Just gonna casually leave this here... I own nothing.
Ghosts of the Past (Or How the Loneliness of the Wolf is Sated)
Remus Lupin could not believe his eyes. The map never lies. But surely it must, for the map could not possibly be right. Not this time. Maybe it's me, maybe I've gone mental. Wasn't it just the full moon? It must be lack of sleep. But deep down, he knew what he saw must be true. There was no way it couldn't have been.
Peter Pettigrew is alive.
What did this mean? Is Sirius innocent? It couldn't be. But then, Peter was supposed to be dead. Maybe Sirius was… no. No! Sirius was the traitor, the spy. It was he who handed James and Lily to Voldemort, he who lied to the Order, he who murdered Peter.
Remus paced his office thinking. What do I do? He stopped. Sirius's dot was racing across the map directly to where Harry, Ron, Hermione, and Peter were.
I have to go. As soon as the thought crossed his mind, Remus was running. Time was of the essence, there would be no alerting Dumbledore, no recruiting a fellow staff member to follow. He reached the entrance hall in a matter of minutes, nearly flying down the steps, skidding to a stop. The doors creaked open as Professor Dumbledore entered in the company of the minister of magic and two others, one of them with an axe. There would be no better time to tell the Headmaster what was happening. But…Fudge would come too. Sirius would most likely be killed on the spot. I must go alone…
He nodded politely to the group as they passed him. Pulling his wand from his belt, Remus then ran out the door, sprinted down the stone steps, and took off in the direction of the Whomping Willow. After jabbing the knot on the tree with a large branch and disappearing down the hole, Remus once again took up in a mad dash down the long, familiar passage.
Had he not been in such a rush to reach the Shrieking Shack, he would have reflected that the passage had not changed at all in the twenty odd years of its existence.
Finally bursting into the shack Remus paused as a rush of old memories flooded his mind. A voice calling out from the second floor jolted him back to the present and he pounded up the stairs. One nonverbal spell and a sharp flick of his wrist caused the bedroom door to open a bit more harshly than it was meant to, a shower of red sparks bursting from his wand. Remus leapt into the room immediately taking stock of what he saw.
Where is he? There's Ron on the floor, I wonder what happened to his leg? Where is he? There's Hermione, I hope the door didn't startle her too much when it burst open. Where is he? There's Harry… pointing his wand… at Sirius…
And suddenly Remus Lupin was fifteen again.
"Remus! Mate! You'll never guess what happened!" Sirius Black called excitedly as he entered the Gryffindor common room with James Potter and Peter Pettigrew following closely behind.
"Did James humiliate himself in front of Lily again? How'd it go down this time?" Remus said with a laugh as he set down the book he had been reading.
"No, even better!" Peter squeaked pushing Sirius aside, his face stretched into the biggest smile Remus had ever seen. Sirius then tackled the shorter boy for pushing him. James and Remus watched the fight in amusement.
"Sirius is right, you'll never guess what happened," James said with an excited smile. "Come on, let's go up to the dorm and we'll tell you." At that, Sirius and Peter's fight ended, with Sirius pushing Peter once more for good measure.
"Alright, sit here Remus," Sirius sat as he pushed his friend onto the trunk James had pushed into the center of the room. He was practically bouncing out of his shoes. "Are you ready?"
"As I'll ever be I suppose."
"Alright! Me first, then Pete, and James, you last because you're the biggest." Remus sat, confused over what Sirius said. James was not nearly the biggest of the four. His confusion was short lived, however, as Sirius started transforming right before him. He rubbed his eyes, to make sure what he was seeing had actually happened, and when he uncovered them in the next moment, three animals stood before him. The black shaggy dog that had been Sirius cheerfully bounded over to his friend, his tail wagging rapidly.
Remus was dumbstruck. "You… you did it?" he asked hesitantly. Peter, in his rat form, squeaked in affirmation and James bowed his antlered head as if to nod. "You actually… did it. You actually did it!" Remus shouted, pure happiness coursing through him as he wrapped his arms around Sirius, hugging the dog tightly.
One by one, the boys changed back into themselves, each with a huge smile plastered on his face. "So you absolutely hate it then," Sirius stated, trying to reign in his smile.
As he stared at his friends, Remus found he couldn't speak. Instead, he held out his arms and the three tackled him.
Remus had never looked forward to a full moon. That said his first transformation with the rest of the Marauders was the best of his life. It's true that it didn't hurt any less, and as usual he didn't remember it the next morning, but when he woke up in the Shrieking Shack, behind the aching and tiredness there was a feeling of contentment in his bones.
By the end of their fifth year, Remus could not imagine going through a transformation without his friends ever again. So, it was understandable that during the last couple days of the year, he was increasingly depressed.
"What's the matter, Moony?" Sirius asked on the Hogwarts Express. Remus had barely touched any of their snacks, and the full moon was in a week.
"Oh, nothing. I'm just not hungry, is all."
"Bullocks to that!" Sirius exclaimed.
"Hey Moony, Wormtail and I were figuring we'd floo to your house next week… er for a sleepover?" James interceded, sensing Sirius was about to make a scene.
"I wish I could be there," Sirius moped.
"You'll be there in spirit, Padfoot," Peter replied, patting him on the back.
Sirius huffed. "I am not looking forward to summer break."
"You never look forward to summer," Remus replied. "But then again, neither do I."
"Yeah, but this year you have us!" Peter said with a grin. His smile was infectious and soon all four boys were smiling and joking like usual.
"So I'll see you next week, then?" Remus questioned James and Peter, as their parents chatted amiably on the way out of King's Cross. Sirius had already left with his parents by side-along apparition. The boys had learned early on to say their goodbyes to him on the train.
James reassured his friend that "Of course we'll be there, stop worrying." With Peter adding that they were "looking forward to it."
The next week was one of the slowest Remus had experienced. But time did pass and soon enough it was the day of the full moon.
"Remus, old chap! It's been too long. Too long!" Sirius called as he barged into the room.
"Sirius? I... It's only been a week. How did you-?"
"James'll be on his way in a few minutes. So this is your room, eh? Very nice. But an Appleby Arrows poster? Really, Moony? The Catapults are a far superior team. The Arrows have no defense! Even the Cannons have a better defense than the Arrows."
"Sirius!" Remus shouted, succeeding in interrupting his friend's chatter. "How'd you manage getting your parents to agree to let you come over?"
"I- er, good news, Moony... It seems as though I am officially no longer a Black," Sirius said with a grim smile and a bitter laugh. "The Potters have been gracious enough to take me in. I think they always secretly wanted me as a son."
"Sirius, I-" Remus stopped, seeing the pain in the stormy grey eyes. "Thanks for being here, Padfoot. It means a lot," he said with a smile.
"Wouldn't have missed it for the world, mate."
That summer, and most of sixth year, flew by for Remus. The boys finally finished the Marauders Map, which they had been working on for most of their time at Hogwarts. They used it constantly and, with the help of James' invisibility cloak, pulled their best pranks yet. All good things had to come to an end eventually, and this time, it came in the form of Sirius pulling a terrible prank on Snape once everyone was back from winter holiday.
A few days after the prank gone wrong, James finally forced Sirius to tell Remus what had happened. The blowup that followed caused a rift between the Marauders, the rest of Hogwarts couldn't figure out why two of the four refused to talk to each other for months. Eventually, at the end of the year, Sirius apologized profusely and Remus grudgingly forgave him, making him promise to never ever pull a stunt like that again.
The rest of Remus' memories flew by in a flash. The Marauders' seventh year. Lily finally accepting a date with James. N.E.W.T.s and graduation. The Marauders and Lily joining the Order of the Phoenix, James and Lily's wedding, the death of James' parents. Finding out Lily was pregnant and then the birth of Harry.
Being in the Order brought paranoia to all the Marauders, they started seeing each other less, Sirius and James thinking Remus was the spy, Remus himself thinking it was Sirius. No one suspecting quiet, little Peter. Finally James and Lily went into hiding and the Fidelius charm was put into place. August of 1981 was the last time Remus saw the Potters.
November 1st, 1981 was the worst day of Remus Lupin's life. Three of his friends were dead and the fourth was in Azkaban for it. He was completely alone, no job because of his "furry little problem", no need for the Order since Voldemort was gone.
And now, now he was facing his old friend. Because Peter is not dead. Three of the Marauders in the same room for the first time in twelve years.
His memories lasted no more than a minute. He came back to himself pointing his wand at Harry, everyone's eyes were on him.
"Expelliarmus!" he shouted, Harry's wand flew through the air into his hand as did the two Hermione were holding. "Where is he, Sirius?"
Time seemed to stand still as the two old friends stared at each other, then, slowly, Sirius raised his hand and pointed at Ron. "But then... Why hasn't he shown himself before? Unless-" Remus' eyes widened. Everything was finally adding up in his mind. "-unless he was the one... unless you switched... without telling me?"
Sirius, his eyes never leaving Remus', slowly nodded. It was never Sirius. It never could have been. James and Lily, he would have died to protect them. Oh god, how blind I was. It was Peter. All along it was Peter.
Remus, lowering his wand, was aware that Harry said something, but what it was he had no idea. He walked over to his oldest friend, extending his hand to help him off the floor. When Sirius was on his feet, Remus embraced him. Sirius, I'm so sorry. How I've missed you old friend.