After a single step into Dumbledore's forbidden chamber, Harry shrieked and jumped back and collided with Rainbow Dash, sending the two of them down in a heap.

Rainbow Dash picked herself up and resumed standing in front of the door and glared at Harry. "Hey, watch it!"

But Harry's attention was occupied by the gigantic three-headed dog which had lunged forward, only to be stopped meters from Harry by the chains upon its three collars.

"That - that - that - " Harry said.

"Yes," Professor Quirrell said from a ways behind him, "that is indeed the usual occupant of that chamber, which is off-limits to all students, especially first-years."

"What's the matter, haven't you ever seen a Cerberus before?" Fluttershy whispered, sweetly.

"That's not safe even by wizard standards!" Within the chamber, the enormous black beast gave a multi-voiced bellow, flecks of white saliva flying from three fanged mouths.

Professor Quirrell sighed. "It is enchanted not to eat students, just spit them back out through the door. Now, boy, how would you recommend that we deal with this dangerous creature?"

"Uh," Harry stuttered, trying to think over the continued roaring of the chamber's guardian. "Uh. If it's like the Cerberus from the Muggle legend of Orpheus and Eurydice, then we have to sing it to sleep so we can pass..." Harry trailed off as the Professor rolled his eyes. "Avada Kedavra. I'm supposed to say Avada Kedavra, aren't I?"

Quirrell grinned, sardonically. "If I am to die today, at least I can rest easy knowing that I have finally taught you something worthwhile." His eyes trailed over to the collection of vibrantly-colored witches, "But as it so happens, you are correct in this matter. I suspect that were any harm to come to the creature, the Headmaster would be immediately alerted," he lied.

Fluttershy glared at him. "Harm? Why would you want to harm him?" She strode confidently over to the creature, who emitted a low, rumbling growl.

"Gee, I wonder why," Harry muttered.

"Aww, look at you, little guy. You're just a cranky little puppy, aren't you? Wouldn't it be nice to just take a little cuddly, cozy nap?" The beast cocked its head and then lolled one of its tongues lazily as Fluttershy began scratching it underneath a chin.

"Uhh, maybe while it's preoccupied with Fluttershy, we should just go ahead and scamper right on through that trapdoor," Applejack suggested, clearly eager to move past the room. She tiptoed closer, and the dog began to growl with renewed vigor.

"No, no, Applejack. Harry's right. We just need to sing him a little lullaby," Fluttershy cooed.

"Well, if there's one thing we're really good at, it's launching into curiously well-prepared musical numbers at a moment's notice!" Pinkie Pie gushed as she wielded a pair of drumsticks which Harry had not noticed her removing from her pouch.

And at that, the six launched into a curiously well-prepared musical number.

Harry's peculiar sense of foreboding seemed to flare, despite the jaunty song they were singing about 'hope shining eternal', or something like that. Notes of confusions danced in his mind as he saw... the Professor tapping his toe? In time with the music?

But what he saw next caused the notes to fold in on themselves. They became a fugue, an endlessly rising canon. No longer were they notes of confusion. This was a symphony of confusion.

The Professor was actually singing along with the song.

What in the name of Merlin's sweating, tangled beard was happening?

They reached the crescendo of the song, and each singer repeated the final line, "And the future is always bright... when you're here with me!"

Each singer, including the Professor. And now, apparently, it was Harry's turn.

Harry was decidedly not a good singer. And he definitely was not used to performing in front of an audience, even if it were a small one.

The music ground to an abrupt halt as everyone watched Harry expectantly, even the Cerberus, who began growling menacingly. It took a step forward towards Harry, which was enough to prompt him to overcome his stage fright.

"And the future is always bright... when you're here with me..." he mumbled, atonally.

The music resumed as quickly as it stopped, and the dog began to bob its head rhythmically in time with the waning refrains of the electric guitars. Harry did not have time to even process or question from where they procured their instruments, much less an electrical power source in Hogwarts. He merely stared, open-mouthed, as its head bobbed slower and slower until it finally sagged off to sleep.

"What the bloody hell was that?!" Harry shouted, but the troupe had already packed away the instruments and were heading down the trap door.

"Better hurry up, slowpoke! Before the big guy wakes up!" Rainbow Dash shouted.

Beneath the trapdoor was a gigantic plant, something like an enormous dieffenbachia with wide leaves emerging from the central stem like a spiral staircase, but darker-colored than a normal dieffenbachia, with tendril-like vines emerging from the central stem and hanging down. The base spread out wide with bigger leaves and tendrils, as though promising to cushion anyone's fall. Beneath was another stone chamber like the first, with the same nooks like false arched windows, emitting the same grey-blue light.

"The obvious thought is to fly down on the broomstick in my pouch, or toss something heavy to see if those tendrils are traps," Harry said, peering down. "But I'm guessing you'll say that we just walk down the leaves." They certainly looked like they were meant to be a spiral staircase.

"After you," said Professor Quirrell.

Harry carefully put a foot down on a leaf and found that it indeed supported his weight. Then Harry took a last look around the room before departing, to see if there was anything worth noticing.

"Harry, you might want to watch out. That plant in the middle there looks an awful lot like a Tartarus Vine." Applejack spoke slowly.

"You mean like the stuff Goldie Delicious drinks?" Pinkie Pie chimed in.

"Naw, that's Tartan Wine. Tartarus Vine, it's a tricky little plant that'll wrap its tendrils around you and drag you down so you can't move. The more you struggle, the tighter it'll wrap ya up. But there's a little rhyme they taught us, 'Tartarus Vine, Tartarus Vine, it's deadly fun, but will sulk in the sun!'"

Rainbow Dash scoffed. "How tough could one little plant be?" And she quickly bound down the verdant staircase. The spiraling leaves of the gigantic dieffenbachia felt like forest loam beneath her shoes, not as unyielding as concrete, but supporting her weight. Harry kept a wary eye on the tendrils, but they remained passive.

When she reached the bottom of the leafy spiral staircase, the tendrils suddenly whipped out and grasped Rainbow Dash's arms and legs. She let out a clipped cry and struggled mightily against them. Applejack folded her arms and rolled her eyes, but Harry looked panicked. Without really thinking, he trampled down the staircase and dived straight into the tendrils, wrapping her in a tight embrace.

"Listen, Applejack said the more you struggle, the harder it will squeeze you. Just be calm!" he shouted.

"How am I supposed to be calm with you shouting at me?!" she shouted back.

He rolled his eyes, and after a brief struggle, Harry allowed himself to go limp. The plant relinquished its grip, and Harry slid to the ground with a thud. Rainbow Dash watched, somewhat embarrassed, and stopped her own movement, quickly joining Harry on the ground.

"Interesting," said Professor Quirrell, as he walked down from above, not touching any of the plant's leaves or tendrils. "I notice that you seem to have no trouble losing to a plant.

"Now, of course, had you not charged headlong into danger in a somewhat foolish fashion, I could have proposed a much simpler solution to the problem that would have been far less embarrassing for the both of you," he leveled his wand and announced, "Lumos Maxima!"

The plant shrieked away from the blinding light, whipping and flailing in all directions, impotent to try to apprehend any potential victims. The rest of the group quickly descended the staircase and reached the bottom where Harry and Rainbow Dash were staring steadfastly and self-consciously at the floor.

The next chamber was smaller in diameter, with a higher ceiling. The light shining out of the arched alcoves was white, instead of blue.

Around them whizzed hundreds of winged keys, beating frantically through the air. After watching for a few seconds, it became clear that only a single key was the golden color of a Snitch - though it was moving slower than a Snitch in a real Quidditch game.

On the other end of the room was a door containing a large, prominent keyhole.

Against the left wall leaned a broomstick, the school's workhorse Cleansweep Seven.

"Professor," Harry said, staring up at the clouds and flocks of whizzing keys, "you said you would answer my questions. What exactly is all this about? If you think you've secured a door so that it won't open without a key, you keep the key in a safe place and only give a copy to authorized entrants. You don't give the key wings and then leave a broomstick propped against the wall. So what the heck are we doing in here and what is going on? It's an obvious guess that the magic mirror is the only real factor guarding the Stone, but why the rest of this - and why encourage first-years to come here?"

"I am truly not sure," said the Defense Professor. He had entered the room and taken up station well to Harry's right, maintaining the distance between them. "Dumbledore's way is to do a dozen things which seem mad, and then only eight of them, or perhaps nine, conceal an inner meaning. My guess is that Dumbledore set up this circuitous maze of traps as a means to entrap Lord Voldemort and that Dumbledore intends to make it seem like Voldemort is invited to send a student as his proxy. Precisely so that Lord Voldemort, as Dumbledore conceives of him, is less tempted to think himself clever by doing so. Imagine Dumbledore first considering the issue of how to ward the Stone. Imagine Dumbledore considering whether to set true dangers to guard the Mirror. Imagine him imagining some young student blundering through those dangers at Voldemort's behest. I think that is what Dumbledore is trying to avoid, by making it seem as though that strategy is invited, and so not cunning."

Harry turned away, looking at the door on the opposite side of the room. "My guess is that the intended solution for first-years is to ignore the broomstick and use Wingardium Leviosa to grab the key since this isn't a Quidditch game and there are no rules forbidding that."

"Yeah, well are there any rules forbidding this?" Rainbow Dash shouted as she grabbed the broomstick and shot off into the air after the erstwhile key.

"Of course she'd do that." Applejack drawled, smiling despite her vague annoyance.

Harry turned to the Professor, eyes rolling. "Don't you have some absurdly overpowered spell you could unleash on this one?"

There was a brief silence but for the whizzing of keys and Rainbow Dash deftly darting back and forth in the air. That silence was punctuated by occasional gasps of joy from Pinkie Pie, who was thoroughly enjoying the proceedings.

Harry took several steps away from Professor Quirrell. "I probably shouldn't have said that, should I?"

"Oh, no," Professor Quirrell said. "I think that is a quite reasonable thing to say to the most powerful wizard you know when he is standing not a dozen paces from you." He put his wand back into the sleeve of his other hand and smiled placidly. "As it so happens, I'm aware of several rituals of ill-repute that would demolish this door along with whatever lies behind it. But all things considered, I think it safer to simply perform the tasks as intended."

As if on command, Rainbow Dash issued a loud "Whoop!" and shouted, "Got it!" She deftly floated down to the ground, key triumphantly in hand, and made her way swiftly to the door. She looked backward expectantly as she unlocked it and moved on to the next chamber.

Harry stepped over the threshold of the heavy door and gazed at a chessboard of magnificent, wizard-sized chess-pieces. The alternating tiles of black and white marble on the floor started five meters after the doorway, and extended from wall to wall, but stopped five meters short of the next door on the opposite side of the room. The ceiling was significantly higher than any of the statues should have been able to reach.

"I would guess," Harry said, "that the intended solution is to fly over the statues using the broomstick from the previous room since it wasn't actually needed to get the key?"

Rainbow Dash held her fists on her hips, "Um, excuse me, but who actually got the key for you?"

The Professor looked up and spoke, eyes never returning to Harry. "I suppose she could try that. But what of the rest of you?"

Harry nodded. "And I assume that if we try to simply cross the board, these pieces would somehow forcibly prevent us from doing so?"

"Quite right."

"Pawn to D4!" Pinkie Pie interrupted, who had clambered atop the bishop next to the queen, causing the massive pawn to dutifully scoot two squares forward.

The other witches watched Pinkie, interested, but only Harry was a tiny bit skeptical. He turned to Rarity, who was closest to him. "I'm assuming she's a prodigy at chess, the same way she seems to be a prodigy at everything else?"

Rarity shrugged. "I suppose we'll see, won't we? As for me, I just can't get over the tacky aesthetic. You have all the options in the world available to you, and someone decided to go with... Baroque," she spat with a shudder on the final word.

Their conversation was cut short by the grinding sound of the black pawn in front of the king's bishop moved ahead two squares. It was one thing to watch a chess game from above, even Wizard's Chess, played out with pieces no larger than a finger. But seeing pieces twice his size carved of what appeared to be pure stone suddenly seemed to be much more intimidating.

Pinkie Pie slapped the crown of the bishop and shouted with maniacal glee: "To G5!" and with that, her bishop slid immediately to the right of the newly moved black pawn.

"Uhh, I don't know a TON about chess, but that seems to leave you a bit... vulnerable."

"HA! I eat danger for breakfast!" Pinkie Pie shouted in a sort of reverie.

"Hey, that sounds like something I would say. Stop stealing my lines!" Rainbow Dash protested.

As if to answer Harry's perceived threat, the pawn in front of the king side's rook moved forward a square, putting Pinkie in imminent danger of being captured.

"But maybe I'll save this danger for lunch," Pinkie backtracked. "Retreat! To G4!" and she moved diagonally backward one square.

"See, now you've lost tempo," Harry chastised, as the pawn in front of the king's knight moved forward two squares, once again putting her in danger of capture.

"Brave Dame Pinkie ran away, bravely ran away, away! When danger reared its ugly head, she bravely turned her tail and fled, brave, brave, brave, brave Dame Pinkie!" she sang. "To D3!"

And she scooted backward and to the right, apparently safe from imminent danger. But Harry was quite concerned by this point; she had given up two turns of board development. He leaned in toward the Professor, "What happens if she loses?"

He shrugged. "I suppose she would be knocked unconscious and the hospital wing would be alerted. But you should pay closer attention: even our pink-haired friend seems to know when it is appropriate to yield, to lose." He inclined his head as the first black pawn scooted ahead to F4, putting her in danger once again.

"She was not in the least bit scared to be mashed into a pulp. Or to have her eyes gouged out, and her elbows broken! To have her kneecaps split and her body burned away, and her limbs all hacked and mangled, brave Dame Pinkie! Pawn to E3!" Rather than move out of danger, she sent her queen's pawn ahead two places.

"WHAT ARE YOU DOING?!" Harry shouted.

"She's safe, boy, now do be quiet. This game is fascinating." The Professor hushed him sternly. "Observe: were the pawn to take the bishop, the queen would be free to check the king. And now..."

The black pawn on the farthest right of the board moved forward one space, cutting off the angle of attack from the queen, who would now be claimed by the rook were she to move to that position.

"Join me, fellow bishop! To D3!" And the king's bishop moved up, two squares in front of the white queen.

The black rook moved ahead two places, and Pinkie began to cackle maniacally. "Queen to H5! Toro, toro, toro!"

The Professor and Harry both watched as the Queen suddenly sprang into lifelike action, the liquid form of her stone moving as sleekly as a human being. She pulled a pair of daggers from the folds of her robes and eviscerated the black pawn who stood in her way. Brilliant red gems sprayed forth from the wound, prompting Rarity to shout with joy.

"What perfect specimens! Hand me that broom!" She took the broom from Rainbow Dash and delicately mounted the broomstick, flying awkwardly over to the ever-growing piled of glittering rubies that were leaking from the now-deceased pawn. But she barely had to swoop down to grab a handful as the black rook that was now directly in front of the white queen pulled an ax from behind its back and unceremoniously beheaded her.

Pinkie continued to cackle as red rubies shot violently into the air from the stump that once contained the white queen's stone head, splattering in several directions. The Professor was chuckling, and Harry first assumed it was due to the sight of several rubies pelting Rarity and almost causing her to fall off her broom. But he continued to smile dryly, even as Rarity escaped to safety.

Pinkie's laugh became darker and more ominous, and she held her fists in the air and looked up to the sky. Then, she stopped abruptly and looked toward the Professor. "What do you think of my 'evil villain' laugh?"

He bowed slightly to her, "Appropriately over the top. A masterful game, if I do say so myself."

"Thanks! Bishop to G6!"

Harry didn't even register that it was a checkmate until the black king dropped the sword from its hand, and toppled over. Then, like dominos, the remaining black pieces toppled over one by one, clearing the way to the next chamber.

Pinkie casually leaped from the bishop as the Professor continued his praise, "An excellent turnabout, the Dutch Defense into Hopton Attack..."

"Is that what that was?" Pinkie asked, sincerely.

"So... how long have you played chess for?" Harry asked.

"Oh, this was my second game! So fun! You first!" Pinkie was already bouncing ethereally off towards Harry and gestured to the next chamber, prompting a cock of the Professor's eyebrow.

"Yeah... that's Pinkie Pie, for you."

The Professor nodded. "She could prove quite useful, hm?"

"She already has," Harry said as he strode towards the door.

Half a second later, Harry slammed the door and leaped back.

It took Harry several seconds to master his breathing and master himself. From behind the door came continued loud bellows, and great slams as of a rock club pounding the floor.

"I suppose," Harry said, "that since Dumbledore would hardly put a real mountain troll in there, the next challenge is an illusion of my worst memories. Like a Dementor, with the memory projected into the outside world. Very amusing."

Professor Quirrell advanced himself toward the door, and Harry stepped well aside. Professor Quirrell swung open the door and looked in. "Hm," Professor Quirrell said. "Just the troll, as you say? Ah, well. I had hoped to learn something about you more interesting than that. What lies within is a Kokorhekkus, also known as the common boggart."

"A boggart? What does that - no, I suppose I know what it does."

"A boggart," Professor Quirrell said, and now his voice was again that of a Hogwarts Professor lecturing, "gravitates to dark enclosures that are rarely opened, such as a neglected cupboard in the attic. It seeks to be left alone, and it will manifest in whatever form it thinks will scare you away."

"Scare me away?" Harry said. "I killed the troll."

"You leaped backward out of the room without thinking. A boggart seeks out the instinctive flinch, not the reasoned threat. Else it would have selected something more believable. In any case, my standard counter-Charm for a boggart is, of course, one of the aforementioned absurdly overpowered spells, the name of which I will not utter here. But a less horrific counter-measure is simply laughter. I suggest we find someone whose fear takes a slightly less menacing form so that we can more easily summon up the proper state of mind."

Without a beat, five of the witches said in unison, "Rarity."

Her eyes went wide. "No," and she took a step back. "Please, don't make me. I've seen too many horrors! Don't make me do it!" she cried dramatically, almost hyperventilating while fanning herself.

Rainbow Dash and Applejack could barely stifle a giggle. "Go on, Rarity!"

Harry was nonplussed. He didn't doubt when she said she had seen horrors, and he wondered why the others were being so cavalier.

"Fine! If I must. I do what I must, for my friends," she took a deep, steadying breath, marched herself towards the door, flung it open, and proceeded to shriek. She took several steps backward, panting. Harry could briefly see the outline of a mirror beyond the doorstep.

"Well, what was it, Rare?" Applejack asked.

"She... she... she was wearing purple socks... with a BURGUNDY DRESS!" Rarity collapsed into a sobbing heap.

"A burgundy what, now?" Applejack moved a bit closer to the door.

Rarity looked up from the ground, vaguely annoyed that no one was as horrified as she. "Purple and burgundy, darlings! The same color family!" and she shrieked again.

Applejack could now fully see the reflection beyond the door, and could no longer stifle her giggle. She began to laugh in full force. The others moved closer as well and joined Applejack in her laughter as they observed a reflection of Rarity dressed in the most garish dress of an almost-eggplant hue, combined with a hideous pair of striped, neon purple socks. To top it all off, on top of her head was a hat crafted of pure absurdity, with a stuffed vulture perched on top. As the laughter grew louder, the mirror developed a thin, spiderweb matrix of cracks across its surface.

"The color combination is truly atrocious, I agree." The Professor remarked dryly, causing Harry to also giggle. This appeared to be the final straw for the mirror-Boggart as it shattered into countless thousands of pieces onto the floor, all of which sprouted tiny feet and retreated into an unseen corner with a single squeak, and then nothing.

They advanced into the boggart's former room, Professor Quirrell going first this time. With both the troll and the mirror gone, the room was just another huge chamber lit by sconces of cold blue light.

Professor Quirrell's gaze seemed distant, thoughtful. He crossed the room without waiting for Harry, and swung open the door on the opposite wall of his own accord.

Harry followed after, and not closely.

The next chamber contained a cauldron, a rack of bottled ingredients, chopping boards, stirring sticks, and the other apparatus of Potions. The light coming from the arched alcoves was white instead of blue, presumably because color vision was important to Potions-brewing. Professor Quirrell was already standing next to the brewing apparatus, scrutinizing a long parchment he had picked up. The door to the next chamber was guarded by a curtain of purple fire which looked quite threatening.

Harry's suspension of disbelief had already checked out on vacation at this point, so he didn't say anything about how real-world security systems had the goal of distinguishing authorized from unauthorized personnel, which meant issuing challenges that behaved differently around people who were or weren't supposed to be there. For example, a good security challenge would be testing whether the entrant knew a lock combination that only authorized people had been told, and a bad security challenge would be testing whether the entrant could brew a potion according to written instructions that had been helpfully included.

Professor Quirrell tossed the parchment toward Harry, and it fluttered to the ground between them. "What do you make of this?" said Professor Quirrell, who then stepped back so that Harry could come forward and pick up the parchment.

"Nope," Harry said after skimming the parchment. "Testing whether the entrant can solve a ridiculously straightforward logic puzzle about the order of the ingredients is still not a challenge that behaves differently for authorized and unauthorized personnel. It doesn't matter if you use a more interesting logic puzzle about three idols or a line of people wearing colored hats, you're still completely missing the point."

"Look at the other side," said Professor Quirrell.

Harry turned over the two-foot parchment.

On the other side, written in tiny letters, was the longest list of brewing instructions Harry had ever seen. "What on Earth-"

"A potion of effulgence, to quench the purple fire," Professor Quirrell said.

"It is made by adding the same ingredients, over and over again, in slightly different ways. Imagine some eager young group of first-years, passing all the other chambers, thinking they are just about to reach the magic mirror, and then encountering this task. This room is the handiwork of the Potions Master indeed," Professor Quirrell said, once more looking thoughtful. "Snape is not a bystander in this game, not quite. He lacks Dumbledore's intelligence, but possesses the killing intent that Dumbledore never had."

"Well, whatever's going on here, it doesn't actually keep out children," Harry observed. "Lots of first-years made it through. And if you can somehow keep out everyone except children, then that, from Dumbledore's perspective, forces Lord Voldemort to possess a child to enter. I don't see the point, given their goals."

"Indeed," Professor Quirrell said, rubbing the bridge of his nose. "But see, boy, this room lacks the triggers and tripsigns that are upon the others. There are no subtle wards to be defeated. It is as if Lord Voldemort is invited to bypass the Potion and simply enter - but Snape knows that Lord Voldemort will perceive this. If in fact there was a trap laid for anyone who did not brew the potion, then it would be wiser to lay wards, and give no sign that this room was different from the others."

Harry listened, frowning in concentration. "So... the only point of leaving off the detection webs is to make someone not bulldoze this room."

"I expect Snape expects Voldemort to deduce that as well," the Defense Professor said. "And past that point I cannot predict at what level he thinks an intruder will play. I am patient, and I have given myself plenty of time for this endeavor. But Snape knows Lord Voldemort. He has sometimes seen Lord Voldemort shriek in frustration, and act on impulses that appear counterproductive. Consider this matter from Snape's perspective: it is the Potions Master of Hogwarts telling Lord Voldemort to be patient and follow instructions if he wants to enter, as though Lord Voldemort were a mere schoolboy..."

"So what then?" Harry asked.

"We do what Lord Voldemort would not: we follow the instructions to the letter."

And with that, Harry began to brew.