"Professor Lupin, Harry and the others are currently very- Er- tense right now. I think it would help if you returned our wands back."
Professor Lupin stared at Arth blankly before letting out a sigh.
"I suppose you are right."
He threw each wand back to its owner.
"There," said Lupin, sticking his own wand back into his belt. You're armed, we're not. Now, will you listen?"
"I hope we can-" said Arth giving a quick glance at Harry, "-now that we are in a more advantageous situation..."
Of course, Arth couldn't mention the fact that most wizards could cast windless magic. There was simply no point.
"If you haven't been helping him," Harry said, with a furious glance at Black, "how did you know he was here?"
"The map," said Lupin. "The Marauder's Map. I was in my office examining it —"
"You know how to work it?" Harry said suspiciously.
"Of course-"
"Wait a minute," interrupted Arthur, "You got the map confiscated by Lupin, Harry?"
"...yes."
"...you are so stupid Harry. How did you even lose the map? All you had to do was- you know what, I don't care anymore. Please continue."
Lupin gave a weird look at Arthur before continuing.
"As I was saying, of course, I know how to work it," said Lupin. "I helped write it. I'm Moony — that was my friends' nickname for me at school."
Arth's mind did a triple hand back spring. Professor Lupin was one of the people who made the map! How incredible!
"You wrote — ?"
"The important thing is, I was watching it carefully this evening because I had an idea that you, Ron, and Hermione might try and sneak out of the castle to visit Hagrid before his hippogriff was executed. And I was right, wasn't I?"
He had started to pace up and down, looking at them. Little patches of dust rose at his feet.
"You might have been wearing your father's old cloak, Harry —"
"How d'you know about the cloak?"
"The number of times I saw James disappearing under it..." said Lupin, waving an impatient hand. "The point is, even if you're wearing an Invisibility Cloak, you still show up on the Marauder's Map. I watched you cross the grounds and enter Hagrid's hut. Twenty minutes later, you left Hagrid and set off back toward the castle. But you were now accompanied by somebody else."
"What?" said Harry. "No, we weren't!"
"I couldn't believe my eyes," said Lupin, still pacing, and ignoring Harry's interruption. "I thought the map must be malfunctioning. How could he be with you?"
"No one was with us!" said Harry.
"And then I saw another dot, moving fast toward you, labeled Sirius Black... I saw him collide with you; I watched as he pulled two of you into the Whomping Willow —"
"One of us!" Ron said angrily.
"No, Ron," said Lupin. "Two of you."
He had stopped his pacing, his eyes moving over Ron.
"Do you think I could have a look at the rat?" he said evenly.
"What?" said Ron. "What's Scabbers got to do with it?"
"Everything," said Lupin. "Could I see him, please?"
Ron hesitated, then put a hand inside his robes. Scabbers emerged, thrashing desperately; Ron had to seize his long bald tail to stop him escaping. Crookshanks stood up on Black's leg and made a soft hissing noise.
Lupin moved closer to Ron. He seemed to be holding his breath as he gazed intently at Scabbers.
"What?" Ron said again, holding Scabbers close to him, looking scared. "What's my rat got to do with anything?"
"Oh come on Ron, could it be any more obvious?" Said Arth scornfully. "Literally all of the clues are right in front of you making a beacon and yet you are still oblivious to it."
"That's not a rat," croaked Sirius Black.
"What d'you mean — of course, he's a rat —"
"No, he's not," said Lupin quietly. "He's a wizard."
"An Animagus," said Black.
Arth then followed up and said, "a person who was thought to be dead by the entire world, a person by the name of Peter Pettigrew."
Boring chapters are a necessity for those who have not read the original books