To save everyone from the trouble of having to watch out for side-fics that are canon to the Danse Macabre world, I will be adding each fic as a chapter to this one.

I will name each chapter with hopefully enough information for those who may only be interested in some and not others. Each chapter will also have its own summary, and warnings if they're needed.

Now, onto the chapter.

Summary and warnings for this chapter (i.e. important author ramblings):

The title (and tags) is self-explanatory. Someone said they'd like to know what happened when Quirrell went down the Forbidden Corridor, so here we are. It does not start well. It does not end well.

I took especially long for this one because I initially meant for it to be humorous and light-hearted but it isn't. It's darker and heavier and kinda terrible actually. As I have zero experience writing this kind of thing, the more I wrote and read, the more averse to it I became, and I ended up taking several breaks in between trying to fix it. Now I realise that from the moment I decided to write it partially from Quirrell's POV, it was never going to be light. Both my beta reader (Miso_sleepy) and I feel bad for the guy now...

TLDR? Read at your own risk.

This is not my usual kind of writing. Quirrell has A Very Bad Day, after many many bad days, until he finally dies. Quirrell's health, both mental and physical are shit here. If that makes you uncomfortable, maybe give this one a pass.

My beta reader says it's good, despite my inexperience, so I'll leave it to you guys to judge for yourselves. I hope you'll enjoy it more than I do.

Chapter One: A Series of Unfortunate Events (feat. Quirrell)

"One to leave and one to stay and all to dance the Macabray." — The Graveyard Book by Neil Gaiman

Ever since the previous visit—a disastrous encounter that started and ended with a huge snarling snapping three-headed dog—Quirrell had made better preparations, which included, but was not limited to, an enchanted harp which would hopefully be enough to deal with the damn mutt, if the half-giant was to be believed.

He couldn't afford to fail. Failure meant death. He had no options out, not since he foolishly allowed the Dark Lord to possess him.

Foolishness.

He wanted to serve him, he did, still does—though his willingness on that front has been wavering recently—but he didn't want... this.

He tried not to think about it too much. He tried not to think about most things that weren't the Stone. The Stone that will finally allow the Dark Lord to occupy a body that wasn't his.

So, Quirrell brought an enchanted harp with him and stood in front of the door. Behind the door was a Cerberus. He could still remember, feel the terror, the pain, of—he never wanted to see a dog ever again. But he had to, because sharing the same body with the Dark Lord was worse.

It was an ache in his bones, like a fever under his skin, an infection in his blood. Magic that pulsed wrong wrong wrong and sometimes he really just wanted to bash his head against something hard and solid so that it would all just stop—because sleep didn't help. Sleep wouldn't come. He was too tired, but his mind was too loud—he barely understood it, sibilant hissing and harsh unintelligible whispers that scraped across his nerves and—he could barely focus—

Focus.

Three taps with his wand and magic that burned poisonous—his own magic that he was now allergic to—and the harp was playing.

Focus.

The harp was playing and he entered the first room. Thankfully, there was only a short moment—fierce eyes and large sharp teeth gnashing and darkness—before the dog slumped over and dropped into deep slumber.

One down. Six more to go.

Focus.

There was a trap door. He lifted it, ignoring how his arm trembled from the mere effort—and dropped down.

There was hardly any warning, just a moment of prickly warmth, before it escalated within a second to searing pain pain pain—

—Make it STOP—

Focus.

A list of spells spilled, faltering from his chapped lips, accompanied by a nauseating sense of vertigo and everything was suddenly cold and wet and it still burned but that was... No, it wasn't okay. None of this was okay. He could be anywhere but here. He could be—

Focus.

He was lying gasping in a twitching mess of—some sort of plant matter, he didn't really care—and then he was unceremoniously dropped into the room below. Dimly, he registered the dull feeling of hitting the floor, but it was overshadowed by everything else that he dearly wished he wasn't feeling—what in Rowena's raving raptors was that?—

Focus.

Next room was... Filius's. Whatever it was, he didn't think—he hoped—it wasn't any worse than whatever hell-plant Pomona had raised.

Quirrell looked down at himself—his vision swam—and shaking his head made it worse—but—okay, he wasn't intact. Half his robes had been burned off and he was certain he would be bleeding if the fire hadn't cauterised everything because there were parts where flesh was conspicuously missing. But his limbs were all there. Was his turban still on? He couldn't be sure.

The Dark Lord was silent. Well, not silent—there was a faint quivering keening noise—feeling—somewhere but silent enough. Small mercies.

The next room had keys. All he needed to do was to retrieve the right key to unlock the door. Simple. He could do this.

He couldn't do it.

The Dark Lord was a whimpering furious creature in his head and his magic wasn't cooperating and he couldn't fly without feeling like he was going to lose his breakfast lunch and dinner all at once and he couldn't even tell which key was the right one—

Where was it?!

He gave up. He didn't need a key. He just needed to—he felt sick just thinking about it—but he was running out of time. Who knew how long the Headmaster would be delayed before that senile old goat would realise something was wrong and come and ruin everything and the whole year he spent all this would be wasted and he would have—

Focus.

The door was reduced to wood shavings and dust. Three down, four more to go. Next was—what was next? Oh yes, McGonagall's chess.

He could play chess.

He stared at the immense dizzying black and white chessboard and why was it black and white? Why couldn't it be some other—less distracting colour? Something softer. Like blue. He liked blue. Blue was relaxing and refreshing at the same time. The best blue was the deep blue of dusk of course, when the sky was like a quiet upside ocean—

Focus.

Bloody hell. What was the difference between a bishop and a castle?

He knew this.

He could play chess in his sleep and win.

He took a deep shuddering breath.

He could—

In hindsight, he should have realised he could get past the chess set with sufficient speed and force. Of course, speed and force weren't things he had in convenient abundance—he had them in abundance, they just weren't as... user-friendly as he wished they were.

However, he didn't have much of a choice when he lost—lost! how had that happened?—and the chess set turned on him. It was true that desperate times called for desperate and he was desperate. Very very desperate.

When Quirrell staggered into the next room, behind him lay the smoking black and white rubble of what was once a magnificent chess set. And crossing the threshold, he was first hit by the stench of the troll, and suddenly he couldn't stop himself anymore. There was a forceful lurch, burning acid in his throat, and then his previous meal was on the ground, a sour taste on his tongue.

It took a moment before he fully registered what was happening—the mess on the ground changing colour, emitting a terrible smoke—and then the place lit up and then he had to process that, because the ground was blazing.

There was a troll lumbering about as gingerly as a troll could and the ground was a dense criss-cross of flaming lines.

Quirrell wanted to cry. He nearly let out a hysterical giggle. Could he give up? Could he just—let the troll hit him with its club? Surely that would be quick, if messy, but—

—YOU DARE?! YOU SWORE! YOU SWORE YOU'D—

There was really only so much screaming in his head that he could stand while already having a migraine and prickly burning skin and nausea from using magic and quite possibly the beginning stages of internal organ failure before—

—But he couldn't. If he yelled, if he actually voiced his dissatisfaction, it would be worse. He could—The Dark Lord could wreck his body more than any of these thrice-damned challenges and he wouldn't be allowed to die. His body would be forced to live on pure—tainted, corrupted, cursed—unicorn blood magic, because the—

Focus.

There was a troll and it was not big enough to cover the room even lying down. He could conjure a thick carpet. A very long one that reached the other end of the room. And he would have to run across it before it burned up. And there was still the troll. And his teeth were chattering and his hands were shaking—why were they shaking?—and he'd probably cast the wrong spell and conjure a dead tapir or something and—

There was just this room. And then two more challenges. And then he would be free.

He raised his wand, mind blank. It was starting to become a terrible habit, to cast spells he had no words for, crude magic that has no elegance or control. He doesn't think, just wills his magic—dark and beautiful, slippery yet sticky, like an oil spill in his veins, coating everything with a suffocating layer of grease—and releasing it in an explosion.

The troll falls with an ugly scraping groaning sound he didn't think trolls were even capable of making, and there's still an expanse of cursed floor he needs to cover.

He had—He had the option of attempting to conjure a thick floor covering, but even if he were successful, he didn't think he was physically fit enough to run across before it burned up—in fact, he was very certain he would just collapse and get roasted before he reached the other side.

The next option was to levitate across, but that was—he didn't think he could lose anymore dinner, but levitating was hard. It wasn't a spell he could do ordinarily, he had to borrow the Dark Lord's power for that, but he could barely stand his own tainted magic, let alone the Dark Lord's. And levitating required elegance, finesse, control—all of which he was severely lacking in right now. He would probably end up shooting himself right into the troll, or worse, the floor, and burn up anyway.

The last option he could think of was the broom in Flitwick's room. He couldn't fly. He could barely remember how his first year flying lessons went, but he did remember that he had been very bad at it. And that was back when he was still a young and healthy child, unlike the absolute mess he was now. Sometimes he didn't even know how he was still alive. How his body was still functioning, even with unicorn blood, which was almost like drinking seawater to quench one's thirst.

He could still recall the euphoric rush of magic and energy he got from drinking the silvery blood that tastes like milk and honey and wheat. He could recall how he had naively thought the curse was a myth, for it had felt like he had consumed a whole bottle of liquid luck, and he had been giddy with the joy of having strength in his limbs and waking up without aching bones and casting spells without feeling the sludge in his magic.

And then—and then it started changing. Slowly, creeping, tendrils of wrongness, dyeing his blood, bones and magic with the colour of abandonment, of weeds and fungi, dust and cobwebs. And when they tried again, to steal the vitality of a young unicorn, it seemed to work at first—for a short moment, perhaps a few minutes or half an hour—before something seemed to twist, a sharp pull like a strained nerve, and then everything splintered into a million unsalvageable pieces.

Something went wrong. Something more than the curse of stealing unicorn blood. He was sure of it. The Dark Lord was sure of it. He could feel it, the wrongness that was somehow worse. More horrifying. Like a terror unnamed and unknown but felt all the same. He didn't know if he could fix this. If he would even survive the Dark Lord's leaving. Perhaps he would just implode. Or explode. Perhaps he would slowly disintegrate into ash and dust. Or perhaps—

Focus.

He couldn't give up now. It hadn't ended yet. He'd get there when he got there but not yet. But it was almost over. Almost. He had to try, and—what was he supposed to do? Right. Get across the room. On a broom.

It took him ten minutes just to retrieve the broom and mount it, and then another five minutes just sitting on the flying object, trying to settle his queasy stomach and swimming vision. Another ten minutes later—far longer than anyone should take to get across a room of that size—he found himself staring at smudges of various colours on what he guessed must be a shelf or table.

He blinked slowly at the objects from where he sat on the floor. What were these and what was he doing here?

He shook his head and groaned, immediately regretting it. Did he have a concussion? It did feel like it. His head was throbbing and everything was blurry, and he still had no idea what he was doing on the ground, in front of some piece of furniture carrying something.

Idiot. Utterly pathetic useless—

And there was also a hissing voice which he was certain was a normal thing even though he was also hearing voices in your head was not a normal thing. It was a nasty harsh voice that seemed to scrape his bones and skin when it spoke, as if having a concussion wasn't already bad enough.

He rubbed his face and winced. His skin felt raw and wet, and looking at his hand, judging by the large red smudge in his vision, it was bleeding.

Potions! They're potions, you fool. This is Severus's room and you have to take the right one to cross!

Potions. So the colourful objects were potions. He squinted at them. Potions. Snape. Hogwarts. The Stone. He was—

He had one chance. He knew, with certainty now, he wouldn't make it. Not like this, not in his current state. He couldn't tell they were potions, much less which was the right one.

So, he reached out and grabbed blindly, then fumbled as he tried to uncork it, before gulping it down. There was a beat before the Dark Lord in his head processed his impulsive action. A beat and then—

—Everything shattered.

When Albus Dumbledore and the other Professors made their way to the third floor corridor, they first found Fluffy looking rather sleepy. A harp lay on its side on the floor some distance away, silent. No doubt that had been what Quirinus used to get past the Cerberus. A regrettably easy solution, but he was certain the remaining obstacles would prove a little more challenging, just enough to delay him and perhaps lull him into a false sense of security. The Mirror was of course the most difficult, at least for someone like Tom who would never be able to think past his hunger for power and immortality to retrieve the Stone.

Leaving Rubeus behind to coax the sleepy Cerberus, the rest of them descended down the trapdoor and—right into an angry mess of indiscernible plant matter.

"Pomona—" Albus began, as calmly as he could as he watched his robes begin to blacken and char under the harassment of what appeared to be smoking embers in the form of branches that were as irascible as the Whomping Willow was.

"Aguamenti."

When they were dropped unceremoniously by the plants that appeared to have prioritised water over themselves, they turned to Severus who stowed away his wand. He gave them the blandest look.

"Those plants were definitely not Devil's Snare," he said, flicking the sleeves of his robes that didn't seem much worse for wear. "And I have no desire to wait and see what that abomination would do with us."

Pomona huffed and frowned at the lively plants above them, in a manner rather uncharacteristic of her. "It's probably a hybrid, a cross between a Fire Seed bush and a sentient plant that seems to like humans. A remarkably successful hybridisation... I wonder who planted that."

Although none of the Professors could claim to know plants better than Pomona, they did all have an education in Herbology from their Hogwarts years, and could still recall some basic information about the Fire Seed bush.

"It's been watered recently," Filius noted. Unless the hybridisation had resulted in a tamer version of the original plant, they could all conclude that the current plants had only managed to toast their robes due to their fire being extinguished once before and were still recovering their flames. What this spelled for Quirinus who came before them was obvious to them.

The next room was Filius's, and they were greeted with the lack of a door and a missing broomstick.

"But the key is gone," he said, squinting up at the flying keys as he slowly twirled his wand. The key was gone, and yet the door was destroyed. Combined with the lack of Devil's Snare and the new addition of some Fire Seed hybrid plants, the facts pointed to the presence of a third party.

Someone had come down before Quirinus.

Beyond the room of keys was the black and white remains of a giant chess set, now reduced to rubble. Here and there, they could still make out a cracked crown or a horse leg.

"Looks like someone lost pretty badly," said Albus rather cheerfully. It was evidenced by the fact that the chess set wasn't whole. After all, it was enchanted to repair itself after a period of time. That it didn't, meant that an immense amount of magic must have been cast to not only destroy the chess set but it's enchantments as well.

Minerva looked rather pleased at that. Although not commonly known, she did prize herself in her ability to play chess, and this set had been a masterpiece.

"He should be quite worn down by now," Filius observed. "What with the burning plants and all this magic he's throwing about."

So when they reached the next room Albus could not help but feel somewhat thankful that there weren't any particularly brave first-years coming down here. He had wondered before, if any of the students would actually catch on to what was going on. He'd hoped that Hadria might. For all that she was a Slytherin, it was easy to see the Gryffindor underneath her green and silver robes. But whoever came before them had made the challenges more difficult than he would have liked for any daring student—first-year or not—to stumble upon.

The troll was lying on the ground, and emitting a heavy pungent stench. It was also smoking and turning brown and crinkly, as if it were being slowly roasted at low heat. Roasted troll, Albus observed, didn't seem like it could become a strange delicacy in any culture anytime soon.

The ground itself was covered with a dense crisscross of blazing lines that made it impossible to cross on foot without going up in flames—as it were, the troll's naturally thick hide was probably the only reason why it hadn't become a lump of black coal.

"That explains the missing broom," said Filius. "Impressive charm-work here."

"It appears our mysterious meddler might be a pyromaniac," said Severus, a calculative gleam in his eyes.

"It can't be the Weasley Twins, right?" Filius asked tentatively. But Pomona shook her head.

"Brilliant as they are when they put their minds to it, they don't have much affinity for plants." It only required skill and practice to handle magical plants for Herbology and Potions, but to successfully breed a hybrid magical plant required more gift and talent.

"They could have gotten the help of Longbottom," said Minerva, for they all knew that the plump boy was Pomona's newest prodigy. "But it still seems rather unlikely."

Because the twins have crossed many lines, but messing around with dangerous traps, set up by the Professors to guard something could easily go very wrong, and unless they knew exactly what was going on, it was a line the twins they knew would never cross. And if they knew exactly what was going on, none of this would be happening because they would inform Potter and her friends about it—particularly if they were getting aid from Longbottom—and then the rest of the Slytherin House would know, and then they would have another Howler incident. They wouldn't need concrete evidence for the parents to go up in arms over their children's safety.

After Albus took a fraction of time to unravel the Flagrante curse, they moved on to the next room where at last they found Quirinus.

Or at least, what they assumed was Quirinus.

Dressed in the tatters of Quirinus's robes was a human-shaped figure sprawled on the ground beside the table bearing six potions. There was an empty potion bottle lying on its side a short distance away from the body.

Severus was the first to approach the corpse—the other Professors were still staring at it with hands covering their mouths. Albus quickly joined him soon after, eyes grave and expression solemn.

There wasn't an inch of skin that remained unharmed. The body was covered in burns in some areas, mottled swelling bruises in others, and in many areas the veins—discoloured a strange dark-silver like ink mixed with mercury—were raised and bulging as if trying to escape his skin. His head was bare—bald and covered with a network of protruding dark-silver blood vessels and harsh red wiry fern-like marks, and his turban cloth was strewn haphazardly across the bloody mess of his face and neck.

"Late-stage of Cursed Blood," said Albus, fingers hovering above the bulging discoloured veins. "Likely stimulated by a combination of recent events. Severus, which potion did he drink?"

Severus took the bottle and examined it, frowning at the remaining drop of potion.

"It's not one of mine," he said. "It bears similarity with the Invigorating Draught but it's effects might be completely different depending on the ingredients added."

Albus watched him curiously as he gave the bottle opening a wary sniff. After all, although if the potion emitted any gas that could affect someone, it should be dispersed by now—or remain diluted in this enclosed room, in which case they would all have been affected upon entering.

When nothing appeared to happen, Severus put the bottle back on the table and began to examine the others.

"So what did it smell like?" Albus asked when it seemed like his Potions Master wasn't going to elaborate.

Severus paused in the middle of picking out the bottles of Potions that he didn't recognise.

"It's a crisp, clean, scent. A little bitter and acidic. A bit like bleach, mixed with... wet earth and grass."

In the end, after Professor Snape investigated the remains of the potion and the Headmaster had carefully examined the body, it was concluded that after repeatedly forcing his body to its limits in his usage of magic on top of the physical harm he had gained from the altered challenges, the final straw had been the potion. The potion would have given an ordinary witch or wizard a magical shock, something akin to a cup of espresso straight to the soul but with an extra kick of habanero pepper, but resulted in accelerating the Curse in his body and he died of heart failure. It was unknown whether the parasitic scrap of soul that he used to host escaped before or after his heart failure, but it seemed to have left through the front of his head, and somehow eviscerated his facial features in the process.

They burned the body three nights after, and buried the ashes—oddly damp and silvery grey—in the Forbidden Forest, in a clearing where a unicorn once died and bled and came back to life.

But they don't know that of course. They only know that blood had once been stolen there, that the unicorn that was robbed had narrowly escaped with its life, that it was now an area bearing wisps of a strange old and unknown magic that settled with the repayment of blood and ash.

- Finis -

Story notes:

1) When Quirrell felt that there was something more about the Curse than your typical Unicorn Cursed Blood, he was right. It should have fixed him for a while, like a drug you can't stop taking. But it shouldn't have gone sideways so fast like that. So why did it? Because the unicorn the blood came from, was brought back to life.

2) Bitter and earthy, acidic and grassy... these are words that can be used to describe coffee and chilli. But the truth is that I first thought of lightning and petrichor when I was thinking of suitable potion scents.

So uh, how was it? Can someone with better words help me describe this fic better because I'm sure my summary and warnings can be improved.

And if you're in need of some humour and healing, Avon_Go on AO3 has written a fic called Dimension Reise, about Hadria being transported into the world of Fantastic Beasts. Do check it out if you're interested. I had a good laugh reading it.

On another note, if any of you would like me to elaborate on something that has already occurred in the fic, or something that was brushed over and would like more information, or even a character's musings, feel free to request it in your review for the main fic. Please state explicitly that it is a request, so that I can tell which comments are just musings and which are actually requests.