Remus took the map, and the spare wand he had stolen from the Room of Requirement, and ran. He picked up Harry's invisibility cloak at the mouth of the Willow and sped toward the Shrieking Shack.
The scene was just as he remembered it from five years before— he hadn't noticeably damaged this part of the timeline, at least.
But that was going to change. For the better. Good damage. Good damage only. Lives saved. Wrongs righted. Injustices washed away.
This was not the time to ponder whether his plan was delusional, not with the full moon rising, dementors swarming the castle grounds, Peter plotting his escape, Ron lying on the floor with a broken leg, and Harry aiming his wand at the heart of a broken-but-not-beaten Sirius.
Merlin, the absence of Sirius had settled into Remus' being like a permanent physical ache.
But it was Peter he needed to get under control, and right now.
"Where is he, Sirius?" Remus asked quietly.
There was a long pause— had it taken this long the first time, or had Remus just been busy figuring out what in the name of everything magical was going on?— before Sirius pointed at Ron.
"Ron," said Remus in his most professorial voice, "Do you think I could have a look at your rat?"
"What's Scabbers got to do with it?" demanded Ron.
"Everything," said Remus.
"The man who killed Harry's parents and escaped from Azkaban is right there, and you're worried about a rat?" Ron asked.
"Precisely," said Remus.
"Don't do anything he asks," suggested Hermione from where she'd been hovering in the shadows. "Harry, maybe you'd better—"
"Maybe you'd better lower your wand," Remus interrupted. He really didn't want to disarm the children this time around; he knew perfectly well that Harry wasn't going to murder anyone, not even the man believed to have betrayed his parents. In the future-past, Harry had eventually gotten to the point where Remus had wished he'd been willing to cast a spell more aggressive than Expelliarmus once in a while. "You don't want to hurt someone by mistake."
"If I hurt him, it won't be by mistake," growled Harry.
"If you were going to kill him, you'd have done it by now. Why not listen to what he has to say, what we have to say, and if you still want Sirius dead half an hour from now, I imagine he'll hand himself over to you."
"What can you possibly have to say that would make me change my mind?"
"Lower your wand." Harry did so begrudgingly. "And you," Remus added, turning his attention to Ron. "Hold onto the rat. If he moves, I will stun him."
"That's all you're planning to do? Stun him?" Sirius demanded.
"I'd like to have him testify before the Wizengamot, and he can't do that if we've killed him, as tempting as that may be."
Wormtail gave a squeal and wrenched himself out of Ron's grasp. "Petrificus Totalis," Remus snapped. Wormtail froze.
"When I suggested not stunning him, I didn't mean body bind him instead," muttered Sirius.
"If I'd stunned him, he might not have heard what we have to say. I think he needs to hear what we have to say, don't you, Padfoot?"
"Padfoot…" murmured Harry thoughtfully.
With Peter immobilized and the children, at least for the moment, willing to listen, Remus turned to the business of scraping Sirius off the ground and pulling him into a hug. Sirius laughed a little, and Remus was forcibly reminded of the last time he'd seen Sirius alive. Laughing then, too, of course. "Come on! You can do better than that!" he'd taunted Bellatrix, his voice echoing around the room as the jet of red light caught him in the chest.
Remus gripped Sirius more tightly and forbade the tears to come to his eyes. Sirius returned the hug and dropped his head to Remus' shoulder, just for an instant. Sirius was giving himself over to Remus, but not for long, not all the way.
"Don't see why you're so set on letting the Ministry screw things up again."
"I am set on keeping you alive, free, and with your soul attached to your body," Remus answered. "Easier with a live witness." He gave Sirius a final squeeze before letting him go and turning to address Harry, Ron, and Hermione. "We have less than half an hour and there is a lot that we need to explain to you, so please pay attention."
"Why do we have less than half an hour?" asked Sirius. "If there's some kind of deadline, I want to kill him now."
"The moon is full," Remus reminded him. Sirius' skeletal hand briefly brushed the back of Remus' neck in sympathy.
"They want my pet rat to testify before the Wizengamot, and we can't talk for more than twenty minutes because the moon is full. Am I the only one who realizes they're both mental?" Ron asked Harry and Hermione.
"The full moon is a problem because Professor Lupin is a werewolf," Hermione told him. Harry and Ron both jumped, and Hermione looked hard at Remus. "I hope your explanation was going to include that."
Remus nodded. "It's going to begin with that."
"Why are we listening to an escaped prisoner and a werewolf?" Ron demanded, more loudly.
"He's a very good professor, though," said Hermione. "The first decent Defense Against Dark Arts professor we've had. We learned loads for once, and that's the class we need the most, you know. And werewolves aren't dangerous if they take Wolfsbane Potion properly, which I imagine Professor Lupin has."
"Yes," Remus confirmed. "I have, but I'd still rather not have you anywhere near me when I transform."
"I think it would be fascinating."
"That's what concerns me."
"How did you know he was a werewolf?" Harry asked Hermione.
"He always gets sick around the full moon, and when boggarts see him they turn into the moon."
"Hermione is very clever," Remus told Sirius needlessly. "Thank you for not telling anyone," he added in Hermione's direction.
"I'm not sure I was right," she answered tightly.
"Then let me explain." Sirius and Ron were both glowering at him, both ready for the talking to be over. He told the story more smoothly and succinctly than he ever had before. His unexpected admission to Hogwarts. Being swept up in a friendship with the two most popular, powerful boys in his year. The Animagus transformations. The long nights in the woods. The rift created by Sirius' prank, and the utter loathing Severus Snape bore him to this very day. The last-minute Secret Keeper switch, and Peter Pettigrew's betrayal of his friends.
He let Sirius take over and describe recognizing Peter's rat-form, complete with missing toe, in the Daily Prophet and escaping with the goal of protecting Harry.
"Show us," said Harry. "Show us that Scabbers is really Peter Pettigrew."
"Gladly," rasped Sirius.
Remus flicked the spare wand at Sirius, who caught it deftly. On the count of three, they forced Wormtail from his transfigured state.
Remus' stomach turned as he looked at the man before him. "Hello, Peter. Long time, no see."
Peter didn't even bother trying to make a case to Sirius, not that Remus blamed him. "You don't believe him, do you, Remus? He tried to kill me! He's come to try and kill me again! He killed Lily and James, and now he's going to kill me too!"
"No one's going to try and kill you," said Remus. "We considered it, but we'd much rather have you alive to prove that Sirius is innocent."
"Sirius, innocent? He was Lily and James' Secret Keeper! You knew that! Everyone knew that! James trusted him above all others! If they changed the plan, he would have told you!"
"Not if he believed I was the spy," said Remus quietly. That still hurt.
"Why would he believe such a thing?"
"Forgive me," Sirius interrupted, ripping his gaze from Peter for the first time. "Please forgive me, Remus."
(And they said Blacks didn't apologize.)
"Not at all, Padfoot," said Remus. It hurt, but he had long since forgiven Sirius. "And will you forgive me for believing you were the spy?"
"Of course," said Sirius.
(And they said Blacks held grudges until the end of time.)
"But why would you have thought Professor Lupin was the spy?" Harry asked, looking earnestly at Sirius.
Remus didn't give Sirius a chance to answer. "I told you that I was surprised to have friends when I came to Hogwarts. I was stunned when they discovered my secret and decided that we were still friends. I was so grateful… I was so disbelieving… that I could never argue with James or Sirius when I thought they were wrong. I told you, Harry, months ago about why I was a prefect and your father was not."
Beside Remus, Sirius made a rough sound in his throat, as if he were caught between reliving an old joke and grieving for a tragic misjudgment.
"The whole truth," Remus continued, "is that Professor Dumbledore wanted to see if making me a prefect would allow me to exert some control over James and Sirius' more… dangerous antics."
"That wasn't why. He was rewarding you for being a good boy, same as every other prefect in the history of the school."
"In any event, James and Sirius did things that any prefect should have told them to stop, and I didn't. Sirius knew I couldn't stand up to him, and Sirius assumed I couldn't stand up to Lord Voldemort either. And because Peter is not stupid, he did everything he could to sway Sirius' opinion without Sirius even realizing it. Correct, Sirius?"
Sirius nodded.
Harry looked sympathetic. "Professor Dumbledore says that standing up to your friends takes as much bravery as standing up to your enemies."
"I'm glad you know that already," said Sirius. "Bit of a nasty shock for me, the way I learned that particular lesson. I mistook obsequiousness for loyalty and fear for cowardice." He glanced at Remus again. "You seem just fine with ordering me about now." He pointed at Peter. "You're sure you won't let me kill him?"
Remus rolled his eyes. Peter cringed.
"Do you three have any other questions for Peter before we stun him and bring him up to the castle?" Remus asked the children.
"I let you sleep in my bed!" exclaimed Ron. It wasn't precisely a question, but Remus agreed that Ron had every right to say it.
"I was a good friend! A good pet! You're a kind boy, you should believe me when I—"
"If you made a better rat than a human, Peter, that isn't much to brag about!" Sirius snapped.
"And it does beg the question of why an innocent man would choose to spend twelve years as a rat," Remus agreed. He glanced at Ron. "Or why, when you told your rat that he was invited to Professor Lupin's class the next day, he suddenly vanished as if he'd understood you even though he never ran off."
Ron nodded, pale with the memory.
"You suspected?" Sirius asked Remus sharply.
"I did, but without proof I had absolutely no chance of convincing anyone else." He turned his attention to Hermione. "You're quiet, Hermione. Any objections to taking Sirius and Peter to the castle? Any questions?"
"How are we going to get Mr. Pettigrew back to the castle without him transforming and running off, and how are we going to get Mr. Black inside the castle when the doors know not to let him in, and how are we going to avoid the dementors, and how are we going to make sure those horrible Ministry people who killed Buckbeak will listen to us?"
"Excellent questions, Hermione," said Remus.
"She your favorite student, Professor Moony?" asked Sirius, sounding almost amused.
"Harry's his favorite," said Hermione quickly.
"That's different," said Ron. "He's known Harry since he was born."
"With the unfortunate twelve-year gap in between," modified Remus. "I'm going to stun Peter hard enough that he won't wake up until well after you've reached the castle."
"No!" objected Sirius. "If you won't let me commit the murder I've been imprisoned for, you can at least let me stun him."
"We'll stun him together," agreed Remus cooly. "Make sure it takes."
Sirius wordlessly raised his wand, and Remus followed suit. At their unified "Stupefy!", Peter collapsed to the floor.
"Now," said Remus to Hermione. "Your next question. Sirius will be able to pass through the doors because Sirius will be invisible." He pulled Harry's cloak from beneath his robes and passed it to Sirius. Sirius' eyes brightened at the sight of the cloak. "Be more careful with that in the future, Harry. Anyone could pick it up if you drop it, and you won't find it easy to replace."
"The dementors will still be able to sense him even if he's invisible," said Hermione.
"And that is why Harry is going to walk out of the tunnel first. Harry, I want you to cast your Patronus before you even step out of the tunnel, whether you see dementors or not. You know how much harder it will be if you start to feel their effects before you try to cast the spell, and there's no guarantee that Sirius will be able to cast magic that complex with a wand that isn't his."
"Right," agreed Harry.
"Hermione, you can cast mobilicorpus and float Mr. Pettigrew back to the castle?"
Hermione nodded.
"And Ron," Remus concluded. "Your job is to go straight to Madam Pomfrey and let her mend that leg for you. I'll bind it well enough for you to get to the hospital wing. Ferula."
Ron stood and gingerly tested his weight on his broken leg. "Thanks," he said.
Remus nodded briskly as a shudder ran down his spine. "Now. Go. Harry first, then Hermione with Peter, then Ron. Ron, keep your wand on Peter and do whatever you have to do if the stun wears off."
"Believe me, I will."
"Sirius, stay invisible and stay behind them."
"You really don't have a problem telling other people what to do anymore, do you?"
The next shudder was more emphatic, more frightening. "Go!"
"Stay safe," murmured Sirius quietly, and he went.
Remus ripped off his clothes and huddled into himself, straining to hear the footsteps retreating down the tunnel until the transformation took hold.
When the pain and confusion was over, even the wolf's sharp ears heard nothing.
He could only wait and hope.