get disillusioned it feels like cold water running down your head. You two really couldn't even look up the basic properties of a charm whose influence you were pretending to be under? And how on Earth did you actually get out? Presumably something bad enough that walking around the school under a disillusionment charm sounds tame by comparison."

"Why do you care about how we got here," Harry butted in. "Why is it so important for you to keep an eye on what everyone's doing?"

"Because when you two do something foolish and dangerous, it reflects badly upon all of us Gryffindors."

The entire room—now a colorful mosaic of nearly forty Gryffindors and Slytherins mixed with the occasional Hufflepuff or Ravenclaw—had by this point turned to watch the argument between The Harry Potter and his Ridiculously Smart First Year friend.

"Oh, so it's fine to talk back to a prefect and sneak out that way, but anything else that generates equivalent results is—"

"Silence, Mister Potter." The monotone drawl of Professor Snape cut Harry off mid-sentence.

Confused whispers of What's he doing here? floated around the room, but the Potions Master silenced these by clearing his throat. "For those of you incapable of recognizing me outside the confines of a room adorned with sheep intestines, I am Professor Snape. As I possess skills beyond those related to brewing potions, and since you are all choosing to participate in an activity fraught with danger, I will be attending these meetings so that these…activities do not get too far out of control. I have the authority to punish, by any means I deem appropriate, any action taken in this room that causes a dangerous or otherwise…undesirable situation to arise.

Ron raised his eyebrows and stole a quick glance at Harry, but Snape noticed immediately. "Mister Weasley, do you have a remark that you cannot bear to keep to yourself?"

"No, sir, I was just wondering how this would be different from potions class." A couple Gryffindors laughed weakly, then shut their mouths.

"Ah, yes, I'm glad you asked. In potions class, when you cause a cauldron to disintegrate due to incompetence, your grade suffers and you lose House points. When you sabotage another student's work, you receive a detention. In this club, if you cast a spell without permission, that spell will be used on you. And if you duel carelessly and recklessly, and create a dangerous environment for everyone, then you will be given the task of dueling me."

A few Slytherins snickered at this threat.

"And I would rather not duel you today, Mister Weasley," continued Snape, as he started pacing back and forth, "for it has already been decided by your friend"—he stopped to glare at Hermione—"that I should spend all of my free time reading her twenty-two inches on the magical properties of unshelled mucous-secreting gastropods."

Pansy Parkinson let out a half-chuckle before stopping and looking down to stare at the floor.

"It's—" Hermione was about to defend her verbosity but Snape cut her off.

"I wonder how many house points I should deduct for BANG!"

A sky blue bolt of light coming from the doorway exploded into golden dust halfway on its way towards Snape's back. The Potions Master turned and fired in one motion, wielding a red jet of light that whistled past Ron with a loud zing. A floating teakettle materialized in the middle of the room, absorbing Snape's curse and exploding, dousing water on everyone in the room.

The next thing Ron knew, he was falling on his bottom—the floor had been frozen and now gleamed with a thin sheet of ice. Snape slipped briefly, righted himself, and melted the ice below his feet with a burst of flame.

A dark figure now slid into the room, shooting off a flurry of spells that Snape blocked with a glowing white shield. The figure flicked his wrist, and the whole room became enveloped in a thick, dark fog. Snape looked around, seemingly lost, before his head disappeared into the mist.

The entire class breathed. Nearly half a minute passed.

Suddenly, the two combatants found each other again, unleashing a flurry of red and blue like Ron had never seen before. The duelists themselves were still shrouded in a haze, but the bright flashes of light revealed that they were on the move, circling each other.

"You're out of luck, Professor," said the intruder. "And out of room."

The red and blue flashes kept dancing around the middle of the room, meeting and annihilating each other.

"I don't know what you mean," replied Snape coolly.

Suddenly the red disappeared, and was replaced with a massive white screen. A loud thud shook the room, and a second later an even brighter red bolt shot out from a few feet above Ron, followed an instant later by the faint whoosh of a wand flying through the air. The fog cleared, revealing Professor Snape clutching two wands, standing on top of the desk that had somehow moved fifteen feet to sit right next to the doorway. Where the desk previously was, Isaac Wilkinson was standing wandless, a wry smile on his face.

The room applauded as though Filch had just been sacked. Everyone was in awe of the duel they had just witnessed.

"Professor Severus Snape, everyone," shouted Isaac as he motioned for Snape to take a bow; Snape ignored the suggestion entirely. He simply hopped down—or, more precisely, slowly hovered downwards—from the desk and sent it zooming back to its original location. Then, conjuring a beaten-up wooden chair, he sat down at the desk and began reading the Daily Prophet.

"I think I know just about everyone in this room," Isaac proclaimed once he had retrieved his wand and the applause had finally quieted down, "but for the sake of introductions, I am Isaac Wilkinson, Prefect of Slytherin and Junior Officer of the Auror Office. I've spent the last two summers learning the art of dueling from some of the best Aurors themselves. We'll talk about the duels you'll be fighting at the end of today's meeting. But first, I want to dissect the battle you just saw—or," he paused slightly and grinned, "couldn't see, as the case may be.

"Let's see, who should we pick on first…Hermione." Given that Hermione's reputation had already spread to most of the school, Ron was certain that this was not a random choice. "What stood out to you in that duel?"

Hermione had never looked happier. "Well, your main thesis seems to follow the dueling philosophy of Alastor Moody, who's famous for claiming that constant vigilance is the key to winning any magical battle. Professor Snape displayed knowledge of his surroundings both when he blocked your first hex and when he jumped onto the desk just when he was about to run into it. You made it hard for him to be aware of all his surroundings by summoning the fog and moving objects around while you were hidden. Without great attention to detail, Professor Snape would've fallen for your trap."

Isaac's wide grin returned. "I couldn't have said it better myself. Constant Vigilance! I would like everyone to close their eyes."

Slowly, as if they were worried Isaac would ram a desk into them while they weren't watching, everyone in the room followed.

"Raise your hand if you are standing under a chandelier."

Professor Snape whipped out his wand and applied at least five different silencing charms to the higher-year students who swore loudly at this instruction.

"Many a great wizard has been done in by failing to notice what lies above or below. Awareness of your surroundings is the key to any duel. But that wasn't the only thing we saw just now, was it, Miss Granger?"

"Well, when you used the tea kettle to block Professor Snape's spell, you introduced a new element to the environment that you knew about before he did. The best way to gain an advantage in a duel is to throw in a surprise that you've thought about ahead of time, especially if you can introduce it in a way that doesn't give up tempo."

"Astute observation. Yes, a good dueling strategy makes your opponent uncomfortable because he is reacting to changes that he does not expect. More often than not, your opponent will be used to casting hexes in the sterile environment of the classroom, and will be thrown off by chaos. And there was one more thing."

Hermione fell silent, as did the rest of the room.

"Professor Snape retained a perfect sense of where everything was in the room, even though I moved the desk after I created the fog. How?"

More silence. "Supersensory charm?" Hermione finally ventured.

"Echolocation," exclaimed Fred in the back. Ron gathered that Percy had given up on ever getting the twins to listen to him. Snape, however, had not reached that stage of enlightenment, and proceeded to dock Gryffindor ten points.

"I cast a spell to make the desk invisible to supersensory charms, and Professor Snape is, as far as I know, not an animagus. Any more guesses?"

Everyone in the room shook their heads no.


Hermione's hand shot up. "But legilimency requires eye contact, and the fog would have prevented him from seeing any more than a faint outline of you."

"Yes, but when you're Professor Snape, you don't need eye contact to perform legilimency. Once he knew where I was—because he could see the hexes I was firing—he was able enter into my thoughts and search through them easily enough to determine what I had done to the room."

A wave of nervous murmurs swept through the Gryffindor, Hufflepuff, and Ravenclaw sections. Was Professor Snape reading their minds too?

"No, I do not perform legilimency on students unless they have given me permission to do so, as Mister Wilkinson did before this duel. And no, I was not just listening to your thoughts, I was listening to your voices."

Now, Draco Malfoy's hand shot up. "So Isaac, are you saying that we're going to learn legilimency in this club? Because otherwise I think you've told us that we don't stand a chance in a real duel."

"The point I was trying to make, Malfoy, is that you can plan all you want, but in the end, the best predictor of who will win a duel is still raw magical ability. Dueling, like so many art forms, is a realm in which creativity and thoughtfulness only make greatness when paired with carefully honed skill. This year, I hope to impart onto you a little of how to excel in all aspects of dueling, from the strategic to the technical.

"Next week, we will begin practicing the all-important skill of casting spells in chaotic situations. You'll be working with an elementary hex by the name of collido. Make sure you can cast this spell for next week. Any questions?"

Heads shook silently.

"Okay. Er, club dismissed."

As the students slowly shuffled out of the classroom, Hermione approached Harry and Ron, not quite as peppy as she had been five minutes ago, but still apparently in a good mood. "You're right, Harry. It would've been a crime if you'd been prevented from seeing that. My gosh, aren't you so excited for next week? I need to get back and look up that hex, I'm sure I've seen it somewhere The Standard Book of Spells, Book One."

"Yeah, should be fun," said Harry. "Hey, listen, if you still want to know how me and Ron got here, I can show you; I owe you for all your help. You just can't tell anyone else."

Hermione just smiled and shook her head. "Don't be the kid who has to blurt out all the answers. I'll puzzle it out eventually." She turned around and spied Neville walking slowly out. "Hey, Neville! Wait up!"

Harry and Ron were the last to leave; they wanted to wait until it got less crowded before dawning Harry's cloak once again.

"Ten knuts says she figures it out by Christmas," said Ron.

Harry shook his head. "You think I'd bet against Hermione solving a puzzle? I'm not that dumb."

A Prefect's Duty is to maintain order at Hogwarts. Tolerance of subversive activities is weakness, and special treatment for anyone is corruption.

Percy Weasley rapped quickly on the thick oaken door and stared expectantly ahead.

"C-c-come in," said a nervous voice from inside.

Percy walked in and sat down in the straight-backed wooden chair in front of the defense teacher's desk. "You may already be aware, Professor, but if not, I think you deserve to be made aware of certain activities being carried out by Isaac Wilkinson and Professor Snape."

"Activities? Certainly the P-P-Prefect of Slytherin and his head of house are not doing anything n-n-nefarious?"

"Sir, Wilkinson has started a dueling club. Invitation only. Professor Snape is supervising the whole operation. I fear that both of them might be overstepping their bounds."

"Yes, I have heard a little about this society. Is there anything I should be c-c-concerned about?"

"It just seems out of place for a fifth-year student to be starting a dueling club with the Potions Master," Percy continued bluntly. "Such a club, if it deserves to exists at all, should really be under your supervision, not Professor Snape's. Besides, any student in the history of Hogwarts would be unprepared for the role Isaac has given himself. He's always taken on ridiculous challenges to try to prove his worth. I mean, he is the student who practically forced the Sorting Hat to put him in Slytherin even though he was a muggleborn."

Percy saw Quirrell twitch ever so slightly, and his voice became tinged with an unnatural, almost reptilian quality. "Wilkinson is a mudblood?"

For a second, Percy couldn't believe what he'd just heard. "Professor!"

Quirrell straightened up and became his normal, nervous self. "Oh, t-t-terribly sorry. Old S-S-Slytherin habits d-d-die hard, you might s-s-say."

"But I thought you were a Ravenclaw!"

"Oh, well, yes, I s-s-suppose I was." The defense teacher was paler than Percy had ever seen him, and seemed to wince with every syllable. "T-T-Thank you, Mister W-W-Westing, but I b-b-believe that this situation is un-d-d-der c-c-control."

Percy grinned meekly before sprinting out the door. He didn't stop until he'd gone three floors up.

What just happened? Was Quirrell going insane? Had the former Muggle Studies professor suddenly become blood purist?

And how, if Quirrell didn't even know his name, was Percy ever going to get a good recommendation letter for a job at the Ministry?