The dust began to settle as Matthew managed to clamber out of the blue box. He paused to give Hermione a hand of assistance, only serving to confuse Harry more as she appeared on unsteady legs. Her hair was wild but that was perfectly understandable with the chaos she'd just been put through. She was definitely going to recommend introducing seatbelts for future flights, not that the Tardis had many seats to begin with. They looked at the scene before them, stepping over the broken planks of wood almost apologetically. Wind was coming through the rather large hole they'd accidentally created and a village, quiet and so at odds with the disarray around them, sat in the distance.

"That's Hogsmeade," Hermione commented, still slightly sputtering from the amount of dust they'd kicked up. They'd been there so many times that it was instantly recognisable. It was so close that they could practically smell Honeydukes, if it hadn't been for the stagnant odour that seemed to be imprinted into the walls. "Are we in the Shrieking Shack?"

Matthew was instead looking for something else, his wand pointing whichever direction his eyes went. "Where is he, Harry?"

Frankly, Harry had other pressing questions. "What is that thing?" he all but shouted. Maybe his ears were ringing from the impact. Maybe he was just too stunned to speak normally. He could barely tear his gaze away from the thrumming box. It seemed to glow with life but surely that wasn't possible. The doors were closed now but he'd definitely seen a dark cavern within, again something that couldn't be real. He must have got a bang to the head because he had to be hallucinating.

"Where is he?" Matthew wasn't going to answer those queries just yet, not when there were other, more dangerous, matters to attend to. And perhaps he was trying to delay the inevitable fallout that came with the truth being unveiled. "Sirius Black…where is he? We know he's here."

Hermione was bent down, tending to Harry, running a hand over the scratches that had formed on his forehead. She was hoping that they'd just been caused by their unorthodox arrival rather than anything that had come before. "He means to first say that we're very glad to see you're okay. You gave us an almighty worry. I was an emotional mess when we realised you might be missing." She gave him her best attempt at a smile but the fear she'd been feeling threatened to overwhelm. She was forced to give him a hug just to hide her increasingly tearful face.

But Harry was too dumbstruck to focus on that, moving his head to look at Matthew instead, who was still slowly walking around. "How did you know Black had me?"

Matthew nodded his head towards the Tardis distractedly, not that Harry knew it was called that. "That explanation can come later."

Harry was on the verge of exploding, witnessing more secrets being hidden from him. He'd had enough of it. This was all but confirming that something had been going on between the two of them whilst he'd been distracted with his patronus work. He just hadn't been expecting anything like this. How could he? Even his imagination wasn't this wild. He was going to start shouting at his friend to actually pay him attention when he noticed some of the splintered wood moving. The first face to appear was furry and ginger, large yellow eyes blinking through the debris. Hermione was shocked to say the least and instantly left Harry's side to help her pet to emerge properly.

"Crookshanks?" she gasped, picking the kneazle up. "What are you doing here? How did you get here?"

Harry glared at the creature, still remembering where its loyalties seemed to lie. "He's the reason I'm here. They lured me here."

"How…" Hermione was at a loss for words, even more so when the wood appeared to bulge upwards, Lupin shaking it from him. "Professor?" She blinked a few times, processing the unexpected information. "I've got so many questions right now."

Matthew gave him a hand to help him up, but that only put Harry more on edge. "Be careful. I still don't know whether he's working with Black."

It was a good job that Lupin was already on his feet and dusting himself off because Matthew let go of his hand instantly. Both he and Hermione took a few steps back, joining Harry by his side. The professor shook his head at their visible caution before beginning to clear up more of the mess, looking to find his friend in the rubble.

"I've already told you that I was never working with him, Harry. I thought we'd gotten past that point by now." His voice was more tired than ever. Having the stuffing knocked out of you had that sort of effect.

"Has he also told you that he's a werewolf?" Hermione asked.

Harry's mind was going to explode if one more surprising revelation was made. He couldn't take it. "What? He's not a werewolf! Don't be daft!" But he saw how Lupin's expression shifted, still clear despite being bent down. And, now he thought about it, daft didn't begin to cover him challenging the deranged friend of his dead parents whilst an ominous blue box stood partially entrenched in the wall. It was borderline mental.

"I was going to tell you when we came to it in the explanation," the professor tried to tell him.

"What else have you been hiding from me? How haven't I seen this before? That potion Professor Snape gave to you when we were together…"

"...was, indeed, wolfsbane potion. Something that relieves the worst side effects of my affliction, rather than actually curing it. It's the best society has to offer for my kind."

"Why do you think he's working with Black?" Matthew asked. His wand hadn't moved.

"They…they hugged," Harry said, reliving it all. "They know each other. They're friends."

"And you never said anything all year?" Hermione shot at him. "Does Dumbledore know? Surely he wouldn't have hired you if he'd known."

"Dumbledore knew that we were friends growing up. Neither of us knew how Sirius was getting into the school. I was prepared to defend Harry tonight, and I still am, just not from Sirius. Not now I understand what happened all those years ago." He let out a soft exclamation as he moved another board, a pale face uncovered. Black, as frail and weak as he was from the years he'd spent in Azkaban, hadn't reacted too well to a giant box crashing through the building. His eyes were closed but they could see his chest was still gently rising and falling. Matthew and Hermione immediately had their wands trained on the figure, which was no mean feat for the latter as she still clung onto Crookshanks. As Lupin leant over the body, the exposure to the cold air must have woken Black up, for he started to blink uncomfortably. The three kids didn't move as the professor helped the convict back to his feet, proving what Harry had told them.

"What…is that thing?" Black rasped as he pointed a shaky finger at the Tardis. Matthew moved protectively in front of it.

"I'm wondering that too but, surprisingly, it's currently towards the bottom of the list of what I want to know," Harry said through gritted teeth, tired of it taking so long. "You better start telling us what happened back then if you've had such a massive realisation."

"Once you see Peter, it'll all make sense," Lupin assured them before his eyes went wide. "Peter! Where is he? Where's the rat?" He began to scramble around, Black doing the same, both wildly frantic. Hermione shouted out as Crookshanks lept from her clutches, diving onto a pile of wood and scratching at it. Lupin took the cue, following the animal's instructions and discovering the rat underneath, attempting feebly to scamper away. Blood was speckled over the wood and its movements were awkward and clumsy. "Thank goodness for your cat, Hermione. If it hadn't caught him earlier and done that damage, Peter might have escaped in the chaos."

"You keep calling him Peter." Harry's tone was angry and seething. They didn't get to act as if this was perfectly normal. "But that's Scabbers! Just the pet of a boy in our year."

"I was trying to tell you before we were rudely interrupted. This is Peter Pettrigrew!"

There was a moment of stunned silence between the trio, before Harry began to laugh. "You're insane! Peter Pettigrew is dead." He gestured his wand towards Black. "You saw to that!"

"I wanted to, mark my words," the gaunt man replied. "But Peter got the better of me."

"Well, that's a lie," Matthew commented. "We heard McGonagall talking about you. Pettigrew was basically bottom of the class, especially in duelling. He couldn't have beaten you."

"We underestimated him. That was always our biggest mistake."

"But there were witnesses!" Hermione joined the argument. "They saw you kill him!"

Black ran a hand over his face and, when it left, his eyes were wild and ablaze. "They saw what he wanted them to see!"

Hermione, defiant as ever, refused to back down. "If you're saying that Peter Pettigre is that rat…then I'm sure you're talking about an animagus, right?" She waited for Lupin to nod his head. "Well, there's another hole in your story then. People would have known if he was one. We did it in class with Professor McGonagall and I did some extra research for my homework assignment. The Ministry of Magic keeps tabs on everyone who has the ability to turn into animals. There's an entire register, detailing what animal they become, their markings…things like that. I was curious and looked up our professor on the register - she was only one of seven registered Animagi in the past century! So Peter Pettigrew can't have been one."

The boys looked at her in amazement at what she could remember and the amount of effort she truly put into her work. Even the two men appeared impressed, Lupin tilting his head towards her. She didn't take it as a compliment, even if she would have loved the acknowledgement only a matter of hours ago.

"You truly are the brightest witch in the school, Hermione," Lupin remarked. "But you've been led astray by the available information. The Ministry has gaps in its scope, gaps it can't account for. Such as there being three unregistered Animagi running around Hogwarts at one time."

"If you're going to tell the story, Remus, then hurry up," Black said, hungrily licking his lips as he stared at the rat his friend was holding. "I've waited twelve years for this and I don't want to wait much longer."

"I understand…but I'm going to need your help…I only know the beginning of the tale…" He pushed a few greying hairs out from his eyes. "I suppose it starts with who I am. You know that I'm a werewolf. Perhaps none of this would have happened if I hadn't been so bitter about that. I was a very small boy when I received my bite. My parents…they tried everything but the wolfsbane potion didn't exist back then. Nowadays, I can take it in the week leading up to a full moon and maintain my mind when the transformation happens. I can curl up in my office, away from everyone, waiting until the moon releases me from its clutches." Subconsciously, he gripped the rat tighter as he spoke. "Before that though, I had no choice but to become a monster. And, therefore, it was unlikely that I would be allowed to attend Hogwarts. Other parents wouldn't want their children being at risk."

Harry listened intently as Lupin moved to sit on the most comfortable pile of rubble. He had no idea where this story was going or what relevance it had to the situation, but he was listening all the same. He wondered if his friends were growing tired of having their wands out but their grips were unwavering as they flanked him. He felt a small warmth spread through him as he realised how far they were going to protect him, even if he still didn't understand how they'd got there in the first place.

"But Dumbledore became headmaster at precisely the right time for me, " Lupin continued. "He was sympathetic to my situation, how it was truly out of my hands. He believed that, as long as precautions were taken, it shouldn't have been a difficult choice. This place…the Shrieking Shack…it was constructed solely for my own benefit. People claimed that it was haunted because they could hear my pained screams once a month. The tree and tunnel you came through, Harry, were designed to keep people away when I became dangerous."

The only other noise as Lupin spoke was the squeaking rat as it struggled to get free. Harry wished the stupid thing would be quiet, as if it were ruining the atmosphere. He didn't believe that it could possibly be this Peter Pettigrew, but that didn't mean it couldn't have some manners.

"My transformations back in those days…they were terrible. You can't even imagine how painful it is to turn into a werewolf. Because I was purposefully separated from other people, I resorted to biting and scratching myself. The resulting cries must have been why the rumours began about this place, not that Dumbledore considered correcting them. It helped keep people away. Even when it was empty, people were too scared to come near. It was always better that way. But it wasn't perfect. Because some people decided they still wanted to get close to me, despite everything I was." He looked over at Black with something akin to fondness. "And, it was because of that, that I'd never been happier. Regardless of the pain and the torment I was subjected to, I had friends. Three wonderful friends. Sirius, here…Peter Pettigrew…and your father, Harry, of course, James Potter."

Harry nodded his head silently. Obviously, he'd discovered Lupin's relationship to his dad. He'd wanted to ask him about it every time they saw each other, though politeness had usually prevented him from doing so. But he was wary now, conscious of the possibility that Lupin was invoking his dad's name to appeal to him, to soften him up, to catch him unawares. He didn't allow himself to smile or show any emotional reaction, not wanting the professor to think he was winning.

Lupin carried on, unperturbed. "Those friends couldn't ignore the fact that I disappeared once a month at roughly the same time. I made up so many stories, claiming that my mother was ill and I had to look after her. I was constantly petrified of them figuring out the truth and abandoning me. But, when that happened, they did completely the opposite. It somehow brought us closer together. There was one thing that they could do to make my transformations more bearable…they became Animagi."

"My dad was an Animagus?" Harry asked in shock. Matthew seemed to clutch his arm, as if to remind him not to get sucked in. There was something about the soft way Lupin spoke that could lull you into a calm state.

Lupin nodded his head. "It took them the best part of three years to master the skill. James and Sirius were brilliant wizards and that was necessary because the process can easily go dreadfully wrong. That's why the Ministry monitors it so closely. Peter needed all the help he could get and they were willing to do so."

"Why would being animals help you though?" Hermione asked.

"I've got another question," Matthew interrupted. "Are we going to get to the point? Or are you stalling for something?"

"I'm nearly there, don't worry," Lupin assured them, not annoyed by the impatience. "As for your query, Hermione…they could simply keep me company as animals when I turned. Surrounded by their presence, I became less dangerous. I would still be a wolf but mentally I would be much calmer. And, now that they could transform, new opportunities were ahead of us. We could leave the Shack and explore the grounds in such depth that I reckon no one else knows as much as we did. That's how we came to write the map, Harry. With James and Sirius being such large animals, they could also keep a werewolf in check."

"You were putting people at risk though," Hermione pointed out.

Lupin hung his head. "Yes, you're right. And that's something that still haunts me to this day. There were near misses, far too many. We would laugh about it, carried away by our own cleverness. I felt guilty too because I was betraying the trust Dumbledore had bestowed upon me. He never knew that I was breaking the rules he'd implemented just for me. He never knew that I had led three students into becoming illegal Animagi. But that guilt would ebb away as soon as we sat down and began to plan our next adventure…"

His expression hardened, as did his tone. "The majority of this year has involved me battling a similar level of guilt. I constantly wondered whether I should tell Dumbledore about Sirius' capabilities, but I would always convince myself against it. Because, telling him that would mean admitting that I'd broken that trust he'd instilled in me. So I convinced myself that Sirius was getting into the school using the dark magic he had learnt from Voldemort…that it had nothing to do with him being an Animagus."

"You really had no idea about it?" Harry asked in a small voice. His arm faltered ever so slightly, something which Matthew quickly noticed.

"Harry," he grumbled in warning. "Remember, this could all be one big, sweet lie. It's a lovely story he's woven but isn't it exactly the sort of thing that you'd want to hear? Where's the proof?"

"You want proof?" Black snarled. "We've got the proof! It's time, Remus! It's time to expose this filthy rat for what it is."

"You expect us to believe that you escaped Azkaban to track down a rat? A rat that looks like thousands of other rats? How could you possibly know it's the one you want?"

Lupin looked flummoxed. "The boy has a point, Sirius. How did you find out where he was?"

Black appeared to have been anticipating the question, for he quickly reached into his dirty robes and pulled out a scrap of paper. A moving image could be seen. Harry recognised the group, the Weasley family, smiling in front of a pyramid. He remembered Ron talking about their holiday boastfully plenty of times in the common room. Arthur Weasley had looked a distinct shade of pink when they'd spoken at the train station.

"Fudge visited the prison and left a copy of his Prophet," Black explained, somehow finding the strength to string a full sentence together. And there was Peter, on one of their shoulders. I recognised him instantly…I'd seen him transform so many times. And they were returning to Hogwarts, that's what the article said…I knew that's where Harry was."

A chill ran down Harry's back at that but he focused on Lupin's changing expression as he lifted the rat up to inspect it. "I don't believe it…his front paw."

Harry edged closer, fighting against Hermione's grip pulling him back. "What is it?"

"There's a toe missing."

"It's so obvious now I think about it," Lupin exclaimed. "He cut it off himself!"

Black nodded his head vigorously, as if he had been waiting for years for someone else to understand. Harry supposed he had. "Just before he transformed. When I cornered him, he yelled for the whole street to hear that I had betrayed James and Lily. He blew up the street before I could curse him, killed everyone within twenty feet of him…and scarpered into the sewers with the other rats. No one knew he was an Animagus and who would believe that convenient fact when I told them?"

"The only part of Peter they could find was his finger," Harry muttered in dawning realisation.

"Rats can just lose their toes though," Hermione quickly intervened. "Crookshanks was definitely causing it some grief. It could have happened during that."

"You're right to mention your cat," Black said. "He's the most intelligent of his kind I've ever seen. He recognised Peter for what he was straight away. And the same happened with me when I was in my dog form. It took a while for him to trust me but, from that point on, he's been helping me."

Hermione was aghast at the implications. "No!"

"He tried to bring Peter to me. When that didn't work, he stole a sheet of passwords to Gryffindor Tower. But then I was stopped…" He gestured his head to Matthew. "Nice shot, by the way. I hope I didn't hurt your shoulder."

"You missed on purpose," Matthew said. It wasn't a question. He was beginning to accept what they were being told.

"I wasn't there to harm anyone other than Peter. It was a harmless, wandless spell I used on you. I've never been able to do much without a wand. Only small things we taught one another for fun in school."

"Harmless?" Hermione practically screeched. "He had to go to the medical wing because of you!" Matthew squeezed her hand with his spare one, grateful as ever for her protective nature.

"Peter got wind of what was happening and ran for it," Black continued, slightly wary of the angry girl. "It's only through the hunting prowess of your cat that we eventually managed to catch him. As you can tell from the blood, Crookshanks…is that what you called him? Crookshanks wasn't going to let him get away again."

Something in Harry snapped. Maybe it was because their stories were going on for so long and he was becoming increasingly bogged down by the details. "I think it's perfectly acceptable for Peter to have wanted to evade you. You were there to finish the job you failed to do twelve years ago."

"You're right, Harry, I was. And that's what I intend to do tonight."

"And who says we're going to let you?" He returned his wand to a fighting stance.

"Don't you see, Harry?" Lupin tried calming him down. "All this time, we thought Sirius had betrayed your parents and Peter tracked him down…but it was the other way around!"

"That's not true!" Harry's wand pointed dangerously at Black. "He was their secret-keeper! He said he killed them!"

Black's face was more gaunt than ever. "I as good as killed them. At the last moment, I convinced Lily and James to change their secret-keeper to Peter. Because who would suspect that they would choose him out of their group of friends? That puts the blame squarely at my feet. The night they died, I went to visit Peter to make sure he was still safe. But he was gone, with no sign of a struggle. I was scared, so scared. I immediately went to your parent's house, only to find it in ruins. I saw…I saw their bodies…and knew what Peter must have done. What I had done."

Lupin put a hand on his shoulder, seeing how difficult this was for his friend. "Enough of this. We have the means to prove everything you've said and force the man responsible to speak of his crimes, not you."

"Do it. Before I kill him as he is."

Lupin raised his wand. Harry and his friends did the same, ready to defend themselves if need be. A flash of blue erupted, forcing Scabbers from Lupin's hand and sending him tumbling to the floor. For a moment, the creature twitched and Harry thought it was going to die there and then. But then its features transformed and twisted horribly, stretching into human appendages until a man was left curled up in a ball, his leg gashed and bleeding. The small man was whimpering pathetically, hiding his face. His movements were as rapid as the rat he'd been, his head twisting around. From what Harry could see, his hair was unkempt and colourless, his face remarkably like a rodent.

"Hello, Peter," Lupin greeted them. The three students didn't know what to do as they observed this new development. Harry felt like he needed a lie down. "Long time, no see."