Hermione didn't know what she'd expected to happen after she'd learnt she truly held the potential to practise pure magic. Maybe she had imagined that it would suddenly come pouring out of her like a fountain. Yet very little had changed in their latest session, much to her frustration. The most annoying part about it was how Matthew didn't seem remotely surprised. He didn't show any sign of disappointment when she tried to produce the same wisps of energy she'd witnessed in her memories. In fact, it was only through her adamance that she even got the chance to try, since Matthew was more focused on consulting further insights into her past life. She knew that he was being supportive, not wanting to pressure her or force her to reach too high a standard. But the part of Hermione's brain that demanded perfection saw it as a clear indication that he didn't expect her to be able to do it. It was completely ridiculous. He had said it would be difficult but had never once shown anything remotely like a lack of belief in her abilities. Yet the thought was still there all the same, clawing at her.

So, as she followed Matthew into the common room, she was wearing a deep frown that he hadn't yet picked up on. With practised ease, he weaved through the copious sofas, chairs, and people to reach their designated spot, putting his feet on the opposite bench and leaning back with his hands behind his head. In her view, he looked far too relaxed for what they'd just been through. Her brain was aching and that probably had something to do with her bad mood, now she thought about it. It was an irrational thing to be annoying her but how unaffected he was by it simply showed the gulf in their abilities, the size of the gap she had to bridge. Obviously, he had been doing it for longer and he had likely started off at this level, but she had never found something she couldn't do to a high standard. Besides the violin in primary school. That had been a horrendous experience.

Hermione sat by his feet, watching as he relaxed with his eyes closed. Maybe he was doing it on purpose. He was never this carefree. Maybe he was trying to show her that the only way to reach her potential was to be more easy going. If he knew her at all, he should have realised by now that that wasn't going to happen. It was likely that she was reading far too much into his behaviour, which came as part of the territory when dealing with someone so frustratingly enigmatic. He was probably trying to chill out because he was secretly tired after reaching into her mind for so long. She smiled softly at the implication he'd want to hide any weakness around her, like he was always trying to impress her. He was usually hoping to impress everyone around him, but she liked to imagine it was just for her benefit.

She leaned forward, not that he could see her. "Could I look at some of your memories?"

It was funny to watch just how quickly his eyes snapped open. "Excuse me?"

"Your memories…could I see some of them? Like you've been doing with mine? Perhaps the next time we go through the exercises."

He was sitting properly now and he didn't look too pleased about the proposition. "Why would you want to do that?"

"Well, the point of analysing my memories was to show myself that I do possess pure magic, yes? So, if I was to see some moments from your life where you were learning to use it, I'd get a firsthand view of how to operate it, how to summon it, what it should look like, that sort of thing. I think it could be really beneficial."

"I don't think it'd be that interesting really." Matthew was doing his best to act cool under the pressure but she had been around him long enough to know when he was being purposefully evasive.

"Do you? I think it'd be fascinating ."

"I'll think about it. And that's as good as you're going to get."

"I reckon that's a yes but you're just trying to torment me for a week."

He didn't respond, though he did smirk slightly, turning his gaze away. Hermione grinned as she realised that meant he was probably going to relent. It was such a different position to be in, where he was now willing to share things with her. She should have probably wiped the giddy smile from her face for fear of looking insane to any random passers-by, but it was proving rather difficult. She even attempted to distract herself with one of the numerous books that was rammed into her bag, but she was constantly getting distracted by the sensation of his eyes on her.

As time rolled by and any sign of light disappeared outside, Matthew began to tense up. She would spot him occasionally gazing around the room, looking for something. Someone. Hermione placed her book down after he did for a third time within twenty seconds, raising her eyebrow, asking for an explanation without needing to open her mouth.

"He should be back by now," he said gravely. "He's never been this late and Lupin knows that it shouldn't go on for this long, not with the protocols in place around the school."

"Where else could he be though? Harry won't be in the library. Madam Pince wouldn't allow him to be on his own at this hour, regardless of being in the school. Dumbledore's been rather clear about that." She was beginning to gnaw on her lower lip in worry. She roamed the room, her eyes landing on a head of red hair and she waved Ginny over. The youngest Weasley didn't take too long to come over, sitting in their booth with a confused look.

"What's up?"

"Have you seen Harry?" Hermione asked her.

"...no. I've been sat near the portrait hole for most of the evening. I would have seen him come in at some point. Why? You don't think something's happened, do you?"

"It's probably nothing." She was barely convincing herself. "He was with Professor Lupin tonight and hasn't come back yet. They probably lost track of time."

"Lupin? Really? He cancelled our class today, saying that he had business to attend to away from Hogwarts. I'd be surprised if he came back so quickly."

Now Hermione's heart was pounding. She looked over to Matthew, perhaps seeking some form of guidance, and found him staring once again out the window, his gaze pointed to the sky. "Full moon," he muttered before launching himself from the bench. Ginny stood up, which allowed Hermione to race after Matthew.

"Hold on!" Ginny called after them. "What are you doing? Where are you going?"

"Just stay here, Ginny," Hermione instructed her with little patience. She couldn't stop thinking about Harry being in danger. "Keep an eye out. He might wander in at any minute. We're just being…overly cautious." That was one way of putting it. They just couldn't afford the entire House being stirred up into a wild frenzy. As they barged through the portrait hole, the Fat Lady telling them that they needed to learn some manners, Hermione was struggling to keep up with her friend. "What are we actually doing? Should we tell one of the professors? Dumbledore? He'll know what to do."

"We don't have time for that," he said hurriedly. "I don't think so anyway. Imagine if the worst has happened…what could they possibly do? There's no way of knowing where he is."

"You don't think that… he's got him, do you?" She paused in the corridor, knowing that they needed to keep running but her mind wasn't able to cope with the prospect.

"I think it's the likely scenario." He spotted she'd stopped and quickly closed the distance between them, grabbing hold of her more gently than the situation should have allowed.

"Then what can we do that the professors can't?"

"We have a Tardis."

It was beginning to click into place for Hermione but there was one major stumbling block still ahead of them. "But…if we do find Harry with that…then he'll…know about you."

"Frankly, I'm more concerned about keeping him safe than keeping my secrets. If he hates me afterwards, at least he'll still be alive to do so."

xxxxxxxxxx

"I didn't think you'd follow us. I did my best to entice you without revealing my true identity."

Sirius Black's voice sounded like he hadn't used it properly in a long time. Harry guessed that there wasn't a lot of time for talking in Azkaban, or when you were on the run. He kept his wand trained firmly on the dirty man, who was surprisingly unarmed. Then he remembered what they had done to Hagrid as a student when he'd supposedly broken the rules, snapping his wand as a punishment, and it now made sense as to why the renowned criminal before him was simply holding his hands outstretched.

"You were the dog," Harry said in realisation. "You're an Animagus. That's how you've been getting around. That's how you've been avoiding the dementors." He felt so foolish. Why hadn't he considered that? It wasn't as if his own Head of House was an Animagus too.

"Foolish creatures that don't know their own weaknesses. Their egos…they never considered they could be duped and I used that against them." Black sounded pleased with himself, which just made Harry angrier. "I didn't know whether you'd be that interested in the cat. It's your friend's, isn't it? The girl. I've seen her. I've seen you all together." A shiver ran down Harry's spine. How long had he been watching them? How long had he been waiting for this? "It wasn't planned this way. You weren't supposed to stumble across us. I was improvising as soon as you laid eyes on us. This is a stroke of pure fortune, after all the meticulous planning I've gone through. It's funny how life works out sometimes."

Something within Harry was reaching boiling point. For the first time in his life, he wanted to use his magic not for some silly little spell, but to kill the man in front of him. That's what he deserved, just from the way he was still able to smile. If the grimace on his face could be called that. His parents deserved to smile so freely, not the monster that killed them.

"Do you really see it as good fortune?" Harry asked him, taking two menacing steps forward. There was no fear in his body. He was being solely driven by hatred. He could feel it consuming him. He didn't have his friends to guide him now, to hold him back. "What's to stop me from killing you right now?"

"Nothing." The simple and honest answer might have shocked Harry if he'd been thinking straight. "I'm curious to know if you'd even know what spell to use though. Still…there will only be one murder tonight. I'm rather hoping it won't be mine."

"And why's that? Why stop at one? Why not, after dealing with me, go through Hogwarts and see how many people you can take with you? You didn't care last time, did you? You didn't mind destroying all those people's lives to get at Pettigrew. You didn't consider what trauma you put their families through as a result of that. Have you gone soft in Azkaban, is that it?" He raised his wand, hand shaky. He didn't want to show Black how nervous he actually was but that was proving to be practically impossible. Maybe it would sting more to be killed by a boy who didn't know what he was doing. "You killed my mum and dad!"

"Are you going to do the same to me, Harry?"

It was almost annoying Harry how Black wasn't moving to stop him. He felt a primal urge to hurt him as much as possible, which made his grip around his wand deathly tight. "It wouldn't be the same. Because they didn't deserve what you did to them. You do. You killed them." He was fighting back sobs. There were too many emotions swirling within him to deal with.

"I don't deny that. But if you knew the whole story…"

"The whole story?" Harry was incredulous, incandescent with rage and fury. "You sold them to Voldemort. That's all I need to know."

"Just listen to me. Before you do what you have to do. You'll regret it if you don't. You don't understand." There was something new in Black's voice and the way his hands shook. An urgency. His gaze kept shifting over to the cat lying on the bed, still messing with something out of Harry's view.

"I understand more than you give me credit for," Harry told him resolutely. "You never heard her. You never had to listen to it. My mum…doing everything she could to save me…as Voldemort climbed those stairs…you never had to listen to her screams. That was you. You did that."

Harry didn't know what he was going to do but he was stopped from doing anything by the movement of a ball of ginger fur. Crookshanks jumped down from the bed, ran straight past Harry, and came to a stop in front of Black. The cat sat down, its inquisitive yellow eyes staring up at Harry. He gazed back at it. He'd come to save it but now was it obvious that Crookshanks had been in league with the murderer? Had he purposefully been led astray, his loyalties being played against him. If it was prepared to stand by Black, to die alongside him, then who was Harry to not give it its wish? If Black tried to save it, that only proved he cared more for an animal that he had done for his parents. Like he'd told himself, Hermione could get another one, one that hadn't been against them from the start.

Harry shook his head, his attention returning to Black. This was his moment. He'd been thinking about this since that day in Hogsmeade when he'd discovered the horrible truth. He shouldn't have been even hesitating, giving Black the chance to do something. But the man just stood there, looking at him with something akin to sadness. But Harry knew that was impossible. Someone so evil couldn't feel such an emotion.

Blood was pounding around his head so loud that he didn't hear the footsteps until it was too late. He saw the door slam open, too shocked to act. He felt his wand leave his hand as a well timed Expelliarmus was fired at him. Professor Lupin caught it deftly as he strode into the room, his face pale as he looked at the scene before him. Harry's heart dropped. He had wasted his chance, his nerve getting the better of him. He had had the opportunity to rid the world of Sirius Black but now he was going to be handed over to the dementors. It was an awful fate but not the one that Harry had wanted to enact.

"Where is he, Sirius?" Lupin asked. His voice was hollow.

Harry was confused. What was he talking about? Who was he talking about? He watched as Black slowly raised his hand, pointing in Harry's direction. What was happening? Lupin would obviously know he was here. He could see him. But the professor's gaze seemed to go just past him, staring at the bed. Harry wanted to look but also didn't want to give Black the chance to escape.

"But then…" Lupin was scratching at his chin, which was uncharacteristically unshaven. He was looking at Black with an unwavering focus, like he was trying to read his mind. He moved over to the bed, wand still out, and quickly looked down at the bed. Something in his eyes flashed before he returned to his original spot. "Why hasn't he shown himself before? Unless…" His mouth hung open. His eyes went wide. "Unless you switched…unless he was actually the one…and you didn't tell me."

Harry was growing nervous. "Professor, what's going on?"

He'd barely finished the question when everything seemed to go wrong. He could feel his mouth go dry as he watched Lupin lower his wand before walking to Black's side. It was like the bottom dropped from his stomach as he witnessed the professor hug the other man as if they were brothers.

xxxxxxxxxx

Matthew barely paused as he barged through the Tardis doors, nor did he slow down as he took the steps two at a time to reach the console quickly. Hermione had the forethought to close the doors as she staggered in. He was already working away at the controls by the time she reached him, and she watched in fascination as his hands waved over the instruments like a conductor controlling their orchestra. The ship came to life at its touch, thrumming eagerly as the engines warmed up. Hermione was struggling to follow his every move, the boy bouncing around energetically.

"Aren't you forgetting something?" she asked, not wanting to disturb his rhythm but unable to ignore the doubts in her mind. "We don't have any clue where Harry is. It's all well and good having a Tardis, but you don't know where to land it."

"Ye of little faith," he shot back at her, still whizzing around. He cranked some sort of wheel that squeaked noisily and he grimaced. "It's been a while since I did this. And a while since she was put through such a strain." He patted the console affectionately. "But she'll be up to the job, I know it. She has to be."

"Are you going to explain what you're doing then? You normally like to impress me."

Matthew grinned. "We're assuming that, if Harry is missing, then Sirius Black must be involved. Think about it, Hermione. I landed a hex on him that night he broke into the common room. And, because I'm super clever and have a brilliant machine at my fingertips, I should be able to use that. If I can lock onto the magical signature, the Tardis can follow its imprint. Because, let's face it, know one's been using magic like mine. It's basically clinging onto Black like a stain and he doesn't even know it. A homing beacon that will pull us to Harry."

"You mean you could have used this earlier to find Black? As soon as you fired the spell at him…"

"Technically. But who am I to judge a man? That's not up to me. And it's been playing on my mind, about that night. How come he missed?"

Hermione rubbed at her head. She could definitely feel the start of a migraine approaching. "What are you talking about now?"

"It was just me and him when it happened, and I was distracted when he fired at me. If he's such a notorious and powerful killer, how come he couldn't take me out? Why did he only clip my shoulder? What if he chose to miss?"

"Why would he do that?"

"I don't know. Maybe I'm reading too much into it. Maybe he's out of practice. But it put some doubt into my head. Though that doubt is suddenly leaving me now Harry could be in trouble. It's interesting how your perspective can change when your friends are in danger."

"What if Harry isn't with Black? What if he just decided to have a stupid wander around the castle? You know he doesn't like to listen to the rules. He could be with Hagrid, for goodness sake!" She ran a hand through her hair. "You could be taking us straight to a criminal for no reason."

"We'll deal with that when we get to it. We can't take the chance."

"No, we can't. You're right." Hermione joined him by the console. "You mentioned the full moon earlier when Ginny told us Professor Lupin was missing today."

Matthew hesitated, risking a quick glance at her. "I did."

"How long have you known?"

This time he fully turned his body to her, a frown on his face. "You knew too?"

"That he's a werewolf? Ages! Probably since Professor Snape forced us to learn about them for no apparent reason, straight after Lupin went off sick. It was too big a coincidence to ignore."

"Then there was his boggart, which turned into a moon. It was pretty simple to connect the dots."

"Don't forget the lunar charts we use in astronomy. He always seemed to be ill around the full moon."

"You never said anything."

"Neither did you."

"It's an illness. If he wanted to keep it to himself, that was his decision. It wasn't as if he was hurting anyone, as long as he was managing as he seemed to be. The illness shouldn't define the man. He's more than what just runs through his blood."

"Precisely," Hermione whispered, staring at him.

Matthew tapped the edge of the console before snapping himself back to the matter at hand. He rushed to the other side. "I think the old girl's ready."

"Ready for what?" She moved her head to look past the central column, and didn't particularly like the look of the grin on his face.

"Ready for me." One of his hands began to glow and he placed it on a small, flat surface. The Tardis shuddered for a second, the lights dimmed, and then one of the main levers pulled itself down, the column beginning to move.

xxxxxxxxxx

"No!" Harry shouted. "I can't believe it! I won't believe it!"

Lupin disentangled himself from Black and looked towards the shaken boy. "Harry…you need to calm down…"

"You and him…all along!"

"Harry, please calm down. I can explain."

"I trusted you!" Fresh tears were filling in Harry's eyes, obscuring his view but he didn't dare wipe at them. He didn't want to give them the satisfaction. "All the sessions we spent together, you teaching me a spell that would help me when I met the very man you were in cahoots with. You're friends with him!"

"You're wrong, Harry." Lupin held up his hands, lazily clinging onto his and Harry's wands. Harry considered making a grab for it, wondering if he could overpower the older man. "I haven't been Sirius' friend, not for a long time…but I am now. Let me explain."

"You're the one who's been letting him into the castle. Why?"

"I've never once been involved in getting Sirus into Hogwarts this year. What can I do that'll make you listen?" He threw the wand over to Harry, who catched it numbly. He'd just been about to lunge at it so at least he hadn't needed to embarrass himself. "There…you're armed now. You can do what you want to us. But you had that same chance with Sirius before I got here and you hesitated, which makes me believe that you want to listen."

Harry fiddled with his wand, not knowing what else to do. "If you're actually telling the truth and you haven't been in league with him, then how are you here? How did you know where he was?"

Lupin nodded his head and produced an old piece of parchment from his worn jacket. Harry had seen him with it before during their sessions but had never thought to ask about it. "If I may…" He slowly held out his wand, making a big deal of only gesturing it towards the paper. "I solemnly swear that I'm up to no good."

Harry watched on in amazement as the parchment began to swirl with ink, lines being drawn, intercrossing with one another. He made sure to keep one eye on Black, though he still hadn't moved since Lupin had released him. He didn't want to get too close, still not fully trusting the professor, so allowed him to explain the object instead.

"As you can see, it's a map…of the school. I discovered the Weasley twins had it fairly on in the year. They claimed to have stolen it from Filch's office. I couldn't believe that it had lasted all those years." He held it out, showing it off, pointing to a particular spot. "You'll notice everyone's names…ours are all together."

"We're in the Shrieking Shack?" Harry asked as he glanced at the neatly scribed label, before looking around the room. It definitely fit the bill and explained why he had been walking through that tunnel for so long.

"Indeed we are. I should have known where you were heading. I've spent enough time in here. But, thanks to the map, I was able to spot something that rocked my perception of the world. You see, I had to cancel our session tonight because it's a difficult time of the month for me. Which gave me the opportunity to check the map to ensure that you were returning to Gryffindor Tower safely. Even whilst I was not there, I still wanted to look over you."

"Do you want me to be grateful?" Harry spat.

"No…just for you to understand. I watched as you began to walk away, only to enter the outer grounds. I couldn't tell at first what you were doing but then I saw Sirius' name. And another that I didn't think possible. You chased both of them here and I panicked. I risked everything to come here."

"Both of them? Did Crookshanks show up on the map too?" He reckoned it must be severely overcrowded if pets were on there as well.

"He didn't…but you were chasing two names nonetheless…and both are still in this room."

xxxxxxxxxx

Sparks flew from the console as the room spun wildly. Hermione was clinging onto the metal railing as her legs flailed, whilst Matthew was somehow keeping his feet, trying to maintain a semblance of control. The Tardis groaned and rocked.

"Is it always this violent?" Hermione shouted.

"Only sometimes!" Matthew responded, unable to hide his smile. "You know, she really isn't designed for these short hops! It's like taking an Aston Martin to the supermarket! It's beneath her!"

"Could she deal with her ego once we've found Harry?"

He rubbed at the console. "Don't you listen to the mean girl? If you've got an ego, then it's only warranted!" Matthew had enough time to narrow his eyes at her. "She's having to follow the path of the magic, connecting me to the spell. That means she can't afford to properly dematerialise because she might lose the signal, for lack of a better term."

"What does that mean?" She had to raise her voice again as more sparks erupted, showering them in hot shards of light.

"It means this isn't going to be a typical landing."

"And that's bad?"

"Well, it depends on your perspective. For me, I'm rather excited! It's been ages since I had a crash landing!"

Hermione didn't know what to do as he began to laugh, the room only spinning faster.

xxxxxxxxxx

"We should kill him now!" Black barked, much like the dog he'd pretended to be.

Harry backed away fearfully but Lupin held out a hand. "Harry deserves to know everything before that happens." He walked past Harry, heading towards the bed. He picked something up and Harry was surprised to see the head of a rat poking out from his grip. A rat he'd definitely witnessed running through the common room plenty of times.

"Is that Scabbers?" What was happening? Maybe he was going insane? Or he could be dreaming. It definitely had to be a dream.

"That's what they've been calling him…but the map knows his true name. I couldn't believe it when I read it. My eyes had to be deceiving me."

Harry noticed that a small trickle of blood was dribbling down Lupin's hand as he brandished the rat. Crookshanks snarled and stood on his hind legs at the sight. So that was what he had been toying with. It was evident that Ron had been right about the cat having it in for his pet, even though that didn't explain anything about why both men were so transfixed by it.

"But it's just a rat!"

"That's no rat!" Black's voice was croaky as he spoke and his hands twitched as he yearned to claim the creature for himself. "That's an animagus, like me."

"A wizard, Harry." Lupin held it by the tail, taunting it. "By the name of Peter…what's that noise?" The professor frowned. Harry could hear it too. Black cupped his ear intently. It was a strange groaning noise, almost like engines. And it was getting louder. Harry barely had time to register that fact before one side of the wall caved in, the wood shattering and splintering. They were sent to the floor as a large blue box skidded through the room, only coming to a stop when it collided with the opposite side of the Shrieking Shack. Harry stared up at it, dumbstruck. What on Earth was a police telephone box? He was only made more confused when the seemingly wooden doors creaked open, smoke billowing out from within.

Matthew's head appeared through the grey cloud. "You probably have a lot of questions."