Bagsy had spent her free period in the familiar nook of the library, drawing up a plan for a grow-into-shape key, and noting to herself that she needed to get better at naming her inventions. Then again, so long as it got her into the greenhouses, she supposed it didn't matter what it was called.

When Mezrielda, having had Defence Against the Dark Arts last thing on a Thursday, finished her classes and came to join her, she looked at the blueprint sceptically. 'What is this about?' she asked, sitting down demurely and neatly organising her homework in front of herself. Bagsy knew Mezrielda would spend the evening looking at the work in annoyance and rushing through the questions, as she always did. Bagsy had previously wondered how Mezrielda could find studying so boring and put so little effort into it and yet do so well in class. Having seen the paces her parents put her through during summer, Bagsy now understood.

'The greenhouses,' Bagsy explained, looking up at her. 'I tried to sneak into them last night during Astronomy. They were locked.'

'Ah. I see.' Mezrielda winced. 'I'm guessing the unlocking charm didn't work?'

Bagsy looked down at her sketch sulkily. 'No.' Of course, what Mezrielda had meant was that Bagsy hadn't been able to cast the unlocking charm.

'What does that have to do with this?' Mezrielda asked, tapping what Bagsy was working on. Currently, it was a collection of doodles of different potions ingredients that, if combined correctly, should make some form of slime. This slime would be poured into a needle that could inject the substance into a keyhole, stopping it from expanding and solidifying until it was already in the key hole and could expand into the correct key shape. The needle contraption was sketched in detail next to the ingredients.

'It's going to be a grow-into-shape key maker,' Bagsy explained.

Mezrielda arched an eyebrow. 'Where you pluck these names from I have not the foggiest idea,' she murmured. 'Don't you have enough on your plate already? What with the broom upgrades for Hufflepuff and whatever favour it is Tod has you running about doing?'

Bagsy shrugged. 'I suppose. But you're not really one to talk – doing your Animagus favour is taking up a third of my time.'

Mezrielda had the good grace to look sheepish at that. 'True.' She sighed. 'Bagsy, give me the spider slippers and gloves. I'll sneak to the greenhouses, unlock the door with my magic, and retrieve the mandrake leaves.'

'No,' Bagsy found herself snapping harshly. 'Sorry. It's just that if you get it wrong, mandrake screams can be fatal.'

'Fatal?' her friend asked, looking shocked. 'But they're plants.'

'Plants can be dangerous,' Bagsy retorted in amusement. 'I guess you don't know everything, after all.'

Mezrielda glared but then broke into a smirk. 'I suppose you're correct. Besides one tiny fact about one rare plant, I do know everything.'

'A fact that if you don't know it could get you killed,' Bagsy pointed out, enjoying the scowl that took hold of Mezrielda's face as she glowered at her.

'I have plenty of knowledge of Herbology and its dangers. If I stretch my mind, I do recall Professor Wattleseed saying something about man-eating fly-traps in our first year.'

Bagsy gave a small mock bow. 'My, my, I'm impressed,' she teased, delighting in the reveal that yes, Mezrielda's scowl could grow fiercer. 'My point is, while you're better at everything else, when it comes to dangerous plants, I know what mandrakes look like, and why they're dangerous, and you don't. If you go in there alone you'll be in danger – and I don't have two sets of spider gloves and slippers.'

'Alright, then,' Mezrielda relented. 'Make your lock-picking gismo. Just try to get an appropriate amount of sleep.'

'Sure.' Bagsy beamed, going back to her work.

At two in the morning Bagsy had long since forgotten her promise to Mezrielda. She had borrowed a horde of different old boxes and diaries that had locks on them from lost property. According to Nurse Jones, they'd 'been there forever, forever they've been there…' so Bagsy didn't feel too bad about taking them. There had also been a handful of padlocks left behind.

Bagsy had easily combined malleable metals, a vial, and some thick plastic into a few make-shift needles. She had also easily concocted, after thirty-four different variations, a potion that expanded to fill the hole it was in and then solidified on contact with air.

Placing this potion into one needle, and the activator ingredient that would make it expand and solidify into another, Bagsy would carefully slot both ends of the needles into a lock and inject the potions inside of the hole. After a few moments pause, the potions would expand to fit the shape and solidify. Unfortunately for Bagsy, the first few times she forgot to insert a handle and was left with a blocked lock. The next few times, she wasn't quick enough, and when she finally did manage to get a metal handle into the liquid as it expanded, once it solidified it refused to turn. Bagsy realised that, far from forming the perfect key shape, the liquid merely filled the entire hole and refused to budge.

The next few days and nights Bagsy spent locked up in her room, trying to find a way to make the potion expand intelligently – so as to make the perfect key shape and not fill every available crevice – but she could think of nothing that would achieve this. When she grew too frustrated with the key work, she'd turn back to improving the Hufflepuff brooms, or figuring out how to improve the calibration on the mag-net bat and ball.

By the time Sunday dinner arrived Bagsy had slept not a single hour, nor taken a single step outside of her room. She trudged to the Hufflepuff table and sat down with a flop. The food appeared, and the students began to eat and Bagsy sat there, staring at the table, having forgotten what cutlery was.

'This is ludicrous,' Bagsy heard someone say and turned her head slowly to see who it was. Mezrielda was shaking her head and pursing her lips at her. 'How much have you slept since we last talked?' she asked firmly. Bagsy blinked at her slowly, then reached for her glass of water, taking a sip. She realised too late it was one of the gravy boats and made a disgusted face. 'That's it. Give me the spider slippers and gloves, now,' Mezrielda demanded. Bagsy handed them over and Mezrielda put them into her bag. 'Go and sleep, Bagsy. I'll get the mandrake leaves. Don't let anyone ask you to do anything – no broom modifications, no nothing. Just sleep.'

Bagsy nodded and rose from the table, a feeling of warm excitement livening her bones at the idea of curling up in her bed and closing her eyes.

Mezrielda heaved a sigh, standing up as well. 'Come on. I'll take you. You'd probably get lost given the state you're in.'

Bagsy nodded and let herself be led from the great hall. However, they'd only made it halfway before it was evident just how exhausted Bagsy was. The third time she tripped over her own feet Mezrielda sighed deeply and led her to a broom closet. 'Take a nap in here for ten minutes,' Mezrielda murmured, gently lowering Bagsy, whose eyes were already shut, onto the floor amongst the cleaning supplies. 'I'll wait outside.'

Bagsy nodded, having heard not a word, and let herself drift into a pleasant sleep, leaning against a mop. She was beginning to dream about turning into a spider, or a small, fluffy rodent, or some combination of both, when she was rudely awoken by someone hurriedly shuffling down next to her.

Startling awake, Bagsy peered through the darkness. 'Hello?'

'Ssh!' Mezrielda whispered back urgently. Bagsy did as she was told. It didn't take long for her to notice the heavy, burdened footsteps of Professor Blythurst walking by the broom closet, but it was the click clack of someone with very high heels that caught her attention.

'I can't….. huff … take this… huff … to see him,' Blythurst gasped out, his voice barely audibly through the door Bagsy and Mezrielda were listening through. 'The journey would finish me off. What's… huff… left of me, anyway.'

'I hadn't realised your condition had deteriorated so,' Professor Starrett responded, a hint of sympathy in her cold voice. Blythurst grunted a confirmation. 'I'll lock this away with the rest of my confiscated items, then. If your illness improves notify me. Warpdoors can be used anytime.'

'Is that a new invention?' Blythurst's voice was fading as he and Starrett reached the end of the corridor.

'Yes. Invented by the very man you most need to visit.'

'If you think I need to visit him,' Blythurst responded ruefully, 'you do not understand the situation.' With that, their conversation ended. Mezrielda and Bagsy sat in silence for a while.

'Lumos,' Mezrielda incanted. The small space lit up. There wasn't much room between them, and Bagsy was too tired to move, so she let Mezrielda figure out the puzzle of escaping the broom closet. It didn't take her too long.

'What was that about?' Bagsy yawned as Mezrielda helped her to her feet and pulled her out of the closet.

'I haven't the slightest remnant of an idea,' Mezrielda murmured, narrowing her eyes and looking down the corridor in the direction Blythurst and Starrett had gone. 'But when I heard them coming our way I could tell from their tones they were talking about something private. I…' Mezrielda trailed off. 'I suppose I was being nosy.'

'That's a first,' Bagsy laughed weakly. 'Usually I'm the nosy one.'

'Maybe it has begun to rub off on me, then,' her friend joked in response. 'Come on. You look like a panda the bags below your eyes are so big. You need more sleep.'

Before Bagsy new it, Mezrielda was waving goodbye to her as she crawled through the barrel into the Hufflepuff common room. One blink later and she was curled up in her bed in her private room, eyes drawing heavily closed. It felt like the most luxurious privilege to rest her body, eyes and mind, and Bagsy repressed a joyous shiver as she slipped into dreams.

Monday rudely awoke her, sunlight streaming in through the windows. Bagsy, still feeling years behind on sleep, barely managed to crawl her way through the morning's double Charms lesson. She shamelessly curled up on the window seat in the library nook during personal study, her living stampelia shading her from the sun, and then stumbled, yawning, to the last lesson of the day; Potions.

Blythurst was late, as usual, and did nothing more than scribble barely legible letters on the whiteboard. Thankfully, she could just about make out the words 'wideye' and that was all Bagsy needed to get going. She flipped to the corresponding page of Beyond the Fundamentals: What Makes Potions and set to work. Unsurprisingly, wideye potion helped wake people up.

Mezrielda was shooting her odd glances all lesson. 'Don't get any ideas,' she whispered at the end of the lesson. 'Nothing can replace the real thing.'

'What are you talking about?' Bagsy asked, furrowing her brow tiredly in confusion.

'Nothing,' Mezrielda breezed, as if she'd never spoken. 'I'm famished. Let us get to dinner quickly, please,' she added, setting a fast pace for the great hall. Bagsy shouldered her heavy bag and followed obediently.

Once they'd sat down, and with a glance around them, Mezrielda slipped Bagsy her spider slippers and gloves below the table.

Bagsy fumbled, hiding them in one of the many pockets she'd added to her robe. 'Did you get the leaves?' she asked.

Mezrielda nodded, flashing some green foliage hidden up her sleeve. 'I snuck them out of the greenhouses last night,' Mezrielda explained, 'but that's not all…' Glancing at the teacher's table, Mezrielda leaned closer to her. 'As I was leaving, Starrett nearly caught me.'

'Oh no!' Bagsy gasped, horrified, waking up slightly at the news.

'My thoughts exactly. Well, not exactly, I'll admit I said something a little more colourful. Still, I said it quietly, and crawled onto the ceiling. She didn't notice me.'

'That's a relief.'

'To be sure. But as I said, that's not all…'

Bagsy considered Mezrielda silently, not sure what was coming next.

'I followed Starrett as she completed her rounds of the school. She caught a student out of bed, gave instructions to an elf, and spent an age staring out a window at Hogwarts lake like it held the secrets to her challenge with verticality.' When Bagsy tilted her head in confusion, Mezrielda waved her hand dismissively. 'I'm mocking her shortness,' she explained.

'Ah.'

'Eventually, once she was done dilly dallying, she ventured into a locked room I've never seen anyone else enter. It's on the second floor, near the main staircase. I reckon that's where the confiscated items we heard her talking about yesterday are stored.' Mezrielda's face turned a shade of cunning that sent a thrill of delight through Bagsy. 'I reckon that's where she's hidden your wand-training wheel.'

'I know what we're breaking into next, then,' Bagsy added. Mezrielda gave an approving nod, spearing a potato with her fork and taking a confident bite of it.

Bellies filled, Bagsy and Mezrielda left the great hall early.

'Starrett usually converses with Fitzsimmons for a bit before she leaves the hall, that should give us enough time,' Mezrielda murmured. With each step they glanced around themselves, peering down hallways, eyeing paintings, and looking through doors. They didn't want to be seen. 'Here.' Mezrielda came to a stop at the top of a staircase. 'Hold on for a moment…' she cautioned.

With a yelp, Bagsy clutched the railings as the staircase shuddered into movement. 'I don't think I'll ever get used to that…' she said. Mezrielda held back a snorted in amusement. 'Oh, shut up,' Bagsy muttered, without malice.

'Follow me,' Mezrielda said once the staircase came to a halt. Bagsy followed her as she was led onto a corridor and finally to a door. 'This better be worth it… it wasn't easy following her here,' Mezrielda mumbled, pointing her white wand at the lock. 'Alohomora.' With a clunk the door swung open. Mezrielda shot an arrogant look back at Bagsy.

'Yes, yes,' Bagsy droned. 'Oh, how amazing you are.'

'Precisely.' Mezrielda waltzed into the room, her sleek hair swishing behind her. With a fond roll of her eyes, Bagsy followed.

For such a small room, it sure fit a lot into it. Bagsy saw all manner of sweets, chocolates and ice-creams snatched from student's hands and stuffed into longevity boxes. Bagsy wondered how long these brand of longevity boxes could preserve the food within, and if any of it was still good to eat. Her mouth was already watering.

Higher shelves held odd looking artefacts, books, constructions and clothes. Some of the clothes had thick, heavy chains wrapped tightly around them, sealed with a padlock, and the spiky rolling pin whose spines swayed from side to side sent a shiver down Bagsy's spine.

'Aha!' Mezrielda intoned triumphantly, presenting Bagsy with her wand-training wheel. The silver band with odd coloured beads stared up at Bagsy from Mezrielda's palm, glinting in the torch light.

Gingerly retrieving her hornbeam wand from her robe, Bagsy carefully pulled the wand-training wheel onto it. 'It exploded last time I tried to use it,' Bagsy admitted, flicking her wand from one side to another, trying to see if she felt more magical than before. She didn't.

'Yes, but it also lit up,' Mezrielda reminded Bagsy, who shrugged.

'It means I can now work on improving it,' she said, inspecting the wand training wheel to see if it'd been damaged. As far as she could tell, it hadn't been.

Mezrielda walked around the room. 'There are some highly intriguing items in this place.'

Bagsy looked up from her wand, eyes tracing over the curious items on a shelf near her. Something caught her attention, as if her eyes were drawn to it by magic. It was a small, clear rectangle. Warped out of shape by the glass, but still recognisable, Bagsy saw a wasp within the substance. The item seemed entirely ordinary and unexceptional next to the oddities in the space, but Bagsy's eyes were telling her something different. She couldn't explain it. It was as though there was a blanket on top of the item, hiding it from view, but Bagsy's eyes simply saw through it.

Without any thought, Bagsy reached out towards the thing.

'Careful!' Mezrielda cried, reaching out to bat Bagsy's hand away. 'We have no clue what-'

Just as Mezrielda's palm began pushing her arm to the side, Bagsy's fingers caught the edge of the glass rectangle. It was as if an electric current raced through the two of them, holding them like statues in place. The world around them swirled and whizzed into a tornado of blurs. Bagsy couldn't scream, it was as if all the air was sucked out of her body.

Then, as suddenly as it had happened, the world snapped back to normal, and Bagsy was standing, glass rectangle in hand, Mezrielda clutching onto her arm, in the centre of a large and grand entrance hall. The tiled floor gleamed like a mirror, and a double staircase arched above them to form a mezzanine. Deep brown oak doors with gold knobs led off in all directions whilst ornaments, flowers and plush sofas filled the space with luxurious colour.

'I told you to be careful,' Mezrielda hissed, head turning to take their new surroundings in. When Bagsy realised there was fear and confusion in Mezrielda's voice, it occurred to her how much trouble they could be in. Mezrielda wasn't even letting go of her arm, and a good thing too, as the next second the doors, stairs and walls around them began to stretch and curve. A feeling of dread and dizziness harshly hit Bagsy's stomach and head, and she let out a groan of pain she found echoed in Mezrielda.

Bagsy squeezed her eyes shut, and when she opened them she was stood on a thin, and long, set of stairs over a dark abyss. They led upwards to a door, only the door was open and led to more steps that took sharp right angles and looped back around, always going up, but somehow always coming to meet with the steps below them. Bagsy's mind swam with the paradox before her.

The darkness below them wasn't darkness at all when Bagsy took a moment to look. It was a patchwork of black and white shapes that made her eyes fuzz and struggle to focus. 'I'm going to be sick…' Bagsy warned, squeezing her eyes shut again.

'I'm afraid…' Mezrielda gagged, 'I may be in a similar… position…'

Now Bagsy felt truly afraid. If Mezrielda didn't know what to do they must be doomed.

'Terribly sorry, let me turn that off for you. Contortion cessation!' a posh voice cut through the illusion, and the paradox steps, black and white shapes and open, pointless doors disappeared with a pop. Bagsy and Mezrielda fell to the ground, gasping as if they hadn't breathed in hours, and clutching their stomachs. 'But, really, one can't expect to be free from intruder precautions when one is an intruder.'

The world was spinning around Bagsy and she could barely keep both her eyes open at the same time, but she managed to raise her head to look at who was talking. A tall man with a black, curled moustache and a long, two pronged and translucent cloak over a suit regarded them. He was leaning upon a black and yellow cane with a wasp carved onto the handle. Bagsy could tell that below his expensive attire he had incredibly long, and thin, limbs. The man offered down a hand and Bagsy hesitated, thinking briefly of Cora Foncée. She had seemed friendly at first.

Pushing the thought from her mind Bagsy took the man's hand and allowed herself to be helped to her feet. Mezrielda followed suit.

'Ah, I see you used one of my warpdoors to get here. Let me guess…' The man eyed their robes. 'Hogwarts students, I presume? That must mean this was the warpdoor I sent for Theophos.' He paused. 'You'll know him as Professor Blythurst, of course. I'm not surprised he elected not to use this. It was a long shot, to be sure, but I had to make the offer.' With a dramatic sweep of his cape, the man buzzed away from them, muttering to himself about the railings needing dusting, or the chandelier replacing, as he went. He stopped at a set of double doors leading to a large living room. 'Well, come on, then.' He indicated they follow him.

'I'm sorry, it's only…' Bagsy trailed off.

'Who are you?' Mezrielda finished for her.

The man smiled. 'Where are my manners! I'm Opius Pepsini. Charmed. Now, please, do make yourselves at home.' He gestured to the living room again.

With an unsure glance at each other, they followed him.