Author's note: Because I've had some questions on this, I wanted to give an explicit answer: yes, students take their OWLs in third year and NEWTs in fifth year in this AU as the Hogwarts curriculum has been condensed as part of wider changes to the world and setting. Never fret - this story still has seven books! Thank you all. I appreciate the engagement!

Chapter 25 – Sneaky Slippery Slytherins

Harry had the rest of the weekend free from participation in any Triwizard events. Instead, he joined his friends in the stands to watch the first leg of the standard speed race on Sunday. Having flown the course three times already, Harry wasn't overly excited to watch the standard flyers go over it again. Especially not on their much slower brooms. In the end, it wasn't so bad, and Harry got to appreciate the speed course as a spectator, which he supposed was nice. Watching the race on the Whizzers was certainly not as exciting as actually flying it, though.

Three competitors from Hogwarts went through to the second round – Draco and both Weasley twins.

After that it was into the next week at school where the teachers had started to ramp up the difficulty of their classes. By the time Wednesday morning came, Harry looked forward to hours of mindless speed racing at the weekend. Unfortunately he still had three full days of lessons ahead of him before he could do that.

Including a couple of lessons with Mad-Eye Moody.

"Do you think Moody's going to be ... you know ... today?" said Theodore on the way to Viper group's Wednesday morning Defence lesson.

"Today's lesson is about the War," said Blaise, "so I think so, yeah."

"Moody isn't that bad," said Daphne. "He's just a bit ... rough ..."

Harry scoffed. That was an understatement – Moody was quite probably the roughest teacher Harry had ever had, and that was including a particularly abrasive games teacher at Stonewall High.

"All his bloody lessons are about the War," muttered Theodore. "Wish he'd talk about something else for once."

Harry got where Theodore was coming from. He didn't like it overly much either, as Moody usually managed to drop in bits and pieces about Harry or his parents' roles in the War into most of his lessons. It was all information Harry would have wanted to know, just not in front of the entire class.

Too many eyes staring at him.

Still, at least Harry's parents had been on the right side of it – something that couldn't really be said for Draco, Vince, or Theodore's fathers. Even if Theodore's dad had only been accused, Moody didn't seem to believe in his innocence.

Although to be fair, Harry didn't either.

"This lesson is going to be on the convicted Death Eaters in Azkaban," said Tracey, "so I think his attention will be on that, this time," she offered.

Theodore didn't seem convinced.

The Slytherins filed into the Defence classroom as soon as they reached the door, having learned over the past months to get to Defence as early as possible. Most of the time they made it in before the Hufflepuffs, which at least meant Moody didn't take points. The Hufflepuffs arrived not long after and Moody started the lesson by slamming shut the door with a jab of his wand.

He stood up and walked in front of his desk, then leaned back against it.

"Alright, listen up," barked Moody. "We've got a meaty lesson today and only an hour to do it, so I want eyes on me. Today's lesson is about the Death Eater bastards locked up in Azkaban and all the shit they did to get them put in there. Tomorrow's double session we'll go much deeper into two notables—Bellatrix and Rodolphus Lestrange—but for today, an overview's all we need. So don't worry yourself, Malfoy – you'll get to show off everything you know about that aunt of yours tomorrow afternoon."

Harry glanced over to Draco, who as usual for Defence classes wore a poorly disguised scowl across his face. He knew better than to react to Moody's prodding, however, so simply stared ahead.

"Write this down. Four names. Rodolphus Lestrange. Bellatrix Lestrange. Augustus Rookwood. Bartemius Crouch Junior. Aye, that's right—old Barty Crouch's lad, for those of you who pay attention," continued Moody. "You'll have seen him around the castle this year, old Barty. Never especially mellow, his lad going Dark did nothing to help."

"We'll start with Rookwood. Tricky fucker, Rookwood. He was an Unspeakable for years. No one knew he was a follower of You-Know-Who until after the War had already ended. Now, I know a bit about his work in the Department, right—I had basic clearance, didn't I?—but there's not much of it I can share, and more that I don't know. What I will say is, it was a whole load of real sensitive stuff. It ain't for no reason they call it the Department of Mysteries, yeah?" said Moody.

"Rookwood's a master Occlumens, so we ain't ever managed to pry much from that head of his, but as far as we can tell, he was recruited to You-Know-Who's service personally by the big man himself. Smart feller, Rookwood – went to Ravenclaw as a lad, long time ago now – got head-hunted by a former D-o-M Head right out of school. Never showed any of the traditional signs of being a Dark wizard—we covered those a few lessons ago before Christmas, remember—never got mixed up in petty crime, nothing like that. As far as everyone around him could see, Augustus Rookwood was a model citizen. Friends with everyone, not an enemy to his name."

Harry took down notes on everything Moody said, including a large, circled, note to himself to look up what an Occlumens was later on. Moody hadn't elaborated, so it had to be something everyone else would know about, and Harry didn't want to look a berk.

"Good job, brilliant contacts, well-respected family background. Wife, no kids—until the end of the War, anyway. So, what turns a wizard like Augustus Rookwood Dark? That's the thousand Galleon question, innit? Make no mistake, Rookwood is Dark. No one pressured him. No one forced him into it. He wasn't Imperiused—didn't even claim to be," continued Moody, leering at Draco. "So why go Dark?"

"What we think—and remember, Rookwood's an Occlumens and You-Know-Who never gave interviews—is that Rookwood was given the opportunity to perform 'free and unrestricted' research into any and all subjects he wanted, with a never-ending flow of resources from You-Know-Who's war chest. Funded largely by Malfoy gold. That ain't slander either, lad—it's in the historical record," Moody said, pre-empting any protests from Draco. "Now I'm sure you've all heard no end of stories about the D-o-M, but let me tell you this—there's laws and rules and regulations they have to follow in their research and other activities. So, yeah, there's oversight—even if some people don't think there's enough."

"So this offer was a good one for someone like Rookwood. He obviously had Dark tendencies, inclinations nobody ever knew about. See the sort all the time—they've got ideas, cravings even, but never get to act on 'em. You-Know-Who used those to get him on side, offered him something no decent wizard was ever going to. We reckon Rookwood took the Dark Mark some time in the sixties, not sure on the year. It ain't like the Death Eaters kept records, is it?"

"Rookwood passed information from the Department to You-Know-Who for years. He was one of the Death Eaters' most useful—and highly placed—spies. More than that, from what we've been told by other Death Eaters and other intelligence the Auror office was able to gather, Rookwood was personally responsible for some of the nastiest shit unleashed during the War. The muggleborns here won't ever have heard of this since we struck it from all muggle records because it was so heinous, so vile, that it was impossible to cover up properly otherwise. But Rookwood was behind the Hull Massacre in '78. Forty-nine Muggle children were rounded up and tortured using innovative new Dark spells of Rookwood's invention. I won't go into detail—the Board wouldn't give permission. But Rookwood didn't develop these spells out of nowhere."

"The Auror office managed to trace—after the War, mind you—Rookwood to the disappearances of no less than seventeen muggle children over a ten year period leading up to 1978. He'd been researching, practising, testing these spells out for a decade while employed at the Department of Mysteries. Now, I ain't been telling you lot this to make you upset or scared. That's not my job, and I don't want it to be," said Moody. "But the story of Augustus Rookwood is a good one because it shows how even a 'good', 'normal,' 'respectable' wizard can be secretly Dark. This is why I say—and people mock me for it, but I ain't dead yet so I must be doing something right—constant vigilance. The Dark is insidious, worms its way in where you'd never expect it to be."

Moody stood up from where he leaned against his desk.

"And you know what's even worse? We may never have caught Rookwood. His identity was secret, not known to many Death Eaters at all. You know which Death Eater gave us his name? Igor Karkaroff. Aye, that's right—Durmstrang's headmaster, the very same man sat in the Great Hall at breakfast this morning and every other morning since he arrived here. Not through any altruism on his part, mind you—he just wanted to save his own arse, didn't he? Managed it, too. But when I think that there might be others out there we did never catch, it makes my skin crawl. So let the story of Augustus Rookwood be a lesson to you—sometimes the Darkest wizards blend right in."

Harry wrote down everything Moody had said, his stomach churning at the thought of a massacre so vile it couldn't even be covered up with a muggle-friendly excuse. All those muggle families who'd never know the real reasons their children had gone missing. Never even knew they were dead, always hoping…

Even Rookwood's own son, that first year Slytherin, who would have had to grow up with his father in Azkaban for crimes more abhorrent than all the other Death Eaters. Whispers from the more polite, pointed comments from the others. It couldn't have been easy.

Harry put up his hand to ask a question.

"Aye?" said Moody, nodding towards Harry, his electric blue fixed on Harry's face.

"How did Voldemort know to target people like Rookwood, if they've never shown any signs of Darkness? Wouldn't it be quite risky for him to do it?" Harry asked. "Especially earlier on, when he was trying to keep everything a secret." He ignored the gasps – mainly from the Hufflepuff side of the room since they weren't as used to it – at his mention of Voldemort's actual name.

"Aye, good question," said Moody. "You might think he did his research, had good reasons for everyone he approached... but the truth is, You-Know-Who tried to recruit just about every pureblood and a good deal of the halfbloods, too. He even tried to recruit your dad, Potter, though the Lord only knows what he was thinking there. Cast a wide enough charm and you'll catch something with it, I suppose. I heard tell he even tried to recruit your mum, though that would have been a rarity."

Harry hadn't known Voldemort had tried to recruit his father. It made a certain sort of sense. His mother, though… that was strange. More than strange. He scribbled a note onto his parchment to look it up later.

"Moving on," said Moody, "let's talk about the Lestranges—Bellatrix and Rodolphus. We can talk about Rabastan another time. We'll go in-depth tomorrow like I said, so for now, an overview of their activities during the War. Bellatrix Lestrange—that one's mum's sister," Moody said with a jerky point towards Draco, "was one of You-Know-Who's top Death Eaters. Maybe even the most important. Contrary to what we saw with Rookwood, Bellatrix Lestrange showed all of the signs of being a Dark witch from a very young age. 'Course, with a family like hers, a lot was kept secret and only came out later. But if we go through the list, we can see that young Bellatrix Black as she was then ticks off every one: a fondness for hurting small animals—she was caught while at school torturing rats in the dungeons as 'Defence practise'; a talent for and propensity towards manipulation of others, visible in her activities throughout her life including while at school; a chronic lack of remorse for anything she's done, we saw from her statements during her trial; a delight for Dark magic and the list goes on and on."

Moody paused.

"I could—and will, tomorrow—spend hours detailing just why Bellatrix Lestrange is one of the worst Dark witches to have ever been produced on these islands. Maybe anywhere. But today we'll discuss in brief. Now, again, nothing like Rookwood, Lestrange's role in the Death Eater organisation was known from very early on. She was part of the second generation of Death Eaters but rose quickly to become the 'Dark Lord's' top enforcer and lieutenant when his first lot of followers lost their shine."

Moody went to continue his lecture, but Draco interrupted him.

"Professor," Draco said, his arm in the air.

Harry glanced back at him. Draco almost never asked questions in lessons, and certainly not in Defence with Professor Moody. Usually, Harry thought that was because Draco thought it beneath him, but drawing attention to himself in Moody's lessons seemed suicidal. Moody seemed just as shocked at Draco's sudden desire to contribute to the lesson as Harry was.

"Got something wrong, have I?" said Moody, his remaining eyebrow raised.

"No, Professor," said Draco, his voice steady and his tone quite unlike his usual drawl. "I wanted to ask a question. What happened to the Dark Lord's original followers? Most of them are never mentioned in the history books or even the trial records. Why was someone like Bellatrix Lestrange allowed to rise so high when there should have been more than enough loyalists to fill any gaps from the Dark Lord's closest followers? The ones who had been with him longest, I mean."

Moody remained silent for a few moments, both of his eyes focused on Draco. He leaned forward, stared for a while, and then he nodded. He leaned back against his desk.

"We know that the first generation of Death Eaters, strictly speaking, weren't involved in the War. I've got to be careful answering this, mind, since some of the things I could say would actually be slanderous, since we weren't able to get enough evidence to convict. But some of them ended up being respectable family men, men of good standing in their communities—and You-Know-Who wanted to use that, so he didn't lean on them for less savoury things." He paused, clearly thinking through how to word his statements so that he couldn't be accused of slander.

"The Auror office has... reason to believe... that some of these early Death Eaters brought their kids in to serve You-Know-Who instead of them. I'd name names but we weren't ever able to prove a direct..." Moody shrugged. "Others he discarded like bits of rubbish—like Hannibal Avery, who was Kissed for the murder of Amaranthus Boake which he sure as shit didn't actually do. And he got paranoid later on, see—all Dark wizards get there eventually. So You-Know-Who had to recruit younger, newer blood. Wizards and witches ready to risk it all on raids, young enough not to worry about consequences."

"As to why Bellatrix Lestrange specifically... She was talented and obsessively loyal to the cause. Now, I ain't saying I approve, but Bellatrix Lestrange was good. A near-psychotic danger to everyone around her, but she was a witch of rare talent. A real terror in a fight, let me tell you—point to any number of scars on me and it's her who gave them to me. But the Auror office first got an eye on Lestrange after the Battle of Gamp's Bottom, one of the earliest skirmishes in the War proper. Before Gamp's Bottom You-Know-Who had kept to the shadows, his Death Eaters making precise, strategic strikes on targets, engaging in raids—typical shadow war stuff, yeah?"

"Gamp's Bottom was supposed to be another secret raid on a wizard—William Whitefeather, a pureblood wizard whose crime was bringing his muggle wife to live in Gamp's Bottom. At the time, Gamp's Bottom had no muggles or squibs living in it. You-Know-Who wanted to send a message. So he sent in a young lot of Death Eaters led by Rodolphus Lestrange for a nice bit of muggle torture. They didn't expect to be met with any resistance, but a vigilante group had already moved the family out of the house before the Death Eaters arrived. What followed was a proper battle. We'll go into more detail tomorrow, but of the five Death Eaters sent in, only Bellatrix and her husband Rodolphus survived, largely due to Bellatrix's actions that night. The Lestranges were identified by Aurors leaving the scene, and from then on, both of them were utterly devoted to the Dark Lord's cause. So really, there wasn't anyone better."

Throughout his answer to Draco Moody hadn't once looked away from the boy, not even with his electric blue eye that usually whizzed about looking anywhere and everywhere.

"That answer your question, Malfoy?"

Draco nodded. Moody pulled out a little pocket watch from his robe pocket and then frowned.

"Yes, Professor. But I had another question—"

"Save it for tomorrow. We ain't got much time left and I wanted to at least cover Crouch Junior this morning."

Draco didn't seem pleased by the brush off, but Moody went on ahead in his lecture regardless. Harry listened half-heartedly, manging to write down some of what sounded most important, but he couldn't stop glancing over at Draco, whose face alternated between a picture of serenity and barely concealed rage.

At the end of the lesson Draco hurried away with the rest of the Slytherins on their way to a double Potions session with Snape but broke away from the group near the Entrance Hall. Harry watched him go, and then decided to follow.

"Er, tell Snape I had to—ah, I had to nip to the loos," Harry said to Theodore. "Proper emergency. Won't be long."

Then Harry followed Draco at a reasonable distance, slow and careful not to be seen. He thought perhaps he should start bringing his Invisibility Cloak more places with him. Draco didn't use the main staircase as he went back up through the castle. Instead, he ducked into hidden passages and lesser used corridors with access stairs, most of which Harry had never had any cause to use before. Some of them were poky and narrow, places Harry didn't think were really meant for general use, but they led to the same sort of exquisitely decorated, expansive corridors and halls found in the rest of the castle. Many of them were new to Harry.

Draco – and Harry after him – passed by a few other students, mainly stragglers on their way to lessons, but Draco had picked a route through the castle that seemed little used by its denizens and so there weren't very many others at all. Draco appeared unconcerned with being seen, at least not when he wasn't about to enter a concealed doorway or passage, which made it rather a lot easier for Harry to follow without the aid of his Cloak.

Harry followed Draco into one thin passageway that wound upwards and assumed that Draco was once again going to wherever he went on the seventh floor. The passage split in two halfway along, with Draco nowhere to be found. After a brief moment's hesitation, Harry took the leftward turn that kept him moving upwards.

The passage terminated on the fifth floor adjacent to the main landing. Once Harry reached the main stair he saw that Draco had decided to use it to access the seventh floor, so Harry waited a few moments and then followed.

What's on the seventh floor? Harry wondered. As far as Harry knew, there were very few things on the seventh floor for students to be interested in, especially Slytherins. There was Trelawney's Divination classroom, her quarters, and her office; everyone said Gryffindor House was somewhere there, perhaps in one of its four towers; a handful of classrooms; and a gallery overlooking a paved courtyard – none of which sounded particularly relevant to Draco. Harry thought that meant Draco must have found some kind of secret chamber, or at the very least a passage to a hidden chamber.

For what purpose, Harry could only speculate. But he didn't think it innocent.

When Draco reached the same corridor Harry had lost him before – the one with the tapestry of the dancing trolls set opposite a bare wall – he looked around before doing anything else. Harry ducked behind a statue and kept watch, determined this time not to lose Draco. Draco glanced towards each end of the corridor, then eventually paced along it from one end to the other three times. Then he disappeared into a new door opposite the tapestry, which vanished as soon as Draco had used it.

Harry waited a few moments and then made his way to where the door had been just before. Harry tapped at the wall and found that it wasn't a false wall – at least, not that he could tell. There was no indication that the wall could reveal a door. Harry tapped it with his wand, but nothing happened.

Draco walked up and down the corridor three times, Harry remembered. Harry copied him, but nothing happened. He tried it again, this time thinking about manifesting a doorway, but again nothing happened.

There's got to be some trick to it, Harry thought. Something Harry wasn't getting, something Draco had thought, perhaps. A strange sort of password for a door, one that didn't have any words, but then, that wasn't so strange at Hogwarts. Not when there were rooms that only opened if you tickled a pear.

Harry glanced at his watch. He was nearly twenty minutes late to Potions with the Ravenclaws, which was salvageable if he really leaned on having an upset stomach. He would have skipped it, but this year Tracey was his partner and Harry didn't want to leave her to do the whole potion alone.

Harry sighed and headed back down towards the dungeons, secure in that knowledge that he at least knew where Draco was going, even if he didn't know how he got there. That was something.

Harry made it back to the dungeons in good time using the direct passage he'd discovered the last time he followed Draco and stopped only briefly to dust himself off before entering the Potions classroom.

"I'm really sorry I'm late, Professor," Harry said, hoping that he sounded appropriately contrite, "but I had an, er, toilet emergency."

A few of his classmates snickered at that, but Harry didn't mind. It was a good lie because it was embarrassing. Snape, however, didn't seem particularly convinced.

"Detention this evening for lateness, Potter," Snape said eventually. "After dinner. Now get to work—this potion is difficult enough without you causing more work for Miss Davis."

"Er, yes," said Harry. "Sorry, Professor."

He crossed the potions laboratory to take his seat next to Tracey at their workbench.

"You okay?" whispered Tracey as Harry tried to get up to speed.

"Yeah, yeah, it's fine," Harry said. "Sorry I'm late, I was just... er, well you heard," he said. He didn't want to tell Tracey what he was doing, or what he thought about the Malfoys and their connection to Voldemort's current plans just yet. He wanted something more concrete before he said anything to anyone, even though Tracey knew more about anything than anyone else. "What do you need me to do?"

"Chop these and crush those," said Tracey, gesturing to two separate piles of ingredients on their bench. "We're running a bit behind because it was just me here," she said, "but now that you're back we should be able to catch up!"

"Right, okay," said Harry. He forced thoughts about Voldemort and the Malfoys out of his head, and instead set to work on the tasks Tracey had had to do on her own. By the end of the lesson they'd just about managed to produce a passable potion, and Harry placed a vial of it onto the rack on Snape's desk just as the lesson ended.

Snape stopped Harry just before he got out of the door.

"Detention this evening, Potter! Don't forget."

Harry stopped at the threshold to the classroom and nodded at Snape.

"Of course, Professor."

Then he left with the rest of his friends on their way to lunch, the seeds of a plan germinating in his mind. Harry would bring his Invisibility Cloak to the detention, then use it to go and figure out how the chamber on the seventh floor worked.

Harry thought perhaps being late to Potions had worked out better than he could have expected, then, given this new opportunity. Detention with Snape would be awful, but it did give him an excuse to be out of the Common Room after hours...

After dinner finished Harry reported to Snape's office. He took his schoolbag with him even though he knew Snape rarely assigned lines, purely so he had somewhere to hide his Invisibility Cloak. Harry knocked on the door and waited to be called inside.

"You may enter."

The door opened and Harry stepped inside. Snape's office was much the same as it had been the previous year – spartan and almost completely devoid of personal touches. A perfectly functional space that betrayed nothing of the man who sat in it.

Except a proclivity for bland decoration, Harry supposed.

"I'm here for detention, Professor," Harry said.

"Very well. Follow me, Potter," Snape said. He stood up from his desk and led Harry to one of the potions prep rooms along the Potions corridor. He ushered Harry inside and then closed the door behind them.

"I would not usually trust such tasks to students on a detention," Snape said, "as they are ordinarily lacking in skill or sense—but you possess some ... small ... amount of proficiency with potioncraft and it is a task which I need done." Snape gestured to a series of small boxes set atop the large prep workbench at the centre of the room. "I wish for you to prepare these ingredients for use in first-year classes. It is a task requiring no more than an adequate grasp of second year potions skills, which you have shown yourself to possess. You may leave when you have finished."

That had quite possibly been the most complimentary Snape had ever been about Harry's performance in Potions. It still wasn't much, but it was more than Harry had expected.

"Er—thanks, Professor. I'll just get started then, shall I?"

Snape turned and left Harry alone in the prep room, slamming the door shut behind him. Harry stared at the door for a while after Snape left, drawn back to the conversation he'd overheard between the Potions Master and Igor Karkaroff at Christmas time. Somewhere on Snape's arm was the Dark Mark, Voldemort's brand that signified he'd been a Death Eater.

Is he still a Death Eater? Harry wondered. Nobody knew. Concrete information on Severus Snape and his role in the War was difficult to find, and Harry had certainly tried to find it. Some said he was a Death Eater; some said he was a spy amongst the Death Eaters; others that he was a spy for the Death Eaters. Dumbledore seemed content to trust Snape, but from where Harry was sat Dumbledore often made strange decisions for all sorts of obscure reasons. Dumbledore could know Snape was a still a Death Eater and still keep him on the staff for perfectly good Dumbledorian reasons.

It's not like I'll figure it out sat here, though, is it? thought Harry.

With a sigh Harry went to look inside the boxes to see what he needed to get done before he could go and look for the secret room on the seventh floor.

He pulled open one box to find it stuffed to bursting with dead toads. 'Toads for pickling', Harry read with a grimace. He tackled the next box. 'Pixie wings for grinding', apparently. After looking at all of the tasks he had to do, Harry reckoned it would take him perhaps two and half hours to get all the jobs done.

He set about getting all his assigned tasks done as quickly as possible. Pickling toads was easy enough – he just had to dump them into the pickling fluid and seal them up, preferably without spilling anything over his robes. Grinding up pixie wings was a bit more laborious but still ultimately simple work, although plucking out newts' eyes without bursting them was more of a challenge. Harry finished a bit after nine o'clock, packed everything away, and then left the prep room. He checked first to see if anyone was around, then ducked into a dark alcove to don his Invisibility Cloak.

Harry had been thinking of how to access the secret chamber on the seventh floor for most of the day. There was obviously some trick to it, or a password of some kind, as was the case with every secret or concealed passage or room in Hogwarts. Draco had walked up and down the corridor three times and a door had appeared; when Harry tried the same thing, nothing had happened.

Harry had ideas about why that had happened, of course. Perhaps the room could only be used by a single person at a time; maybe there was a password to say or think as well; maybe any number of things, some more esoteric than others. But Draco had obviously figured out how to gain access to the room, or at the very least someone else had who had then told Draco, so Harry didn't think it was an impossible task.

Fortunately Harry had his Cloak and an abundance of time to try and figure it out. He set off for the secret passage direct to the seventh floor he'd found following Draco while he mulled over how to get into the room.

Harry paused when he heard a voice near the dungeon level boys' toilets. It was probably a prefect, maybe two, and he didn't want to risk being caught even though invisible.

"...nothing to eat... no speakers... so lonely..."

No, Harry thought, not a prefect at all. The snake.

Although Harry did very much want to figure out what Draco was doing on the seventh floor, he also wanted to find the snake. The secret snake that lived in the dungeons and had, apparently, spoken to people before. He agonised over the decision for a few moments until he decided to follow the snake. The seventh floor was going nowhere, after all, and Harry had lost the snake before. And it was always hungry, so might even die if he didn't find it.

"...wait, wait, wait... I have waited so long... where is my speaker?"

The snake was moving upwards, as far as Harry could tell, roughly in the direction of the kitchens.

How's it moving about, then? Harry wondered. He didn't think it was slithering about the hallways and corridors. He'd never heard anyone in the entire castle ever mentioning seeing snakes roaming about, only spiders and the occasional mouse. Or rat, Harry thought, remembering Wormtail.

Harry wondered if it was moving through gaps in the walls and floors, although he didn't think there were any of those in the dungeons, just solid stone. Elf passages, maybe? Harry wished he had a map of the castle.

Harry rushed towards the little passage which led from the dungeons to the cellars. It opened up close to the kitchens themselves, and Slytherins often used it to go and grab a night-time snack from the elves using a route teachers didn't ordinarily patrol. Tonight, however, Harry used it to follow his unseen snake.

The snake didn't stick around near the kitchens for long. Fortunately it seemed quite talkative, at least as far as snakes went, so Harry had some idea of where it was going. It was lonely, perhaps. Wanted someone to speak to.

"...don't want to sleep anymore..."

The snake kept moving upwards, hissing its complaints and worries as it went. Unfortunately for Harry there was no convenient hidden stair leading from the cellars to the castle's ground floor, so he had to set off at a quick pace towards the main staircase up from the lower levels.

Harry followed the snake up from the Entrance Hall, through a winding path on the first floor that went through a series of different spaces, and then up once more to the second floor.

"...back to the nest, alone..."

Harry recoiled as he stepped into a puddle of fetid water. He caught the tail-end of the snake's monologue as he entered the disused and damp corridor.

"...so hungry..."

Harry tiptoed through the puddles of water lining the unpleasant abandoned hallway until he reached the doorway which was the source of all the water. Harry paused before going any further. Everyone knew about the haunted girls' toilet on the second floor, and everyone also knew to avoid it. All of the girls said that they would rather be late for lessons than ever use Moaning Myrtle's bathroom. But the snake had gone quiet once it reached the approximate location of the haunted toilet, so Harry thought perhaps its nest was in one of the toilets.

He took a deep breath and went inside. With any luck, the ghost inside would be off doing whatever ghosts did at night, and Harry could have a look around unmolested. Once inside Harry pulled the Invisibility Cloak's hood down so it wouldn't get dripped on.

The bathroom looked like any of Hogwarts's other bathrooms, just with a layer of grim overlaid upon everything as it seemed even the house elves avoided it. A few inches of water covered the floor, and Harry heard the drip-drip-drip of several leaky taps. One of the toilets seemed stuck on the flush, and spewed water into the rest of the room.

That'll be why it's wet, then, Harry thought. What a pleasant place for a piss…

Harry pictured a snake in his mind and then attempted to speak Parseltongue.

"I'm looking for a snake. Is there one in here?" Harry asked. Parseltongue was instinctive to him when he was looking at a snake, but otherwise, Harry had no idea whether or not he was speaking the language.

A keening wail sounded from one of the toilet stalls. The blurred form of a ghost shot out of the toilet stall and whizzed around Harry, eventually coming to a stop right in front of Harry's face.

"Just who do you think you are coming in here and hissing like that!" screeched the ghost – Moaning Myrtle, Harry assumed, although he'd never met her before. "Well? Well?"

Harry banished thoughts of snakes from his mind so he could speak in English.

"Er, look, I'm really sorry," he said, "I didn't mean to, er, intrude on your..." He paused. What would he say? 'Sorry I interrupted your unlife, but…' "I was just looking for..."

"Sorry? Sorry? You're sorry that you came in here to disturb my death?" cried Myrtle, once again circling around Harry. "Poor despicable Myrtle, can't even cry about her own death in peace! Well? Are you here to remind me of how I died? Laugh at the silly dead girl?"

"Er, no, no!" said Harry. He backed away from Myrtle slowly. "Nothing like that at all! I don't even know how you ... died... and I'd never just come in here to, er, laugh at you."

Myrtle didn't seem especially convinced, but she did at least stop screaming, which Harry counted as a win. If only she'd stop whirling about…

"Then why did you come in here hissing like that?" she questioned. "And do you know you're mostly invisible?"

"Er, yeah—I'm invisible on purpose," Harry said. "And I was just looking for a snake, actually, that's why I was hissing. It wasn't to... You haven't seen one, have you?" He wanted to get Myrtle off the topics that clearly distressed her and onto something which might result in less shouting and crying. And which also involved the snake he'd followed – perhaps unwisely – into the haunted girls' toilet.

"A snake?" said Myrtle as she whizzed around the bathroom and ended up back in front of Harry. "There aren't any snakes in my toilet," she declared. Then she did a little loop as she thought about something else. "But there used to be a boy, he was a Slytherin like you, who came in here hissing sometimes. That's why I thought..."

Now that was something that interested Harry. Another Parselmouth at Hogwarts? Ghosts had a poor sense of the passage of time, Harry knew, so Myrtle could have been talking about someone long dead or someone she'd seen that very morning.

"Really? When was the last time he came in here?" Harry asked. The only other Parselmouth Harry knew of within living memory – with the possible exception of Harry's own mother – was Voldemort, which would make the undead wizard the snake's 'speaker'. A Slytherin boy couldn't have been Harry's mother, so it had to have been Voldemort.

"The day I died!" screamed Myrtle, right into Harry's face. She retreated to her toilet stall and hid inside the U-bend.

That didn't go quite how I wanted it, Harry thought with a frown. But at least the hysterical ghost had gone and Harry could have a little look around the bathroom just in case there was a snake lurking somewhere.

But there wasn't, not in any of the toilet stalls or around the drains or anywhere Harry could see. Although Harry was very interested in the hissing Slytherin Myrtle had seen the day she died, the ghost didn't appear to be taking visitors any longer, so Harry pulled up his hood and left the bathroom.

He hadn't managed to figure out how to open the secret room on the seventh floor, and he hadn't even found the snake that had distracted him from his earlier goal. Still, he couldn't help but feel he'd achieved something that night even if he wasn't sure what yet.

Harry returned to the dungeons, narrowly avoiding Filch on patrol with his cat in the Entrance Hall and stuffed his Invisibility Cloak into his bag before entering the Common Room. It was late, but still early enough that none of his dorm mates had gone to bed yet.

Harry joined his friends at a table in the Common Room.

"Detention go well?" asked Blaise.

"Snape had me pickling toads," Harry said. "Only just finished. What are we up to here?"

"Theodore's trouncing me at chess," said Blaise, nodding towards the game on the table. "Honestly I was about to quit."

"No need," said Theodore, "I've just won. See?"

"Ugh, great," said Blaise. "I don't want to play again."

"Harry? Chess?"

"Er, yeah, alright," said Harry.

He spent the remainder of the night until bedtime getting beaten at chess by Theodore, although the only thing Harry could really concentrate on were his thoughts on how Draco's behaviour, and the snake in the dungeons, could relate to Voldemort and his plans.