Harry looked at Lupin. He didn't understand what he was talking about. Around him, Ron and Hermione were looking quite bewildered. Slowly, Black raised a bony hand and pointed at Ron.

"But then…" Lupin murmured, staring at Black so intently that it seemed he was trying to read his mind. "Why hasn't he shown himself before now? Unless—" Lupin's eyes widened, and he suddenly came to a conclusion. "Unless he was the one…unless you switched…without telling me?"

Very slowly, Black nodded.

"Professor!" Harry interrupted. "What's going on…?"

But he never finished his question, as before his eyes, Lupin lowered his wand and hugged Black like a brother. Immediately, the cogs in the guard's head began to turn.

"Jinchuriki!" The guard screamed, while taking out Harry's kunai from the wall and letting it rest a hair's breadth next to Lupin's throat. "All this time...You…" He swallowed slightly. "Your smell…"

Lupin jerked back, and by reflex, Kakashi cut his throat slightly that a ruby red drop of blood dripped onto the black metal.

"How long have you known..?" Lupin asked the guard. "How long have you known that I'm…"

Now it was Hermione's turn. She gasped in shock and began pointing a finger at Lupin.

"Y-you…" She gasped as Lupin tried to step forward.

"You've been helping Sirius Black into the Castle! You're his friend! YOU'RE A WEREWOLF!" Hermione screamed.

Silence followed, and then the guard hissed in his own language. "Bakemono…" He spat the word out with so much loathing that it could've melted rock. He dug the sharp edge of the kunai closer to Lupin's throat. "You're a demon…a monster."

"How did you know?" Lupin asked Hermione. "As far as I know…I have never told you to do anything concerning werewolves…" He was prevented from moving as Kakashi dug the knife deeper, causing the blood to flow.

"I borrowed a book…Professor Hatake told me I could…" She whispered fearfully.

"You're the cleverest witch of your age, Hermione." Lupin praised, albeit forced.

"No…I'm not. If I had been a little cleverer, I would've told everyone what you were!" Hermione replied.

"The staff know what I am…" Lupin replied. "Although the guards do not seem to know." This he directed at Kakashi, who narrowed his eyes behind the mask.

"If I had known, I would've killed you by now…Bakemono" Kakashi replied with malice. "Dumbledore was right to hide it from me."

Lupin blinked. "Why?" Curiosity was overcoming him.

"BECAUSE ONE OF YOUR KIND DESTROYED MY LIFE, MURDERED MY TEACHER IN FRONT OF ME AND TOOK AWAY EVERYTHING I WAS TRAINED TO DEFEND!" Kakashi finally burst. All the locked up emotions formed into a tsunami of pain and hate and hit Lupin like a punch to the face.

Lupin's eyes widened in horror. "That's…but I…"

"Bakemono." Kakashi spat out, drawing back his arm to strike Lupin. A millisecond later, he launched himself at the surprised werewolf, leaving Ron in Harry's keeping as a shocked Black attempted to separate the enraged guard from the shocked werewolf, who was trying to defend himself.

This was not doing much good.

Harry pointed his wand at the struggling people, unable to get a clear shot.

Finally, Black had managed to separate the two of them. Lupin was sporting a black eye and a cut lip while one half of Kakashi's mask had been shattered. His closed left eye was slightly bruised.

"How did you know he was here?' Hermione asked, breaking the silence.

"The map…" Said Lupin, relieved for a change in topic. "…The Marauder's Map. I was in my office examining it..."

"You know how to work it?" Harry asked suspiciously.

"Of course I know how to work it. I helped write it." Lupin said, waving a hand impatiently. "Sirius, it's time."

Sirius nodded and explained everything. How Lupin was bitten, how they had managed to turn into Animagi. How James was a stag, Peter a rat, and Sirius a dog. How they explored every inch of Hogwarts and how they made the map and signed it.

Finally, Black turned to the supposed murder of Peter Pettigrew.

"Everyone thought I killed Peter." Sirius said, with Lupin nodding. "He confronted me in a street full of Muggles, yelled out that I had betrayed Lily and James for proof, and then he cut his finger, and blew the street with his wand behind his back, turned into a rat and headed down the sewer."

"I believed it myself, until I saw the map." Lupin supplied. "The Marauder's Map never lies. Peter's alive, Ron's holding him Harry."

"Ron, if you want this thing to be done, give me Scabbers." Lupin said, holding out his hand.

Ron held Scabbers close to his chest. "Why?" He asked.

Lupin held his wand aloft. "If he's a real rat, this won't hurt him."

After a while, Ron agreed. The bedroom door creaked open suddenly. Kakashi had his right eye on it, but it appeared that the door creaked open of its own accord.

Soon he didn't pay attention to it either as Lupin finished his tale.

"…forbidden by Dumbledore to tell anybody, but from that time on, he knew what I was…."

"So that's why Snape doesn't like you," Harry said slowly. "…because he thought you were in on the joke?"

"That's right." A cold voice sneered from the wall behind Lupin, his upper body visible as Snape pulled the cloak off.