The Polyjuice Potion

'Nice of you to turn up,' John huffed as Sherlock finally ambled into the hospital wing.

John and Justin had both been carried up to the hospital wing on stretchers by Professor Flitwick and the Astronomy teacher, Professor Sinistra. The lessons for the rest of that day had been cancelled and Professor McGonagall had begun marching around the corridors in an attempt to reign in the chaos caused by the double attack.

'Where have you been? I was looking for you,' John said.

Castiel had been put in charge of looking after John while Madam Pomfrey found a place for Justin and Nearly-Headless Nick. This wasn't easy as it was impossible to lay Nick on a bed. In the end, she settled for wafting him into a corner and conjured high curtains around him.

'I was- I was-'

'You were talking to Professor Lockhart, right?' John prompted.

Castiel clinked around, peering at different potions, trying to work out which ones would work on John; having already given him all the usual ones.

'-Yes, I was talking to Professor Lockhart,' Sherlock said uncertainly.

'Why?'

Castiel pressed a cold flannel to John's forehead and gave him a phial of purple potion. He accepted it and swallowed a mouthful. It tasted like ice and John shuddered. Castiel watched him closely for about a minute, then frowned. Evidently it had not done what he was expecting it to do.

'I can't give you any more potions,' he said. 'They might start to react badly with each other.'

'Why isn't it working?' Sherlock asked.

'I- I have to talk to Madam Pomfrey,' he stuttered, scuttling away.

John fell back against his pillows, feeling very tired now.

'You have to go home,' Sherlock said, looking at John. 'That could have been you.'

'I'm going home for Christmas. I'm fine.'

'It was very close, John. I want you to stay there.'

'You're not serious,' John laughed. Sherlock said nothing. 'No. Absolutely not.'

'You're not safe here.'

'So? Neither's anyone else. What're you going to do, send all the Muggle-borns home?'

Sherlock opened his mouth, but he was interrupted by Ron and Hermione hurrying up to them, closely followed by Molly Hooper. Castiel was suddenly there too, taking advantage of the distraction to garb Sherlock's arm and pull him away.

'What? What's wrong?' Sherlock asked.

'The only reason those potions wouldn't work is if it isn't a normal flu,' Castiel said.

'What do you mean?'

'We can't cure it because it's magical, and we don't know the cause.'

Sherlock stiffened.

'So he's been poisoned?'

Castiel fidgeted.

'Well…no. I don't think so. That last potion I gave him was meant to reveal any poisons in his system. It would have made him sneeze if there had been any.'

Sherlock stared at him, confused. He could hear the quiet murmur of voices behind him.

'So, what then?'

Castiel hesitated, then leaned in closer.

'I think it might have something to do with his being the Oracle,' he murmured. 'There's never been one before, so no one would know the exact symptoms, but a lot of Seers reported having mild flus before their powers had fully matured. It's magical and it's more severe because he's more powerful. It fits.'

'No it doesn't. We have that- er- thing. If it is that, why am I fine?'

Castiel scrutinised him.

'I don't think you are,' he said.

'What's that supposed to mean?' Sherlock demanded.

Castiel flinched and rubbed his arm.

'You've been- strange- lately. More so than usual. Like today. Normally, you'd be the first to know that John was so sick, but you've been missing all day,' he explained carefully.

Sherlock considered this and conceded.

'We're both going home for Christmas, so I'll make sure he gets to his mom safely. Unfortunately he's just going to have to wait this out,' Castiel said. He smiled slightly and went back to John to check his temperature again.

At last, the term ended and, in the panic following the attack, most of the school had signed up to go home. Castiel did as he said, making sure that John was all right and helped him on to the train.

A silence as deep as the snow descended on the castle and Harry, Hermione and the Weasleys had the run of Gryffindor Tower. Sherlock, the only Ravenclaw that had elected to stay, had been given permission to stay with the Gryffindors, and stared out of the window at the snow while the rest of them played Exploding Snap. Fred, George, and Ginny had chosen to stay at school rather than visit Bill in Egypt with Mr and Mrs Weasley. Percy, who disapproved of what he termed their childish behaviour, didn't spend much time in the Gryffindor common room. He already told them pompously that he was only staying over Christmas because it was his duty to support the teachers in this troubled time ('Not like that Gabriel. I don't know what he's thinking. So irresponsible.').

Sherlock didn't sleep Christmas Eve. Restless and irritated, he rose before the sun and was surprised to meet Hermione in the common room.

'Oh, good, you're up. Come help me with the potion, it's nearly ready,' she said briskly.

So up to Moaning Myrtle's bathroom they went.

Hermione settled in front of the cauldron and watched the potion like a hawk, adding a few lacewings every so often. Myrtle, who was in a particularly festive mood, only cried twice while they were there and even wished them a 'M-m-merry Christmas.'

After an hour, Hermione sat back from the cauldron.

'It's ready,' she said. 'Come on, let's go back. I want to wake Harry and Ron up.'

Harry and Ron had been sleeping peacefully until Hermione arrived.

'Wake up,' she said loudly, opening the curtains to let in the white winter light.

'You're not supposed to be in here,' Ron grumbled. Sherlock was surprised to find a small pile of presents had been delivered to the bed he'd been sleeping in.

'Merry Christmas to you too,' said Hermione, throwing Ron his present. 'Sherlock and I have been up for over an hour, adding more lacewings to the potion. It's ready.'

Harry sat up to look at her.

'Are you sure?' he said.

'Positive. If we're going to do it, I say it should be tonight.'

At that moment, Hedwig, Grace, and Greg, dropping in presents from the Dursleys, from Castiel, and from John.

Sherlock picked up the one from John first. The note attached to it said, 'Hope this helps. From John'. He tore off the packaging and chuckled at the familiar-looking box. Inside, a shiny, new Slytherin tie was folded neatly. Along with that, John had also gotten him, and everyone else, a pair of gloves. For snowball fights according to him.

From Castiel, everyone had received a small phial of Pepperup Potion that he had made himself, just in case. After seeing the effect it had had on Ginny earlier in the year, none of them were particularly keen to try it.

In his pile, Sherlock also found a gift from Mycroft that turned out to b a new set of scales, and a lumpy parcel from Mrs Weasley. It seemed that, he too, had been given a home-knitted jumper. It was a deep, indigo colour, and it had his initial on it.

'Mum made you a jumper?' Ron asked, staring at it.

'Your mum always makes me a jumper.'

In truth, he had never worn it, but, for some reason he couldn't place, this time was different. He pulled it on over his head and felt the warmth from it, and ate some of the plum cake that had come with it.

It was Sherlock and Hermione's first Christmas at Hogwarts and both of them were thoroughly enjoying themselves at Christmas dinner. Sherlock and the Weasley twins kept taking it in turns to steal Percy's Prefect badge, and bewitching it to say different things. Eventually Percy got it back, but he didn't notice that it now said 'Pinhead'.

Sherlock didn't eat much, and started to get bored waiting for everyone else to finish. Hermione too got impatient and ushered them out of the hall after Harry and Ron had finished their third helping of Christmas pudding.

'We still need a bit of the people you're changing into,' she said once they'd got out of the hall.

'I've got mine,' Sherlock said. He pulled a corked phial out of his pocket to show them the dark hairs that he had collected. 'I put a Full-Body Bind on the Slytherin boy I was paired with at the Duelling Club. Moriarty his name is. He went home, but he's a first-year so Malfoy won't notice if he's around.'

'But how are you going to question Malfoy if he doesn't know who you are?' Harry said.

'Well I thought about that. It'll look suspicious if four people question him at once, so I thought if I disguised myself as someone unnoticeable, I'd be able to search his dormitory while you three have him distracted.

'We've got it all worked out,' Hermione said smoothly. 'It would be best if you two got hairs from Crabbe and Goyle. They're his best friends, he'll tell them anything.'

'Because that'll be easy,' Ron said sarcastically.

'Actually, I think it will be. All we have to do is make sure that the real Crabbe and Goyle can't burst in on us while we're talking to Malfoy, so-' she held up two plump chocolate cakes '- I filled these with a simple Sleeping Draught. All you have to do is make sure Crabbe and Goyle find them. You know how greedy they are, they're bound to eat them. Once they're asleep, pull out a few of their hairs and hide them in a broom cupboard.'

'And remember to take their shoes. You'll need them,' Sherlock added. 'Hermione and I will go and get some spare robes from the laundry room and meet you back in the bathroom.'

They hurried off in separate directions, Sherlock and Hermione down to the laundry room. They quickly located some large robes that looked like they would fit Crabbe, Goyle, and Millicent Bulstrode. Then Sherlock grabbed some that were too small for him, but just right for Moriarty. He and Hermione sprinted back up to Moaning Myrtle's bathroom and put the robes beside the basin. Hermione dashed into the cubicle and stirred the potion until it began to bubble and smoke thick black clouds. She set out four glass tumblers and continued stirring the potion while they waited for Harry and Ron. Finally, they heard a soft knock on the door.

'Hermione? Sherlock?'

Harry and Ron came in and quickly shut the door behind them.

'Did you get them?' she asked breathlessly, wiping her forehead.

Harry held out the hairs and Ron held up the shoes.

'Good. The robes are over there,' she said, pointing at them. 'I'm sure I've done everything right.'

She nervously re-read the splotched page in Moste Potente Potions, then handed it to Sherlock. He re-read it and peered closely at the potion. It looked like thick, dark mud, bubbling sluggishly.

'It looks like it should,' he reassured her. 'Once we've drunk it, we'll have exactly one hour before we change back into ourselves.'

'Now what?' Ron asked nervously.

'We separate it into the glasses and add the hairs.'

Hermione ladled large dollops of the potion into each of the glasses. Then she shook Millicent Bulstrode's hair out of its bottle into the glass.

The potion hissed loudly like a boiling kettle and frothed madly. A second later, it had turned a sick sort of yellow.

'Eurgh- essence of Millicent Bulstrode,' said Ron, eyeing it with loathing. 'Bet it tastes disgusting.'

'Add yours, then,' Hermione said.

The three of them dropped the hairs into their glasses. They hissed and frothed: Goyle's turned the khaki colour of a bogey, Crabbe's a murky brown, and Moriarty's turned a dark, navy blue.

'Well yours doesn't look so bad,' Ron grumbled, looking at Sherlock's glass. Sherlock made a grunting noise and disappeared into a cubicle with his set of robes and his potion. He heard the others locking themselves in other cubicles.

'Ready?' Harry called.

'Ready,' he, Ron and Hermione said.

Sherlock downed his potion and shuddered. It tasted like overcooked cabbage.

Immediately, his insides started writhing, as though he'd just swallowed live snakes. He clutched at the sides of the cubicle, fighting to keep himself standing. A burning sensation spread to his fingers and his toes, but by far the worst part was the feeling that his skin was melting as it bubbled like hot wax. He watched as his fingers shrunk and the floor seemed to be coming towards him until he realised that his legs were getting shorter. His hair began to recede back into his scalp and for the first time in years he didn't have it in his eyes. His forehead felt oddly cold.

Suddenly, it was over. Everything stopped. Breathing hard, Sherlock examine himself carefully. His robes felt slightly tighter on the shoulders and they were dragging along the ground around his feet, and his shoes were now too big. He quickly changed into the Slytherin robes, then pulled a tie box out of his own, Ravenclaw ones. He smiled at the Slytherin tie as he lifted it out of the box and put it on for luck. Not that he believed I luck. He started at the sound of Goyle's low, rasping voice coming from his left.

'Is everyne okay?'

'Yeah,' came Crabbe's deep grunt.

'Yes,' Sherlock said. He was surprised to hear a rich, Irish accent issuing from his own mouth. He opened the door to his cubicle and came out to find himself face to face with Goyle. Well, more like face to chest.

Ron, too, emerged from his cubicle. Aside from looking pale and shocked, he was indistinguishable from Crabbe. Sherlock quickly glanced down at himself and was pleased to find that he looked exactly like Moriarty, and he smiled as he worked out that he was still taller than John.

'You have no idea how bizarre it is to see Goyle thinking,' Ron said to Harry in amazement. He banged on Hermione's door. 'C'mon, we need to go…'

'I-I don't think I'm going to come after all. You go on without me,' she answered in a high-pitched voice. Immediately, Sherlock knew something was wrong. Millicent Bulstrode's voice was anything but high-pitched.

'Hermione, we know Millicent Bulstrode's ugly, no one's going to know it's you,' Ron said.

'No – really – I don't think I'll come. You three hurry up, you're wasting time.'

'Hermione, are you ok?' Harry asked through the door.

'Fine – I'm fine… Go on – '

'She's right. We've already lost five minutes,' Sherlock said, blinking as he was once again caught by surprise at the accent.

Ron and Harry hesitated and Sherlock, getting bored, left without them, ending up having to wait for them in the Entrance Hall once he remembered that they didn't know where the Slytherin common room was.

'Patience is a virtue, you know,' Ron grumbled as they caught up. Sherlock rolled his eyes and motioned with a finger for them to follow. He led them down into the dungeons, passing a Ravenclaw girl with long curly hair in the damp corridor. Concentrating on remembering his way through the labyrinthine passages, he barely noticed a figure emerging from a side room.

'What're you doing down here?' said Ron in surprise.

It was Percy.

'That is none of your business,' Percy said stiffly. 'It's Crabbe, isn't it?'

Sherlock melted away, unseen by Percy, and continued on to the entrance of the Slytherin common room, smiling slightly as he passed Draco Malfoy in the corridor. He knew that he would let the other two in once he found them. Sherlock whispered 'Pure-blood' to the bare stone wall and it slid open. It was just as he remembered it. The rough, stone walls, the green lamps, and the ebony furniture. As he'd thought, no one noticed him come in. He quickly strode over to the dormitories, but instead of going through the left door into the girls' dormitories, as he had done last year, he went right into the boys'. Sherlock looked around the long stone corridor with seven doors along it, identical to the one he'd been in, and entered the second door along, where the second-year boys slept, Malfoy's bed was in the centre of the room, his bedside table littered with sweet wrappers. There was a copy of the Daily Prophet lying on the bed, the front page facing up. Sherlock snatched it up and quickly read the article.

ENQUIRY AT THE MINISTRY OF MAGIC

Arthur Weasley, Head of the Misuse of Muggle Artefacts Office, was today fined fifty Galleons for bewitching a Muggle car.

Mr Lucius Malfoy, a governor of Hogwarts School of Witchcraft and Wizardry, where the enchanted car crashed earlier this year, called today for Mr Weasley's resignation.

'Weasley has brought the Ministry into dispute,' Mr Malfoy told our reporter. 'He is clearly unfit to draw up our laws and his ridiculous Muggle Protection Act should be scrapped immediately.'

Mr Weasley was unavailable for comment, although his wife told reporters to clear off or she'd set the family ghoul on them.

Sherlock heard footsteps tapping against the stone outside, threw the paper back down on the bed, and quickly hid in one of the other beds, drawing the curtains. He peeked through a gap in the fabric and watched Malfoy grab the newspaper and leave hurriedly. Once he was gone, Sherlock left his hiding place and started rummaging through Malfoy's things, looking for anything that might connect him to the heir of Slytherin, or at least rule him out. Finally, he found a letter in the top drawer of the bedside table. He flipped it open and was disappointed by what he read.

Draco

Try to understand that it will be suspicious if you know too much about the heir. It was before my time, but, yes, you're right I do know something about it. There is no way that you can help except by keeping your head down and letting them get on with it. The last time this happened, the heir was left unimpeded and a Mudblood was killed. Heaven knows that school of yours needs ridding of that filth so you'd better leave well enough alone, and try not to draw any more attention to yourself, we don't need any more raids. We will see you in the summer.

Your Father.

Sherlock pursed his lips and put the letter back the way he had found it. It didn't prove anything, but at least they could rule one person out. He walked back to the common room and found himself looking at the back of Malfoy's head.

'Luckily, we've got our own secret chamber under the drawing room floor-' Malfoy was saying.

Harry and Ron were sitting opposite him.

Ron's – or rather Crabbe's – face lit up with excitement.

'Ho!' he said loudly.

Malfoy looked at him. So did Harry, and Sherlock's eyes widened as Crabbe's face turned red, and then so did his hair. Sherlock realised that they were turning back into themselves and his hand shot up to his head, where he felt his hair starting to curl beneath his fingers.

Harry and Ron both jumped to their feet, mumbling something about medicine. They sprinted the length of the common room, hurled themselves at the stone wall and disappeared up the passage. Sherlock walked around Malfoy, who paid no attention to him, and followed them out.

They'd already dashed up to Myrtle's bathroom, so Sherlock continued on his way and met them up there. By the time he arrived, he had turned back to normal, the trousers of his stolen robes hanging around his calves. Harry and Ron had also returned to normal and were changing their robes. Ron hastily pulled his own cloak over his head and hammered on the door of Hermione's cubicle.

'Hermione, come out, we've got loads to tell you –'

'Go away,' Hermione squeaked.

Sherlock's stomach sank.

'What's the matter?' said Ron. 'You must be back to normal by now…'

But Moaning Myrtle suddenly glided through the cubicle door. She had never looked so happy.

'Ooooh, wait till you see,' she said. 'It's awful!'

The lock slid back and Hermione emerged with her robes pulled up over her head.

'What, have you still got Millicent's nose or something?'

Hermione let her robes fall. Her face was covered in black fur. Her eyes had turned yellow and there were long ears poking through her hair.

'It was a c-cat hair!' she sobbed. 'M-Millicent Bulstrode m-must have a cat! And the Potion isn't supposed to be used for animal transformations!'

'Uh oh,' said Ron.

'You'll be teased something dreadful,' Myrtle said happily.

'It's okay, Hermione,' Harry said quickly. 'We'll take you up to Madam Pomfrey.'

'Yeah, Madam Pomfrey never asks too many questions. Never said anything even though she knew I as lying about Norbert biting me,' Ron assured.

It took a while for them to persuade Hermione to leave the bathroom. Myrtle sped them on with a gleeful comment,

'Wait till everyone finds out you've got a tail!'

Thanks to LunaEtSidera, Reichenbach-Hero, fastreader12, maliha1205, CoolNinjaofDoom, TsubasaKEI, SeanHicks4, and ChuitoReyes for the reviews.

I realise that it's been quite a gap since I posted the last chapter, and I am really sorry about that. I've had a lot going on but, as I said, I would like to complete the series and still plan on doing so, although it may take me a while. I write whenever I can, if only for a few minutes so I am still going. Thanks to those that are still around and I hope to see you soon.