So wow, 17 was a popular chapter! Thanks everyone who started following/favourited.The Lady Enchantress, I hope you read past chapter 3! (Just kidding, thanks for your review) and HikariTatami, don't worry, updates are usually 2x a week (hopefully it will stay that way).iwantsprezzatura, FromEyesToMind, HT188, creelluka and xXRosexScorpiusXx you guys are the best, I look forward to hearing your thoughts on the rest of the Polyjuice escapade!

Without further ado...

'Nobody trusts me in this world,' James grumbled to Sirius as they walked to the dungeons, having had strict instructions on how to get to the Slytherin common room.

It had been decided that Sirius and James would go and sleep in the Prefect's bathroom, saying that Regulus and Emma had Prefect duty. When Sirius had joked that it made it sound like they were going to hook up, he was silenced by three cold stares, but James suggested that Sirius stay in the Slytherin dorms instead - an idea that everyone but Sirius liked.

'It's a hard life Prongs,' Sirius patted his shoulder. 'But don't worry, I still love you.'

'You do?' James looked at him with big puppy dog eyes.

'Okay, I can't do this when you look like your sister,' Sirius immediately withdrew his hand. 'No offense man, but it both turns me on and weirds me out.'

'Too much information Padfoot,' James shuddered. 'Why is it weird anyway? It's not like Emma and I have really different facial expressions. Not like you and your brother.'

'So firstly, that twit is not my brother,' Sirius ticked off his finger. 'And secondly, have you seen how she looks at me? I swear, even a piece of dog poo she found on her shoe would command more respect.'

'What a wonderful metaphor Padfoot,' he commented dryly. 'But why would she do that?'

'Um hello? My brother's poisoned her against me!' Sirius said in a dramatic manner. 'But seriously, maybe I shouldn't have come to yours this summer.'

'Are you kidding? My parents love you!'

'Maybe that's the problem.'

James didn't have an answer for that, especially since Sirius hadn't made his "serious" joke, so he changed the subject. 'Do you know the Slytherin password?'

'Probably "Pure-blood" or something,' Sirius muttered, still brooding.

A couple of hours later, Lestrange returned from the Hospital wing to see the two slouching in front of the alcove. Sirius had gotten himself comfortable between the two pillars, whereas James had adopted the sleep-where-you-stand method. Both started at the sudden darkness that his shadow cast on the entrance.

'Great,' Sirius said under his breath. 'Why couldn't it have been Reggie's admirer?'

'Remember, we're not us,' James whispered. 'If he suspected it was...'

'We'd have the whole Slytherin common room on us, yeah, yeah, I'm not an idiot,' Sirius said in a bored voice.

'Why are you two hanging around here?' Lestrange asked as he came nearer.

'Forgot the password,' James said with what he hoped was an innocuous shrug.

'Both of you?' he asked incredulously, a surprised grin forming on his face.

'Yeah it's very funny, now let us in,' Sirius said, rolling her eyes.

'Well someone's in a bad mood,' Lestrange raised his eyebrows. 'Locomotor Wibbly.'

The Jelly-Legs jinx? James bit back a laugh.

'You would be too, if you were stuck in your bloody brother's body for the day,' Sirius retorted.

'Excuse me? I was a Mudblood. On top of that, your bloody brother as you put it hexed me,' Lestrange said heatedly.

'And you just let it happen?' James feigned shock.

'A Mudblood girl against the entire Slytherin crew? You've got to be joking. I'll get back at him some other day. Now if you don't mind, I have some robes to burn.'

He strode off down the steps, Sirius and James hurrying after him. The latter couldn't resist nudging his friend and teasing him. 'Ooh, better watch your back now Lestrange is onto you.'

'Shut up,' was the answer, but Sirius chuckled all the same.

Inside the common room, the Slytherin sixth and seventh years were already doing work, whilst a group of fifth years played Exploding Snap in a corner. They looked around interestedly at the green light and black leather armchairs.

'Civilised, isn't it?' Sirius muttered. 'I was expecting skulls or at least torture chains.'

'Come on you two!' Emma's redheaded friend called them over to the fireplace. 'Anyone would think you'd never seen the common room before.'

'They couldn't remember the passwords either,' Lestrange chuckled. 'I think the fumes from Potions class Confunded them.'

'I saved you a spot Regulus,' a fourth-year called out.

'Don't tell me my brother's gay?' Sirius said in a joyful undertone to James. 'Oh I bet dear old Mum would love that: a blood-traitor blasted off the family tapestry, and the proper little son incapable of providing an heir. She'd die from the shame.'

They went and slumped on the sofa, which was surprisingly comfortable. Act as if this was Gryffindor, James told himself. At least they have squishy furniture. Another surprise to them was that the Slytherins talked of normal things. Quidditch: a question about the captaincy that James deflected easily, complaining about homework, asking each other about their OWLs and subjects they dropped, talking about Zonko's joke shop. Regulus's tag-along was Barty Crouch's son, to James's surprise. When James commented that he didn't look like his father, the kid looked at him with shining eyes, and James thought that he might have made Emma a new friend. When Alecto Carrow yawned and said she was going to turn in for the night, James had hardly noticed the time fly.

'Merlin!' he said theatrically, jumping up. 'I forgot I was supposed to do the rounds tonight, show the new fifth years how it works.'

'Bit late for that Potter,' Mulciber said. 'They left half an hour ago.'

Perfect, James thought, climbing the stairs to the exit. I hope Sirius survives the night.

'Hey Emma,' Wilkes, one of Snivellus's gang had followed her.

James pretended not to have heard him, but the Slytherin caught up with him outside the secret entrance.

'Emma have you got a sec?' Wilkes asked. 'I was wondering. I mean I know it's early and everything, but do you want to go to Hogsmeade with me? On the weekend when it's posted I mean.'

'No!' James said, horrified at the thought of Emma being with one of Snivellus's cronies. Wilkes took a step back, and James realised that he was acting like the brother. 'It's just I've got a lot of Prefect duties, and I'm team captain - we might have tryouts or something.'

'Well maybe another time,' Wilkes started.

'No, I think I'm busy all the time. Every weekend until the end of the year. And maybe the year after that,' James said definitely, and fled for the Prefect's bathroom.

'So I guess we should make our way to the Gryffindor tower then,' Regulus said reluctantly.

'No way,' Emma replied. They were dawdling in the Great Hall, wondering how long it would take for Remus Lupin and Peter Pettigrew to fall asleep. The excuse was that they were planning a great prank, but Lupin had looked at Emma knowingly and mouthed: I know it's about Lily. 'If I'm going to be stuck as my brother the rule breaker, then we should enjoy it as much as we can.'

'What are you saying?' Regulus asked, a hint of a smile playing on his... Sirius's... face.

'I missed your birthday,' Emma reminded him. She still felt guilty about that. She could only imagine what had happened during the Sirius/Walburga fight. 'I thought you were on holiday with your family or something, and that was why you never replied to my letters.'

'I replied to all of them,' Regulus protested.

'I know that now, don't I?' Emma said, rummaging in her bag before a thought struck her. 'Do you realise that we all kept our own schoolbags? I wonder if anyone noticed.'

'Doubt it,' he made a face. 'What are you looking for?'

'Something that I haven't told anyone about,' she said enigmatically, enjoying the look on Regulus's face. It wasn't often that he didn't know about something. 'Ah here it is!'

'A cloak?' Regulus asked dubiously. 'If you wanted a warmer one, you should have asked James when you had the chance.'

'Not just any cloak,' she said. 'Come here.'

He cautiously took a step closer and she threw the cloak over the both of them. Merlin knows how James and Sirius can sneak around in this thing. It barely reaches his ankles! But Regulus was more preoccupied about the nature of their dad's Hogwarts gift.

'You have an Invisibility Cloak?' he gasped. 'And you didn't tell me?'

'I was going to in fifth year, but I guess I just never got around to it. We were Prefects, and there wasn't much point. Remember when I asked you about liking secrets? Besides, it's not as if we sneak around much, do we? We just go down to the Quidditch pitch.'

The dungeons weren't too far from the Great Hall and since their first excursion down to the clearing in the Forbidden Forest, they had become adept at sneaking out into the grounds. They soon found out that no one ever surveyed the Quidditch pitch - after all, they turned a blind eye to players wanting to get in a last bit of practice before the game the next day.

'I guess you have a point,' he conceded.

She led him up to the Entrance Hall and then down to the basement level again, coming to a stop in front of a painting of a bowl of fruit.

'You brought me down here to look at pictures of food?'

She ignored him, tickling the pear until it turned into a doorknob, wrenching it open. The little entrance grew larger and larger, until it seemed like it had been human-sized all along.

'Master James! Master Sirius!' A cheerful elf came bounding up to them. 'Do you want the usual?'

Emma had no idea what the usual was. 'Actually...' she realised that she didn't know what Regulus liked. 'Regulus?'

'Banoffee pie,' Regulus grinned.

He didn't seem too surprised at the fact that the Hogwarts kitchens seemed to be run solely by house elves, maybe because Kreacher was the one to do all the cooking in the Black family household. Either way, he seemed excited to be there, examining pots and pans here and there, even going to stop a few house elves to ask them their name and tell them which foods he liked best.

Emma watched him incredulously. Though she knew he was friendly with Kreacher, she had expected his favourite food to be something fancy, like chocolate gateau, or treacle tart.

'What?' Regulus asked, noticing her stare. Sirius's face tinged red.

'I don't think I've ever seen you blush before,' Emma said, smiling. 'Unless you count the singing rose.'

'Technically you still haven't,' and in the blink of an eye Sirius was serious again. He sat down on one of the long benches. 'Urgh, these Gryffindor robes.'

'They're not that bad,' Emma sat next to him. 'It's only the tie and the crest that changes, really. Oh and the colour of the insides.'

'Yeah, but these even smell like Sirius,' Regulus said in disgust.

'What smell is that?' Emma laughed.

'Like wet dog and gunpowder.'

'What?'

He proffered a sleeve and Emma sniffed it. The worst part is that he's right, she thought.

'Odd,' she said, but by that time a huge banoffee pie had arrived. She conjured a couple of candles and lit them with her wand. 'Happy belated birthday Regulus.'

He hastily blew the candles and thanked the house elf for the forks, turning to her with Sirius's lopsided grin. 'Ready to tackle this?'

Without waiting for an answer, he started eating the dessert at a ferocious pace. It was funny how being given Sirius's appearance had made him forget about being careful with his expressions. Right now, he looked as carefree as his brother, and Emma wondered if he would have looked like that if he had been Sorted into Gryffindor. When they had finished, he sat back with a sigh.

'Best birthday I've had in a long time.'

'Really?' Emma said. 'All it took was banoffee pie?'

'All it took was to be at Hogwarts instead,' Regulus admitted. 'Let's just say that things weren't easy when Sirius left.'