It was already the end of January, and despite the discoveries and gains that Callidus had made, it did not feel like nearly enough, especially because Callidus faced numerous setbacks as well. He had successfully convinced Slughorn to write him a pass for the Restricted section, and yet, when he finally examined the books there, he learned that the one text he needed on Occlumency had been removed from the library, and Madam Pince couldn't even provide an explanation of where it went, and why it was gone. Instead, she gave an unhappy sniff, and said: "Take it up with the headmaster, if you are unhappy about the selection." Callidus had no desire to explain anything to Dumbledore. Nonetheless, Callidus was in a better position than he had been at the beginning of the month. It reminded him of the slow process of trying to decant a finicky potion, where hours upon hours of work would barely result in enough fluid to cover the bottom of a phial. But progress was still progress, and Callidus seized upon his new gains like a late-coming goldpanner seized upon the smallest flakes of gold.

Trying to fit Longbottom into his schedule was a bit of a trial, but eventually, they agreed to meet for the potion tutoring sessions on Monday evenings. Callidus hoped it wouldn't be a decision that he would regret. To say that Longbottom was clumsy and forgetful was to understate the very definition of clumsy and forgetful. When it came to potions, at least, Longbottom was the personification of calamity. It took every fibre of Callidus's will not to rain an endless torrent of vitriol upon the other boy. Frankly, he deserved to win accolades and medals for his own remarkable restraint, as well as the fact that merely being in close proximity to Longbottom was a terrible hazard to his safety and well-being.

After Longbottom had fled to the infirmary following their fateful meeting, Callidus had been relieved to learn that the brew that Longbottom had ingested had not been toxic, not because he had been particularly worried about Longbottom's life (he didn't have strong feelings about Longbottom's life except in the sense that it seemed a miracle that the other boy had even managed to survive to the advanced age of twelve), but because it meant that whatever potion that Longbottom had thrown together would be easier to work with if it didn't kill people. Callidus wasn't entirely sure, but he strongly suspected that the potion that Longbottom ingested amplified the visibility of one's magic, allowing one to see more than the typical transparent rippling that looked like heat-waves. It was why he saw those arcs of vibrant white-yellow light around Longbottom, and yet, when he tried the owl-sight potion again, the lights did not appear around Longbottom thereafter, meaning that Longbottom wasn't just some sort of magical anomaly.

Longbottom, for whatever reason, had convinced himself that he owed Callidus his life, despite Madam Pomfrey's firm assurances that Longbottom was perfectly fine, but Callidus didn't bother to correct Longbottom's misperceptions; the view was something that seemed like it might have uses in the future. Weren't Gryffindors supposed to be self-sacrificial sorts? Besides, tutoring Longbottom was such an immense challenge (or should Callidus have said an impossibility?) that he was willing to take every advantage he could, no matter how far-fetched.

Because, in truth, Callidus had thought it would be a relatively simple matter to puzzle out the potion Longbottom had used. Perhaps it would be a little more than figuring out which course book Longbottom had used, or going to Slughorn's ingredients cupboard and getting Longbottom to point out which pink petals and milky substance he had used. But no. When Callidus tried to determine which instructions Longbottom had used, the other boy had become flustered, claiming that all books looked the same to him (though the books looked nothing alike!), and when Callidus had led Longbottom to Slughorn's ingredient cupboard, he learned that Slughorn had recently restocked the shelves and according to Longbottom: 'Everything is out of place!' Life could never be easy, could it?

But dealing with Longbottom was onerous enough. Callidus didn't want to waste precious moments thinking of him as well. At the moment, he was at the breakfast table with Harry and Draco, ignoring Pansy's (admittedly droll) criticisms of Hufflepuff hairstyles, and Blaise's (Zabini had insisted that if Callidus was on a first name basis with Pansy, he might as well be on a first name basis with Blaise as well) dry interjections.

The familiar rustling sound of air resistance against parcels and envelopes marked the arrival of the owl post, but Callidus was not expecting any messages so soon. Because his attention had not been dragged away from the table to the owls, Callidus found himself watching Harry instead, not because there was nothing else to look at, but because of some subtle change in Harry's posture, that suggested a rapt sort of attention. What was going on?

Callidus followed Harry's line of sight, and saw that he was looking at Euphemia Rowle. Had Harry already gone ahead and pranked her? Harry hadn't mentioned anything, but on the other hand, Callidus hadn't exactly asked. Rowle was holding a folded parchment in her hands, wearing her normal, bored and haughty expression. But as she opened the letter, her eyes widened slightly, and a tinge of pink appeared on her cheeks. Her eyes darted to someone across the table, but Callidus could not see who. However, she returned her attention back to the letter. It was only when Rowle's friend gently nudged her that Rowle finally put away the letter.

Callidus frowned and looked at Harry. Harry's expression was strangely pleased, and yet, so too was Rowle's. He couldn't make sense of it and decided he would have to ask Harry about it later. However, Callidus's chance did not come until the weekend, when the trio were able to continue their search for Harry's mysterious secret chamber throughout the lazy late afternoon.

They were beginning on the second floor. Their careful investigation of the first floor was finally complete, which came as an immense relief; having to face the stares of so many students had been unnerving. True, most people knew better than to stare at a group of Slytherins, no matter how odd their behaviour, but the weight of the other students' suspicions was exhausting. At least it had given Draco the chance to perfect the curl of his sneer, and Callidus was mastering the art of giving menacing glares through the curtains of his inky hair. Harry mostly just lifted his shoulders to his ears, or gave the other students sheepish smiles, and failed to look threatening at all.

At this point, Callidus had almost forgotten about the incident with Rowle. But when Draco ventured off to check one of the other rooms, he couldn't shake the feeling that there was something he wanted to say to Harry.

Finally it came to him. "Harry."

His friend looked over at him, eyebrows lifted questioningly.

"I saw you looking at Rowle other day. You have a plan for a prank?"

A slow smile spread across Harry's lips. "Something like that," he answered, mysteriously.

Callidus arched an eyebrow. "Care to explain?"

"What, and ruin the surprise?"

"Is it a surprise?"

Harry's grin widened. "You'll just have to wait and see." His expression flickered and he bit down on his lower lip. "But I'm not entirely certain that it will work out like I hope." He shrugged. "Either way, she'll be put in her place."

Callidus smirked. "You're starting to sound more like a pureblood princeling every day."

Harry rolled his eyes. "Oh, leave off. I am not."

"He's not what?" asked Draco, who had returned, looking between them.

"A pureblood prince," Harry said, face scrunched up in distaste at the description.

Draco frowned. "Celebrity, certainly. But prince? Besides, Callidus's surname is Prince, so by default, he would get the label, if anyone."

"I'm sure you'd prefer that title yourself, wouldn't you?" Callidus asked, amused.

"I'm not making any claims," Draco said, with false indifference.

Callidus snorted. "No need when you can just imply it."

Draco merely shrugged in reply, a tiny smile tugging at the corner of his lips.

Harry had been a bit half-hearted about their search at first, still believing that the secret chamber with somewhere below grounds, but as they ventured through the second level corridors, he became increasingly excited, his green eyes darting back and forth, as though seeing the halls for the first time.

"I can't explain it," Harry said, when he noticed Callidus's and Draco's questioning stares, "but this feels right. It's as though I've been here before."

Draco rolled his eyes. "Harry, we passed by here almost every day on the way to our classes. Of course you've been here before."

Harry huffed. "That's not what I meant. What I mean is that I feel like I've dreamed of this before. We're close. We have to be close."

Though searching through the school for the secret chamber was a tiring endeavour, Harry's intense excitement was infectious. He seemed to almost hum with some irrepressible energy that was its own sort of magic, and reminded Callidus a little of a hound who had caught a scent, and whose brain was seized by the prey drive, completely single-minded in its aim. Even Draco, who was usually the first to want to return to the comforts of the common room, felt himself drawn in by Harry's focused energy. In this way, the trio quickly lost track of time, and before they knew it, it was nearly curfew.

"I want to keep looking," said Harry, lip jutted out in a stubborn pout. "We have Camouflage Potion. Why don't we use it? It feels like it's been ages since we sneaked out anywhere."

"It does feel rather wrong to keep obeying rules," Draco admitted. "It's like being a - a Hufflepuff, or something."

"The worst fate of all," Callidus said, wryly.

But Draco seemed to miss Callidus's ironic tone, and shuddered lightly. "It is, isn't it. All right. Let's do it. We can wait until the halls have cleared and head out after curfew. Besides, it's Sunday tomorrow so we can sleep in."

"Though we still have Quidditch practice," Harry pointed out. "But it's not that early. And I still want to keep looking either way."

Harry and Draco looked towards Callidus, as if he had the final word. Noticing the question in their eyes, Callidus shrugged. Rules didn't particularly matter to him unless they got caught. "We can keep looking."

Harry and Draco grinned, feeling a thrilled frisson from this new layer of excitement that had been added to their search.

When the trio ventured out that night, they saw that they weren't the only ones. The nights didn't belong to mischief makers alone; it also belonged to young lovers who wanted to have the world to themselves, where the cover of darkness made the words whispered in each other's ears all the more sweet and urgent. But lovers were a threat to no one but themselves, blinded by the hormones that made them take risks that they might call romantic, but that a more rational mind would know was only foolishness. And besides, the trio had an advantage that the lovers lacked: the Camouflage and Foot-silencing potions. Unfortunately, tools were only as good as the witches or wizards using them, and the potions gave the trio a sense of confidence, when they would have been better served by furtiveness and caution.

They returned to the second floor where they had left off their search. Draco grumbled about the darkness (since the torches burned low), and even Harry stubbed his toe once or twice, but none of them dared to use lumos and risk drawing attention to themselves. Though they made slow progress, there was something pleasing about having the floor all to themselves. The eerie silence make them feel like they were the only ones in the world, and the risk they were running made it seem like danger lurked around corner. Their constant utterances of: 'Open! Open!' felt less ridiculous in the dark.

But the more they searched, the more agitated and frustrated Harry became. His hopes had been too high, and Callidus had a feeling that Harry thought they should have found the chamber by this point. Instead of enjoying their little adventure, Harry became too focused on the ends rather than the means. Draco may have been oblivious to it, but Callidus noted the tightness around Harry's eyes, and his clenched jaw.

They had just finished up examining one of the classrooms, that was used in some of the upper year classes, which felt far more taboo than sneaking into unused classrooms, when Draco who was already at the door, gasped.

"Merlin, no!" he whispered in dismay, and Callidus and Harry looked up at him, worried.

"What is it?" Harry asked, his voice quiet but alarmed.

Draco had already backed away from the doorway, eyes wide and expression panicked.

"It's Mrs. Norris," he hissed, referring to Filch's sour-tempered cat. Callidus's stomach dropped.

"Bloody hell," Harry swore, expression darkening.

The three of them froze when, in the distance, they heard Filch's familiar voice singing out: "Where are you, my sweet? Have you found someone out of bed, and making mischief in the shadows?"

"He probably won't see us if we're careful," Callidus tried to reason. "We have the advantage of the Camouflage Potion."

"Merlin, I really don't want to get detention with Filch," Draco moaned. "Do you remember what he made Blaise and Millie do for their detention in first year? They had to scrub floors. With their hands! Malfoy's don't touch floors with their hands. Floors aren't meant to be touched with one's hands."

"Let's just get out of here before Filch gets any closer," Callidus said, in no mood for Draco's theatrics.

"Yeah," Harry agreed. "We can't stay here."

Mrs. Norris was already at the door, meowing urgently for Filch to come. The potion may have made the trio nearly invisible, but being camouflaged with no defense against Mrs. Norris's sharp nose. There was an evil gleam in the cat's yellow eyes, as if, like her master Filch, she relished the possible suffering of the students.

"Evil cat," Draco muttered, but he kept his voice low lest they draw Filch's attention.

The trio's movements were hurried, though they kept to the shadows where the Camouflage Potion worked best. But despite Mrs Norris's scrawniness, despite the fact that she was so skeletal that she looked like she was on her last leg, the cat was alarmingly agile. Knowing that they had a potion to silence their footfalls, the trio were already running, desperate to make their way back to the common room. They sprinted down the corridor, sharply turning a corner, but Mrs. Norris matched them step for step, like a demonic shadow on their tail.

The way should have been clear, but the magic of the castle seemed to be working against them tonight. In the dark of night, nothing looked as familiar as it should have. They ran past a statue of a winged horse that Callidus could have sworn was on the other side of the castle. He felt horribly disoriented, and his brief glances towards Harry and Draco suggested that they felt the same.

The beating of his heart was terrifyingly loud, and he felt like it would lead Filch straight to them, and all the while Mrs. Norris leapt and bound, like they were her prey, and she was readying herself for the kill. Had the second floor always been this much of a maze? And even if it was, Callidus thought that they hadn't even explored the second floor that extensively How in the world could have gotten themselves so lost? Have they made a wrong turn in the dark? Were they going in circles? Callidus thought that they should have come to a staircase by now.

They turned another corner into a darkened hallway, their legs and lungs burning, but to their horror, it led to a dead end. Callidus hadn't even realized that Hogwarts second floor had any dead ends. Luck was not at all in their favour. No, luck was particularly cruel tonight.

He heard Draco swear, in cruder language than the blond had ever used before. But the choice of words was apt: it felt like they were doomed.

Mrs. Norris had slowed her pace, and was sauntering towards them, her lantern-like eyes filled with a menacing glow. Her wiry muscles seem to ripple beneath her skin, shoulders rotating as if preparing to pounce.

Callidus was almost ready to resign himself to his fate, but next to him, he heard Harry swear, his language filled with an underlying rage that was clear, even in the dark. Moments later, Harry repeated his swear, the words more of a resolution than a surrender, and furiously, he stomped forward. The unexpected action caused Mrs Norris to falter in her step.

"Harry?" Draco called out, uncertainly. "What are you -"

But Harry wasn't listening. He moved like a warrior walking into battle, and Mrs. Norris seem to sense his intent, but she wasn't afraid of him. There was a fatality to the scene that was terrifying. It seemed so wrong, like this was too great a risk to take, but Callidus's mouth had dried and words would not come.

The next minute seemed to happen in slow motion. Mrs. Norris's tail was swishing back and forth in a cat-like signal of aggression.

"You're just a cat," Harry taunted. "What are you going to do?" He looked back towards Callidus and Draco. "Get out of here," he insisted.

Understanding Harry's purpose, Callidus and Draco edged forward, pressed against the wall to stay as far away from Mrs. Norris as possible. The cat might be able to get one of them, but she couldn't get all of them - or at least that seem to be Harry's reasoning.

But Mrs. Norris wasn't about to admit defeat. The cat took her purpose in life as seriously as Filch did. She was not about to go slinking away into the night, defeated. Callidus was a little ahead of Draco, knowing his position was more vulnerable, but he also knew that despite Draco's talk, the other boy was no true leader. Draco only led when success with assured, or when his father had his back; he was not the sort of person to stand on the front lines, where wands were drawn and sacrifices had to be made. Or to put it a little more kindly: Draco had a particularly strong self-preservation instinct.

Mrs. Norris was looking from Harry to Callidus, unwilling to let her pray elude her. Harry was standing still but Callidus was not, so she made her decision, acting on instinct alone. Claws unsheathed, she leapt towards Callidus, and he braced himself for the possibility of torn flesh and a tangle of fur, but there was an unexpected blur of motion, and a split second later Mrs Norris's body was thrown against the wall.

"Did you just kick her?" Draco gasped, behind him.

Even in the darkness, Harry's eyes were wide and horrified. He looked down at a bundle of fur and jutting bones upon the floor, unable to believe what had just done, but now was not the time for a moral crisis.

"We have to get out of here," Callidus hissed. He reached out and grabbed Harry by the sleeve, yanking him hard. As they dashed away, Harry couldn't stop looking over his shoulder at that bedraggled creature, and Callidus didn't have to see his face to know that there was guilt written all over it.

"She's fine," Callidus said, but he didn't know for sure whether his words were a lie or the truth. And honestly, he didn't really care.

The trio made their way through the twists and turns of the second floor, finally managing to find a staircase, and making their way down to the dungeon. When they enter the common room, they were all breathing hard, but Draco's expression was elated.

"I can't believe we got away!" he burst out. "Merlin, I can't believe what you did to Mrs. Norris!"

Irritated, Callidus jabbed Draco with his elbow, wondering how the blond could possibly be so oblivious to Harry's distress, because all it took was one look at Harry to know that the other boy was deeply upset. But Draco was clearly unable to understand the situation, and rubbed his side, giving Callidus an affronted look.

Harry was shaking his head, his green eyes distant as if replaying the earlier encounter in his mind.

"What have I done," Harry said, his voice barely above a whisper. He looked up at Callidus, his green eyes enormous and his expression stricken.

"She'll be fine," Callidus repeated, stepping forward and placing his hand on Harry's shoulder.

Harry was still shaking his head. "I was so furious. In that moment, I swear I could have killed her. What if I did? What if I did kill her?"

"Wait," Draco interjected, "are you upset about kicking Mrs Norris?"

"Yes!" Harry cried. "What if she's dead?"

"She's a Kneazle," Draco pointed out. "Or at least she's part Kneazle. You could bat one of those things across the Quidditch pitch like a bludger and they would be fine."

"Really?" Harry wondered, hopeful.

Draco rolled his eyes. "Yes. At least, I think so."

Harry exhaled heavily, running one of his hands through his hair and gripping the strands tightly. "I can't believe what I did. I was just - so, so angry. I just saw red and I wanted to destroy that cat for being in my way."

Draco smirked. "That was a Gryffindor level of recklessness. You have no self-preservation instinct, Harry. But it was pretty awesome."

"No!" Harry cried, flinging his hands out in frustration. "It was not. I don't even know why I was so angry. If we had gotten caught, all that would have meant was detention. Nothing about that situation justified hurting Mrs. Norris, or any animal for that matter."

"Just detention?" Draco echoed, incredulous. "Harry, it was Filch. Who knows what he would have made us do."

"Animals are hurt all the time in the wizarding world," Callidus added. "It's an inescapable fact of life and of potions. I've done far worse things to rats than what you did to Mrs. Norris."

Harry paled. "It was still wrong." He shook his head. "I don't want to talk about this anymore. Let's just go to bed."

Draco gave Harry a long look, while Callidus merely shrugged. Now that they were no longer fleeing anything, exhaustion stole its way into their muscles and bones, and their beds sounded like a haven of comfort.

It wasn't until all the boys were in bed, their curtains drawn around them, that Callidus realized that he forgotten to mention the pendant to Harry. It was something that remain tethered to the corners of Callidus's mind, that he did not often think about, and yet couldn't forget, especially on nights when he did not sleep, and could hear Harry moaning and shifting restlessly under his covers. For the most part, Harry still seemed like himself, and it was easy to ignore the existence of the pendant, but enchantments were powerful magic, and maybe this night's bizarre events would finally convince Harry to question the pendant.

But maybe it was wishful thinking, maybe Draco had been right all along, and Callidus was just jealous about Harry having an enchanted pendant. He sighed and turned over onto his side. Perhaps what was more likely was that they had just gotten caught up in the adrenaline of the moment. It was with these thoughts that Callidus drifted off to sleep.