The Writing on the Wall

Castiel backed up against the un-graffitied part of the wall, but had nowhere to hide. He could feel the hundreds of eyes on him and felt his chest constrict. Gabriel detached himself from the crowd and crouched in front of Castiel, yellow prefect badge flashing.

'What happened?' he asked in a low voice. Castiel shook his head and squeezed his eyes shut, trying to block out the feeling of being watched. Gabriel grimaced.

'What's going on here? What's going on?'

Attracted no doubt my Malfoy's shout, Argus Filch came shouldering his way through the crowd. Then he saw Mrs Norris and fell back, clutching his face in horror.

'My cat! My cat! What's happened to Mrs Norris?' he shrieked. Castiel shrunk away from Filch, whose popping eyes fell on Harry.

'You!' he screeched. 'You! You've murdered my cat! You've killed her! I'll kill you!'

'Back off!' Gabriel said loudly, standing between Filch and Harry.

'I'll kill him! I'll-'

'Argus!'

Dumbledore had arrived on the scene, followed by a number of teachers. In seconds he had swept past the Gryffindors and Sherlock and detached Mrs Norris from the torch bracket.

'Come with me, Argus,' he said to Filch. 'And you six.'

'Headmaster, may I come as well?' Gabriel asked.

'No, Gabriel. I need you and the other Prefects to make sure the students are back in their dormitories.'

'Yes, sir.'

Gabriel turned to Castiel.

'Listen, you haven't done anything wrong, okay? You'll be fine,' he said bracingly.

Castiel nodded and Gabriel patted him gently on the shoulder, before going to shepherd the rest of the students away.

Lockhart stepped forward eagerly.

'My office is nearest, Headmaster- just upstairs-please feel free-'

'Thank you, Gilderoy,' said Dumbledore. John walked beside Castiel, whispering a stream of encouragements to him as they went. Lockhart, looking excited and important, hurried after Dumbledore. As did Professors McGonagall and Snape.

As they entered Lockhart's darkened office, there was a flurry of movement across the walls. Several of the Lockharts in the pictures were dodging out of sight, their hair in rollers. The real Lockhart lit the candles on his desk and stood back to allow Dumbledore to lay Mrs Norris on the polished surface. Harry, Ron, Hermione, and John sank apprehensively into chairs, and Sherlock sat, cross-legged, on a table. Castiel, again, backed into a wall and hoped he would melt out of sight. He couldn't keep his eyes off of Mrs Norris and imagined a look of terror on her feline features. He held his breath while Dumbledore examined her. The silence was heavy and tense and all eyes, even the Lockharts on the walls in the pictures who had pulled their rollers out, were fixed on Dumbledore and the cat. Professor McGonagall was bent almost as close as Dumbledore, Snape lurked in the shadows with a peculiar expression on his face- as if he were trying to cover up a smile- and Lockhart buzzed around them, making suggestions.

'It was definitely a curse that killed her- probably the Transmogrifian Torture. I've seen it used so many times, so unlucky I wasn't there; I know the very counter-curse that could have saved her.'

'Are you aware that you're talking out loud, or do the words just skip your brain and go straight to your mouth?' Sherlock said abruptly to Lockhart. Hermione gasped and Castiel slid down the wall slightly out of shock. Professor McGonagall frowned at Sherlock, while Lockhart flicked a sharp glare at him, though he soon concealed it with his previous excited expression. Filch, however, paid no attention, as he was too busy crying loudly with his hands over his face.

Dumbledore muttered some strange words and tapped Mrs Norris with his wand, but nothing happened.

'I remember something very similar happening in Ougadougou,' Lockhart said, 'a series of attacks, the full story's in my autobiography. I was able to provide the townsfolk with various amulets which cleared the matter up at once.'

'Please, do shut up,' Sherlock snapped. 'Are you telling me that this was the best you could find?'

'That is quite enough of that, Mr Holmes,' Professor McGonagall said sharply. Sherlock closed his mouth but looked as if he badly wanted to stop talking. John shook his head slightly, hoping Sherlock was looking at him. They suffered through another painful silence- punctuated by Filch's dry, racking sobs- until Dumbledore straightened up.

'She's not dead, Argus,' he said softly.

Lockhart's head snapped to look at him.

'Not dead?' choked Filch. 'But why's she all stiff and frozen?'

'She has been Petrified,' said Dumbledore.

'Ah! I thought so!' Lockhart said promptly. Sherlock's mouth fell open in contempt and then twisted into a sneer. John cringed slightly, praying Sherlock would never look at him that way.

'You are an absolute moron! I'd rather have no teacher at all than be taught by you!' Sherlock said with unnecessary aggression.

'Ten points from Ravenclaw,' McGonagall said furiously, nostrils flaring.

'What's the matter with you?' Hermione whispered once the teachers had turned their attention back to the cat. Sherlock didn't answer, his jaw clenched in anger.

'Yes, she has been Petrified, but how, I cannot say,' Dumbledore continued.

'Ask them!' shrieked Filch, turning his blotched, tear-stained face to Harry and pointing a shaking finger at both him and Castiel. Castiel's knees turned to jelly and his fingers clutched at the wall behind him.

'No second-year could have done this,' said Dumbledore firmly. 'It would take Dark Magic of the most advanced-'

'They did it! They did it!' Filch spat. 'You saw what they wrote on the wall! They found-in my office-they know I'm a- I'm a- they know I'm a Squib!'

'For goodness' sake, pull yourself together! Not everyone's as prejudiced as you are. A couple of twelve-year olds aren't going to Petrify your cat just because you're a Squib,' Sherlock said. 'Looks like we found someone almost as stupid as you,' he shot at Lockhart.

'Detention, Holmes. Go and wait outside,' Professor McGonagall snapped. Sherlock stormed from the office.

'What was that about?' Harry asked once he'd gone. Everyone except Filch looked at John, who crossed his arms defensively.

'What? I don't know. Why would I know?'

'This isn't about him!' Filch shouted impatiently. 'This is about them, and what they did to my cat!'

'I never touched Mrs Norris!' Harry said loudly. 'Neither did Castiel, and I don't even know what a Squib is.'

'Rubbish!' snarled Filch. 'They saw my Kwikspell letter!'

'If I might speak, Headmaster,' said Snape from the shadows. The sound of his voice made Castiel want to shrivel up until he was small enough to be invisible to the naked eye.

'Potter and his friends may simply have been in the wrong place at the wrong time,' Snape continued, a slight sneer curling at the corners of his mouth, 'but we do have a set of suspicious set of circumstances here. Why were they in the upstairs corridor at all? Why weren't they at the Hallowe'en feast?'

Harry, Ron, Hermione, and John all launched into an explanation about the Deathday Party. Castiel let them talk and focused his attention on tracing the patterns on the stone floor.

'But why not join the feast afterwards? Why go up that corridor?'

'Because-because-'

Castiel could tell he was struggling to find an answer that didn't have anything to do with the voice he'd heard.

'Because we were tired and wanted to go to bed,' Harry said.

'Without any supper?' said Snape. 'I didn't think ghosts provided food fit for living people at their parties.'

'We weren't hungry,' said Ron loudly, as his stomach gave a huge rumble.

'I suggest, Headmaster, that Potter and his friends aren't being entirely truthful, and I, for one, am quite interested in what Edlund has to say on the matter, given his talent for silence,' Snape said.

Castiel stiffened and glanced up at Dumbledore, then quickly looked back down at his feet. He opened his mouth to try to speak, but nothing made it past his furiously beating heart.

'Castiel,' Dumbledore said soothingly, 'do you agree with this version of events?'

Castiel nodded jerkily.

'There you have it, Severus,' Dumbledore said.

'As I say, Headmaster, I feel they are not being entirely truthful,' Snape continued, heedless of Castiel. 'It might be a good idea if they were deprived of certain privileges until they are ready to tell the whole story. Perhaps Potter should be taken off the Gryffindor Quidditch team, for instance, until he is ready to be honest.'

'Really, Severus,' said Professor McGonagall sharply, 'I see no reason to stop the boy playing Quidditch. The cat wasn't hit over the head with a broomstick. There is no evidence at all that Potter or any of his friends have done anything wrong.'

Castiel clenched his fists tightly, holding each breath as long as he could, hoping that no one would look at him if he made as little movement as possible. He heard Dumbledore speak softly, but firmly.

'Innocent until proven guilty, Severus.'

'My cat has been Petrified!' Filch shrieked, causing Castiel to squeak slightly and take a step back. 'I want to see some punishment!'

'We will be able to cure her, Argus,' Dumbledore said patiently. 'Madam Sprout recently managed to procure some Mandrakes. As soon as they have reached their full size, I will have a potion made that will revive Mrs Norris.'

'I'll make it,' Lockhart butted in. John cringed, almost able to hear what Sherlock would have said. 'I must have done it a hundred times, I could whip up a Mandrake Restorative Draught in my sleep-'

'Excuse me,' Snape said icily, 'but I believe that I am the Potions master at this school.'

There was a very awkward pause.

'You may go,' Dumbledore said to the five of them. They went as quickly as they could without actually running. As soon as they were outside, Castiel felt tears rush unbidden to his eyes and he dashed off before anyone could see them streaming down his cheeks.

The rest of them hurried away from Lockhart's office, picking up Sherlock from where he was waiting at the end of the corridor. Once they were a floor up, they turned into a classroom and closed the door quietly behind them.

'D'you think I should have told them about the voice I heard?' Harry asked Ron.

'No,' Ron and Sherlock said without hesitation.

'Hearing voices no one else can hear isn't a good sign, even in the wizarding world,' Ron explained. Something in his voice prompted Harry to ask, 'You do believe me, don't you?'

'Course I do,' Ron said quickly. 'But you must admit it's weird…'

'I know it's weird,' said Harry. 'The whole thing's weird. What was that writing on the wall about? The Chamber has been opened… What's that supposed to mean?'

'You know, it rings sort of a bell,' said Ron slowly. 'I think someone told me a story about a secret chamber at Hogwarts once… might've been Bill… Sherlock? Know anything?'

'I- it sounds familiar,' Sherlock said hesitantly. He was having difficulty concentrating on anything at all, though he was unlikely to admit it.

'And what on earth's a Squib?' said Harry.

Ron stifled a snigger and Sherlock smirked.

'Well- it's not funny really- but as it's Filch…' Ron said. 'A Squib is someone who was born into a wizarding family but hasn't got any magic powers. Kind of the opposite of Muggle-born wizards, but Squibs are quite unusual.'

'That would explain why he hates students so much,' John said.

A clock chimed somewhere.

'Midnight,' Harry said. 'We'd better get to bed before Snape comes along and tried to frame us for something else.'

'Are you going to check on Castiel before bed?' John asked Sherlock as they left the classroom.

'No, I'm sure he's fine. Madam Pomfrey wouldn't let me in the hospital wing at this hour anyway,' Sherlock said.

'Okay, well, goodnight then.'

'Goodnight.'

For a few days, the school could talk of little but the attack on Mrs Norris. Filch paced the spot she had been attacked, occasionally scrubbing at the message on the wall. He used bottles and bottles of 'Mrs Skower's All Purpose Magical Mess Remover', but to no avail, the words gleamed tauntingly at him as he stamped up and down the corridor, picking on unsuspecting students for things like 'breathing loudly' and 'looking happy'.

Ginny Weasley seemed very disturbed by Mrs Norris's fate. According to Ron, she was a great cat lover. She wasn't the only one affected. In the days since the attack, Castiel had refused to leave the hospital wing for anything but lessons, and he melted two cauldrons in one Potions lesson. Sherlock visited him the second night he was away from Ravenclaw tower, and caught him muttering to himself while making the beds.

'Seigneur, j'ai besoin de vous parce que je suis pleine de stress et d'anxiété. La lecture de votre mot apporte confort, que je vous demande de venir prendre mes lourdes charges-'

'You're religious, Castiel?' Sherlock interrupted. Castiel jumped and turned red.

'You speak French?' he mumbled, flattening a crease in the sheet in front of him. Sherlock shrugged. 'Yes, I am.'

'Does it make you feel any better?' Sherlock asked. Castiel hesitated, looking for signs of contempt on his face, but found only curiosity.

'It's comforting to know that someone is watching over you,' Castiel replied. 'My apologies, Sherlock, I know that Christians are not quite as common here as they are in the States, especially among wizards. Usually I pray silently,' he added hurriedly.

'No need to apologise. I don't understand it myself, but I don't mind if other people do. There's no point in badgering people about their religion when there are so many more interesting things to learn about.'

'Um.'

'Anyway, would you like some help with your Potions homework?'

The attack also had an effect on Hermione. It was quite usual for her to spend a lot of time reading, but she was now doing almost nothing else. John watched her from the table he and Sherlock spent most of their time sat at, sifting through newspapers, with several copies of Lockhart's books strewn about them. John found himself gazing at a familiar, faded headline. In fact, they had already gone through the entire stack. When he pointed this out, Sherlock stared at the newspaper and frowned.

'Are you sure? I don't remember seeing them,' he said.

'Yeah, I'm sure. I remember because you said that this man in the picture should try curling his hair if his intention was to look like a woman.'

'Oh. Yes.'

'Are you all right, Sherlock?' John asked, trying to peer past his thick hair.'

'Yes. Fine.'

He abruptly rose from the table and left John sitting alone with the newspapers.

Not long afterwards, Ron appeared and spread his homework across the table.

'What's that?' John asked him.

'History of Magic,' Ron said. 'Medieval Assembly of European wizards.'

John nodded. The one good thing about spending so much time in the library was that he got his homework done in good time. Ron took out a measuring tape and Harry arrived just as he let go of his parchment and it snapped back into a roll.

'I don't believe it, I'm still eight inches short,' he said furiously. 'Hermione's done four feet, seven inches, and her writing's tiny.'

John rested his chin on his hand and watched Harry unroll his own homework.

'Where is Hermione?' Harry asked.

'Somewhere over there,' John sad, waving a hand at the shelves, 'looking for another book. I think she's trying to read the whole library before Christmas.'

Ron frowned and bent over his essay and made his handwriting as large as possible to fill more space. Hermione emerged from between the bookshelves, looking irritable.

'All the copies of Hogwarts: A History have been taken out,' she said, sitting down next to John. 'And there's a two week waiting list. I wish I hadn't left my copy at home, but I couldn't fit it in my trunk with all the Lockhart books.'

'Why do you want it?' said Harry.

'The same reason everyone wants it, to read up on the legend of the Chamber of Secrets,' she said.

'What's that?' Harry asked.

'That's just it. I can't remember,' Hermione said, biting her lip.

I can't remember. The words echoed in John's head.

'Does Sherlock seem a bit off to you lately?' he asked suddenly. Ron shrugged.

'He's always like that,' he said.

'Mmm.'

'Hermione, let me read your composition,' Ron said desperately, checking his watch.

'No, I won't,' Hermione said, suddenly severe. 'You've had ten days to finish it.'

'I only need another two inches, go on…'

'Here, take mine,' John said, handing over his roll of parchment distractedly. Ron rushed to finish his work and gave it back just as the bell rang. Ron and Hermione led the way to History of Magic bickering.

John sat in his usual seat beside Hermione and concentrated on what she was writing instead of Professor Binns talking. He found that this stopped him from falling asleep during the lesson.

Today was as boring as ever. Professor Binns opened his notes and began to read in a flat drone like an old vacuum cleaner, until nearly everyone in the class was in a deep stupor. He had been speaking for half an hour when something happened that had never happened before. Hermione put her hand up.

Professor Binns stopped in the middle of his lecture, looking amazed.

'Miss-er-?'

'Granger, Professor. I was wondering if you could tell us anything about the Chamber of Secrets,' Hermione said in a clear voice.

John lifted his head away from his hand to look at her and revealed a nice, red handprint across his cheek.

Professor Binns blinked.

'My subject is History of Magic,' he said in his dry, wheezy voice. 'I deal in fact, Miss Granger, not myths and legends.'

He cleared his throat and continued his lecture, stuttering to a halt at Hermione's hand waving in the air again.

'Miss Grant?'

'Please, sir, don't legends always have a basis in fact?'

Professor Binns was looking at her in such amazement, John was sure no student had interrupted him before.

'Well,' Professor Binns said slowly, 'one could argue that, I suppose.' He peered at Hermione as though he had never seen a student properly before. 'However, the legend of which you speak is such a very sensational, even ludicrous tale…'

But the whole class were now hanging on Professor Binns' every word. He looked dimly at them all, every face turned to his. He was completely thrown by such an unusual show of interest.

'Oh, very well,' he said slowly. 'Let me see… the Chamber of Secrets…

'You all know, of course, that Hogwarts was founded over a thousand years ago by the greatest witches and wizards of the age. The four school houses are named after them: Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw, and Salazar Slytherin. They built this castle far from prying Muggle eyes, in a time when magic was feared and hated by common people.'

He paused to gaze blearily around the room. John glanced sideways at Hermione and saw that she was listening so intently that she wasn't even taking notes.

'For a few years, the founders worked in harmony together, seeking out youngsters that showed signs of magic and bringing them to the castle to be educated. But then disagreements sprang up between them. A rift began to grow between Slytherin and the others. Slytherin wished to be more selective about the students admitted to Hogwarts.

'Shocker,' Ron muttered.

'He believed that magical learning should be kept within all-magic families. He disliked taking students of Muggle parentage, believing them to be untrustworthy. After a while, there was a serious argument on the subject between Gryffindor and Slytherin, and Slytherin left the school.'

Professor Binns paused again.

'Reliable historical sources tell us this much,' he said, 'but those facts have been obscured by the fanciful legend of the Chamber of Secrets. The story goes that Slytherin had built a hidden chamber in the castle, of which the other founders knew nothing.

'Slytherin, according to the legend, sealed the Chamber of Secrets so that none would be able to open it until his own true heir arrived at the school. The heir alone would be able to unseal the Chamber of Secrets, unleash the horror within, and use it to purge the school of all who were unworthy to study magic.

John shivered violently and smashed his elbow painfully against the table. He suppressed a groan and rubbed it vigorously. No one took any notice of him and continued to watch Professor Binns, hoping for more. He, however, looked faintly annoyed.

'The whole thing is arrant nonsense of course,' he said. 'Naturally, the school has been searched for evidence of such a chamber, many times, by the most learned witches and wizards. It does not exist. A tale told to frighten the gullible.'

Hermione's hand was back in the air.

'Sir- what exactly do you mean by the 'horror within' the Chamber?'

'That is believed to be some sort of monster, which the heir of Slytherin alone can control,' said Professor Binns.

The class exchanged nervous looks and John shivered again, this time avoiding hitting his limbs on anything solid.

'I tell you, the thing does not exist,' said Professor Binns. 'There is no Chamber and no monster.'

'But, sir,' Seamus Finnegan said from across the room, 'if the Chamber can only be opened by Slytherin's true heir, no one else would be able to find it, would they?'

'Nonsense, O'Flaherty,' said Professor Binns in an aggravated tone. 'If a long succession of Hogwarts headmasters and headmistresses haven't found the thing-'

'But, Professor,' Parvati Patil piped up, 'you'd probably have to use Dark Magic to open it-'

'Just because a wizard doesn't use Dark Magic, doesn't mean he can't, Miss Pennyfeather,' snapped Professor Binns. 'I repeat, if the likes of Dumbledore-'

'But maybe you've got to be related to Slytherin, so Dumbledore couldn't-' began Dean Thomas, but Professor Binns had had enough.

'That will do,' he said sharply. 'It is a myth! It does not exist! There is no shred of evidence that Slytherin ever built so much as a secret broom cupboard! I regret telling you such a foolish story. We will return, if you please, to history, to solid, verifiable fact!'

And within five minutes, the class had sunk back into its usual torpor.

'I always knew Salazar Slytherin was a twisted old loony,' Ron told them, as they fought their way through teeming corridors at the end of the lesson to drop off their bags before dinner.

'Why's that?' Sherlock said, appearing behind them. Castiel pushed past them and disappeared down the corridor.

'Professor Binns just told us the legend of the Chamber of Secrets,' Hermione explained.

'Well, I could have told you that,' Sherlock frowned.

'But we asked you and you said you didn't know,' John said suspiciously.

'Oh.'

He didn't speak for moment while they were being squashed by other students.

'Is your elbow all right?'

'My elbow?' John said, rubbing the bruise. 'It's fine- how did you know?'

'Seamus told me you hit it on a table. Are you sure you're all right, you look pale.'

John's eyebrows shot up.

'Sherlock, I'm fine, and actually, I'm not pale, that's you. Maybe you should go to the hospital wing.'

'No, no, I'm all right.'

They were shunted along in the throng and Colin Creevey went past.

'Hiya, Harry!'

'Hullo, Colin,' Harry said automatically.

'Harry- Harry- a boy in my class has been saying you're-'

But Colin was so small he couldn't fight against the tide of people bearing him towards the Great Hall. They heard him squeak, 'See you, Harry!' and he was gone.

'What's a boy in his class saying about you?' Hermione wondered.

'That Harry's the heir of Slytherin, I expect,' John said.

'People here'll believe anything,' said Ron in disgust.

The crowd thinned and they were able to climb the next staircase without difficulty.

'D'you really think there's a Chamber of Secrets?' Ron asked Hermione.

'I don't know,' she said, frowning. 'Dumbledore couldn't cure Mrs Norris, and that makes me think that whatever attacked her might not be- well- human.'

'Well of course it's not human. No human has that sort of power,' Sherlock said. 'The only thing I can think of that does is a Gorgon, and I very much doubt we have one of those running around the castle.'

As he spoke, they turned a corner and found themselves at the end of the very corridor where the attack had happened. The corridor itself was now deserted, except for the silhouette of Castiel standing against a wall, staring at his feet.

'What are you doing up here?' John asked him.

'I- I was supposed to meet Gabriel here, but he hasn't come,' looking up slightly.

Filch ad left an empty chair against the wall bearing the message 'The Chamber has been opened.'

'Mr Filch went for dinner,' Castiel told them. Harry looked around at the others.

'Can't hurt to have a poke around,' he said, dropping his bag and getting on his hands and knees, searching for clues.

'Scorch marks!' he said. 'Here- and here-'

'Ah, yes, those were me. Unfortunate accident with a levitating torch,' Sherlock said. Harry rolled his eyes and stood up again.

'Come and look at this!' said Hermione. 'This is funny…'

They crossed to the window next to the message on the wall. Hermione was pointing at the topmost pane, where around twenty spiders were scuttling, apparently fighting to get through a small crack in the glass. A long, silvery thread was dangling like a rope, as though they had all climbed it in their hurry to get outside.

'Have you ever seen spiders act like that?' said Hermione wonderingly.

'No,' said Harry.

'He's afraid of spiders,' Sherlock smirked. 'Fred once turned his teddy bear into a spider.'

'Oh, you think it's funny, do you, Mr I-Can't-Fly-A-Broom,' Ron said hotly.

'Totally different. A broom can kill you. Heights can kill you.'

'Spiders can kill you!'

'Not in this country.'

'Oh, please, stop!' John said exasperatedly.

'Remember all that water on the floor?' Harry said, hurriedly changing the subject. 'Where did it come from? Someone's mopped it up.'

'It was about here,' Ron said, walking a few paces past Filch's chair and pointing. 'Level with this door.'

He reached for the brass doorknob but suddenly withdrew his hand as though he'd been burned.

'What's the matter?' said Harry.

'Can't go in there,' Ron said gruffly, 'that's a girls' toilet.'

'Oh, for goodness' sake,' Sherlock said. He moved past Ron, opened the door and walked in without hesitation.

'Don't worry, Ron, no one will be in there. It's Moaning Myrtle's bathroom,' Hermione said.

She too opened the door and followed Sherlock in. Castiel hung back for a moment, bouncing from foot to foot before finally going in himself.

Sherlock was already examining the basins and Hermione was tiptoeing towards the end cubicle. When she reached it she said, 'Hello, Myrtle, how are you?'

The boys went to look and saw Moaning Myrtle floating on the cistern of the toilet, picking at a spot on her chin.

'This is a girls' bathroom,' she said, eyeing them suspiciously. 'They're not girls.'

'We just wanted to have a look around,' Castiel said. Myrtle looked at him.

'You're American,' she said. 'There was an American boy in here the other day. Very handsome he was.'

'Ask her if she saw anything,' Harry mouthed at Hermione.

'What are you whispering?' said Myrtle, staring at him.

'Nothing,' Harry said quickly. 'We wanted to ask-'

'I wish people would stop talking behind my back!' said Myrtle, in a voice choked with tears. 'I do have feelings, you know, even if I am dead.'

'Myrtle, no one wants to upset you,' John said. 'Harry only-'

'No one wants to upset me! That's a good one!' howled Myrtle. Sherlock opened his mouth and John elbowed him.

'Say nothing,' he hissed, remembering the last time Sherlock was in the same room as Moaning Myrtle.

'My life was nothing but misery at this place and now people come along ruining my death!'

'We wanted to ask you if you'd seen anything funny lately,' Hermione said quickly, 'because a cat was attacked right outside your front door on Hallowe'en.'

'Did you see anyone near here that night?' asked Harry.

'I wasn't paying attention,' Myrtle said dramatically. 'Peeves upset me so much I came in here and tried to kill myself. Then, of course I remembered that I'm- that I'm-'

'Already dead,' Ron said helpfully.

Myrtle gave a tragic sob, rose up in the air, turned over and dived head first into the toilet, splashing water all over them and vanishing from sight. From the direction of her muffled sobs, she had come to rest somewhere in the U-bend.

Hermione sighed wearily.

'Honestly, that was almost cheerful for Myrtle… come on, let's go.'

They had barely gotten out of the door when a loud voice made all six of them jump.

'RON!'

Percy Weasley had stopped dead at the head of the stairs.

'That's a girls' bathroom!' he gasped. 'What were you-?'

'What's going on?' another voice from behind Percy said. Gabriel stepped up beside Percy and grinned at Castiel.

'I just found them coming out of the girls' bathroom,' Percy told him.

'Oh, yeah? Looking for clues? Doing the detective bit I bet,' Gabriel said. 'Hey, little brother, sorry I'm late. I accidentally transfigured a guy's nose into a carrot. McGonagall did not find it quite as amusing as I did. Find anything good in there? Besides Moaning Myrtle, I mean.'

Castiel shook his head.

'Get- away- from- there-' Percy said, striding towards them, flapping his arms.

'Hey, relax, it's not like this is the first time they've been in the girls' bathroom, am I right?' Gabriel joked, following him down the corridor. Percy turned to glare at him.

'Why on earth Dumbledore made you a Prefect, I'll never know,' he spat angrily.

'Okay, rude.'

'Don't you care what this looks like?' Percy said to Ron. 'Coming back here while everyone's at dinner…'

'Why shouldn't we be here,' Ron said hotly. 'Listen, we never laid a finger on that cat!'

'That's what I told Ginny,' Percy said fiercely, 'but she still seems to think you're going to be expelled. I've never seen her so upset, crying her eyes out. You might think of her, all the first-years are thoroughly over-excited about this business-'

'You don't care about Ginny,' said Ron, whose ears were reddening now. 'You're just worried I'm going to mess up your chances of being Head Boy.'

Castiel slowly backed away from the raised voices and Gabriel, seeing the small movement, stepped between the two Weasley brothers.

'Ok, that's enough!' he said sternly. 'Everyone just calm down. Do you really think yelling at each other is solving anything? Geez, the British are high strung.'

Percy and Ron glared coldly at each other for another moment.

'Five points from Gryffindor!' Percy said tersely, fingering his Prefect badge. 'And I hope it teaches you a lesson! No more detective work, or I'll write to Mum!'

And he strode off, the back of his neck as red as Ron's ears.

Gabriel slung an arm around Castiel's shoulders.

'Come on, kid, Hagrid's waiting for us,' he said.

'He is?'

'Yeah, we're going for dinner. And he picked out a nice spot where you can plant those apple trees, too.'

The rest of them, minus Castiel, headed back to the Gryffindor common room, sitting as far away from Percy as possible, and setting out their Charms homework. Sherlock and John practiced origami with scraps of parchment, having finished their homework already. Ron was still in a foul mood and kept blotting his parchment, and when he reached for his wand to clear it, he accidentally ignited it. Fuming almost as much as his homework, Ron slammed The Standard Book of Spells, Grade 2 shut. To their surprise, so did Hermione.

'Who can it be, though?' she said in a quiet voice. 'Who'd want all the Squibs and Muggle-borns out of Hogwarts?'

'Let's think,' Ron said in mock puzzlement. 'Who do we know who thinks Muggle-borns are scum?'

He looked at Hermione. Hermione looked back, unconvinced.

'If you're talking about Malfoy-'

'Of course I am!' said Ron. 'You heard him: "You'll be next, Mudbloods!". Come on, you've only got to look at his foul rat face to know it's him-'

'Malfoy, the heir of Slytherin?' said Hermione sceptically.

'Look at his family,' said Harry, closing his books too. 'The whole lot of them have been in Slytherin, he's always boasting about it. They could easily be Slytherin's descendants.'

'Don't be ridiculous,' Sherlock said. 'Just because they're in Slytherin, doesn't mean they're descendants of him. My family have all been in Ravenclaw, and we're not descended from her. Nor are the Weasleys descended from Gryffindor.'

'Sherlock's right,' John said, holding up a lopsided paper bird. 'Malfoy's not the most pleasant person around, but he's not likely to be Slytherin's heir. I mean, can any of you honestly see him killing anyone? Because I don't.'

'Why do you have to disagree with everything?' Ron said exasperatedly.

'Because, Ron, you like to pin things on people you don't like without even thinking about it. Remember Snape last year?'

Sherlock gave John a searching look.

'Even still, Harry's got a point. It's not very likely, but it is still possible,' Hermione said reasonably.

'But how do we prove it?' Harry said.

'There might be a way,' Hermione said slowly, glancing at Sherlock. 'Of course, it would be difficult. And dangerous, very dangerous. We'd be breaking about fifty school rules, I expect.'

John snorted.

'That's different. So, come on, what is it?' he said.

'Well, what we'd need to do is get inside the Slytherin common room and ask Malfoy a few questions without him realising it's us.'

Sherlock smiled at her.

'That sounds like an excellent idea,' he said.

Harry and Ron exchanged confused looks and John rolled his eyes.

'He means, he knows what she's talking about and they're doing that thing where they assume we know too, but we don't. So, care to explain?'

'Polyjuice Potion,' Hermione and Sherlock said in unison.

'Are we supposed to know what that is?' John said.

'Snape mentioned it in class a few weeks ago-'

'Do you think we've got nothing better to do in Potions than listen to Snape?' Ron muttered.

'It transforms you into someone else. Think about it! We could change into Slytherins. No one would know it was us. Malfoy would tell us anything.'

'This Polyjuice stuff sounds a bit dodgy to me,' Ron frowned. 'What if we got stuck looking like Slytherins forever?'

'It wears off,' Sherlock said impatiently.

'Yes, but getting the recipe will be very difficult. Snape said it was in a book called Moste Potente Potions and it's bound to be in the Restricted Section of the library.'

There was only one way to get a book out of the Restricted Section: you needed a signed note from a teacher.

'Hard to see why we'd want the book, really,' said Ron, 'if we weren't going to try and make one of the potions.'

'I think,' said Hermione, 'that if we made it sound as though we were just interested in the theory we might stand a chance…'

'Oh, come on, no teacher's going to fall for that,' said Ron. 'They'd have to be really thick…'

Hello again everyone :) I finished college a couple weeks ago so I will definitely have more time to write now, so that's good.

Thank you to purrlock, Reichenbach-Hero, Trapped under Loki's spell, Maliha, FaroreWorldshaper, puffypuffin3, Potter4life01 and Featherfur for the reviews :) you guys are great and I love you.

As always, this chapter will shortly be posted on AO3.