*Harry Potter of course belongs to Ms. Rowling. I quote a few lines from POA in this story. I've marked the quotes with an asterisk and attribute them to the source.
Remus slowly climbed up the stairs leading to his office trying not to groan aloud. His muscles ached more the closer to the rise of the full moon. Now, only a few hours before nightfall, he felt as though he'd been trampled by a herd of thestrals.
Walking into his office, Remus was greeted by clamorous smack and a splash of water in his face.
"Good evening, Gorky. Excellent aim, as always." Remus smiled as he wiped off his face with a handkerchief. In response, the grindylow displayed a spindly middle finger, with a sharp claw angled ominously toward Remus. "Now, now...if I were you, I'd keep up at least a veneer of politeness until after I feed you." He waved his wand and the cupboard door next to the tank opened. A heaping cupful of small, silvery fish arose out of a bowl and floated over to the grindylow's tank.
Remus listened to the grindylow's chomping as he sat down at his desk. Hagrid gave him the grindylow at the beginning of the year to use for his lessons. He planned to release it after the lesson, but found his presence surprisingly pleasant. Unlike some of his fellow staff members who scurried away, eyes focused on the ground, every time he entered a room, Gorky was a captive audience. Even its leers were endearing, rather like his uncle's old parakeet who gleefully chirped swear words and Shakespearian insults at every passerby. It was probably best that Gorky couldn't speak.
A tarnished silver goblet stood at the corner of the desk. It was full to the brim with a viscous, puce liquid out of which rose perfect O shaped puffs of steam every five seconds. Remus wrinkled his nose at the odor. It reminded him of rotting grapes and dog droppings. Unfortunately, it tasted even worse than it smelled. He pushed the goblet into a far corner of the desk. He wouldn't need to take it for at least two more hours.
Severus must have dropped off the potion on his way to dinner. Remus could imagine the sneer twisting across Severus's face as he walked into the office he desperately wanted for himself. How humiliating to be coerced to help the man who not only took the job he wanted but was also an avowed enemy since the days of boyhood. Severus had never grown out of his angry schoolboy mentality. Remus half expected the Wolfsbane potion to be botched, full of Snape spit. But no...the potion was prepared perfectly every full moon. Perhaps Severus was motivated by respect for Professor Dumbledore or by pride at being able to master a remarkably difficult potion. Then again...Remus gazed warily at the cup out of corner of his eyes...if it was possible to do so without disturbing the potion's efficacy, Severus probably had spit in it.
It was fortunate that the full moon was at the end of term. He would miss very little. The grading was done. Remus had stayed up until 3 AM the past four nights making sure everything was finalized. All that was left to do before summer break was a few letters to parents and his end of term report to Professor Dumbledore. Nothing that needed to be done immediately.
Only one task remained for the evening. Remus hoped, but rather doubted it would be a boring, uneventful one. He pulled open the top desk drawer and took out a worn, folded up piece of parchment. One look at it and his stomach lurched and he could scarcely breathe. The Map had sat in his drawer since he confiscated it from Harry. Remus couldn't bear to look at it. The Map was full of memories that had once been happy - a symbol of years of teamwork, laughter, friendship, and mischief - but life had twisted the memories into a mixture of betrayal, grief, shame, and regret.
He remembered the night they began the Map like it was yesterday. Sirius came storming into the Gryffindor Common Room, soaking wet and shaking with fury.
"Never again," Sirius growled, throwing himself onto the sofa next to James and ringing out his robes with a towel he summoned from upstairs.
"What'd Filch make you do, give the giant squid a sponge bath?" James asked.
"I wish. He made me clean all the toilets and sinks in the boy's bathroom on the first floor with a toothbrush. Took me two hours!"
Remus eyed Sirius's dripping hair and grinned. "And did you think the toilets would be easier to clean if you were standing inside them?"
Sirius rolled his eyes. "Snivellus snuck in when I was doing the sinks. Someone must've told him I was in there. He jinxed the faucet so it exploded all over the room. Made sure he regretted it though."
"What'd you do, Sirius? What'd you do to him?" Peter squealed.
"Pretty much what he did to me, only a thousand times better. Pushed him into a stall and made the toilet explode in his face. The one Davey Sears was sick in after dinner." Sirius waggled his eyebrows. "Honestly, I think he looked better covered in barf. Maybe we should keep him covered in it."
Scowling again, Sirius jumped up and started pacing in front of the sofa. "I'm sick of getting detention every time I feel like going for a walk." James started to speak but Sirius interrupted him. "I know I can borrow your cloak whenever I want, but that's not the point. We can't all use the cloak all the time. What we need is some kind of alarm that goes off anytime Filch or a teacher or a Slytherin gets near."
Remus set down his Potions book and grabbed a piece of parchment from the table. "What about a map?" He sketched a crude drawing of the castle. "We can do a collocatem charm to show where all the teachers are." He added dots randomly around the parchment.
"Genius, Moony!" James kneeled next to the table and grabbed the parchment. "I think we should make sure that everyone in the castle shows up on the map. After all, you never know who you might want to find," he said, with a slightly dreamy look on his face.
"No one needs a map to find Lily, James." Sirius snorted. "All we need to do is follow the trail left when you drool after her." James punched Sirius playfully. Sirius shoved him back and threw a pasty in his face. By the time they were ready to go to bed, Sirius, Peter, and Remus were covered in pumpkin juice and James had pieces of treacle tart stuck to his hair. But the idea of the map remained.
Almost twenty years later, the creation of four friends was left in the possession of the only one who remained living and free. Remus's stomach twisted as he ran his hands along the smooth parchment. But it was time to put personal feelings aside. If ever there was a night that Harry would sneak out of the castle, it would be tonight. He was sure Harry would insist upon consoling Hagrid upon his hippogriff's execution. Did the boy understand just how dangerous the castle grounds might be for him? Remus thought that he probably did. As much as he wanted Harry to be safe, Remus couldn't help but be proud. Harry was the kind of boy who broke rules not just for the sake of mischievousness, but to help his friends. James at seventeen would have done the same, but perhaps not James at thirteen. Harry was the best of his mother and father.
Remus tapped the map and whispered the words that Sirius had thought up so many years ago. "I solemnly swear that I am up to no good." Ink spread out like a spider web as the map slowly came into view, along with his friends' cheeky greeting. The handwriting, as well as the drawing, was Peter's work. It was his only contribution to the map, since he never could do the charms correctly. Peter begged and begged them to let him help somehow. Since Peter was the best artist of the four of them, drawing the actual map was the perfect job for him.
Remus searched the map looking for Harry's name. He drew a circle with his wand along the grounds near Hagrid's cabin and the map zoomed in, making it easier to read the names underneath the dots. Sure enough, Harry, Hermione, and Ron were edging towards Hagrid's.
Was now the time to go after them? Remus didn't want to get Harry in trouble. Or have to explain how he knew where Harry was. Hagrid would keep them safe and Dumbledore would be there soon for the hippogriff execution.
For lack of anything else to do, Remus pulled out a sheet of parchment and started writing to the parents of one of the students who failed the exam. "Dear Mr and Mrs Crabbe..." His quill rested on the parchment, soaking it with ink. He was looking back at the map so often that he couldn't focus on writing the sensitive yet firm letter he'd planned on. At one point he came close to writing, "Your son is duller than a flobberworm and meaner than an acromantula," before remembering that that was a sure way to get fired. He stared at Harry's stationary dot in Hagrid's cabin and imagined James, Sirius, and Peter roaring with laughter at Crabbe's expense. His stomach gave another lurch. This was why he'd avoided looking at the map. All it did was force the memories he'd worked so hard to forget back into his mind.
He threw his wand onto his desk in frustration. It hit the map exactly on Hagrid's cabin and zoomed in even closer towards it. Remus sighed, picked up his wand, and was about to zoom out to a normal view of the castle when he saw movement. Harry, Ron, and Hermione were just outside the cabin. He breathed a sigh of relief as he saw them moving closer to the castle. Then he noticed a fourth dot, nearly on top of Ron.
His jaw dropped. "Peter," he gasped, staring at the name written in small, tight calligraphy. "Oh my god, Peter!" he shouted. Remus pushed back from his chair so fast that it hit the wall and he fell out of it. His knees slammed to the ground and his head smacked the desk making stars leap in front his eyes. From the floor, he grasped at the desktop until he found the map and smashed his wand onto it, poking at Peter's dot so hard that he would have put a hole in the parchment if they hadn't put an non-lacerandus charm on it. He zoomed into Peter until the dot was the size of a snitch.
"It can't be. I don't believe it," Remus whispered. The map had never been wrong before. Maybe the charms were weakening with age. But why would Peter's name show up, of all names? He thought back to all the charms they put on it. He'd done the veritas and perpetua charms himself. They were perfect. He was sure of it. It had to be Peter.
But why? Why would he show up now? Why with Harry and his friends? Remus rubbed the growing lump on his head and watched the dots move closer to the castle then jerk to a stop. Peter started to separate from the trio. How could a strange man, let alone a presumed dead man, get into the castle grounds undetected? Remus knew the answer immediately. No one would notice a rodent.
He'd get Dumbledore. Explain everything and together they could go to Peter. Maybe Dumbledore already knew he was there. Then he saw a new dot appear moving swiftly towards the group. It was like a punch to the stomach. Sirius. All the ghosts whose memories haunted him converging at Hogwarts tonight. He blinked thinking, hoping his eyes were playing tricks on him, but all the dots remained. Sirius had collided with Harry, Peter, and Ron. Peter, Ron, and Sirius were now moving towards the whomping willow, leaving Harry and Hermione behind.
Remus leaped up, slammed the map onto the desk, and ran out of his office. He had to find them. Thoughts flowed through his head even faster than he could run. He should tell Dumbledore. There was no time to tell Dumbledore. He was afraid to tell Dumbledore. What was Sirius going to do to Peter and the kids? What was Peter going to do to Sirius and the kids? How was Peter still alive? What about Sirius? Might he be innocent? How could he have killed all those Muggles on the bridge but not have killed Peter? Who betrayed whom?
Remus was running so fast that he barely registered his chest screaming for air and his muscles cramping in pain. One foot in front of the other. The whomping willow was in view. He grabbed the first long branch he saw and jabbed at the knot in the tree. He threw himself at the base even before the tree stopped moving and grunted when a branch slammed into his back. Still, he clambered into the tunnel under the trunk. Half crawling, half running, Remus stormed through the tunnel towards the Shrieking Shack, bumping his head again and again. The tunnel felt miles longer than he remembered it.
Finally, he was in the Shack. Gasping for breath, he wheeled his wand around the entryway, searching, but saw nothing. Everything seemed quiet and still except for the floor and walls creaking. Then he heard Hermione screaming from upstairs, "We're up here! We're up here! Sirius Black! Quick!"** She sounded terrified. What was he doing to them? He flew up the stairs, blasting the door open with his wand. He practically fell into the room.
Five pairs of shocked and frightened eyes stared back at him. Remus wasn't sure what he expected to see when he entered the room, but this definitely wasn't it. Ron collapsed onto the floor. Hermione looking even more scared than he felt. Harry staring up at him looking shocked and oddly disappointed. Just beneath Harry lay a pile of bloody, hairy rags that, sure enough, was his old friend. Sirius watched him, with a crazed, desperate look that he'd never seen on his face. On top of him sat a large cat, who looked more annoyed than frightened.
"Expelliarmus!" he shouted**. The kids looked relatively safe at the moment, so no one was going anywhere until he understood what was going on. He reached up to catch the three wands flying towards him and walked towards Sirius. A lump formed in Remus's throat as he stared down at the pathetic, unkempt man who had once been so confident and handsome. Sirius's eyes bore into Lupin's looking not defiant or angry, but pleading and terrified. Remus did not know what to think but instinct told him this was not the face of a killer.
Realizing suddenly that the fourth dot, Peter, was nowhere to be seen, he asked Sirius, his voice quaking, "Where is he?"** Sirius's face changed into the blank look he'd always worn when he was holding his emotions back. He pointed slowly towards Ron. Remus saw no one there other than the gangly red-haired boy, but a rat could be hidden anywhere. Come to think of it, hadn't he heard Ron talking about his pet rat?
"But then..."** he said softly, thinking aloud. "Why hasn't he shown himself before now?"** It had been twelve years. What would propel him to live as a rat for more than a decade? Why didn't he tell people that he was alive? That Sirius hadn't killed him? "Unless..."** he muttered. Peter might have been scared. He'd always been scared of everything, even his own shadow. Would he be scared of his best friends? But why? They would never betray Peter, just like Peter would never betray them. He held his breath. Or would he?
"Unless..."** he whispered again, hardly believing what he was saying but knowing he was right. "He was the one...unless you switched...without telling me?"** Sirius nodded. Remus immediately knew he was telling the truth. It all made sense.
All these years...all these years Sirius had been locked up while the rat had been free. An innocent man. Tortured, hunted, hated. Alone. But not anymore. Remus let his wand arm fall, walked toward Sirius, pulled him up, and threw his arms around him. Sirius was not alone anymore. Remus was not alone anymore.
**Quotes from Harry Potter and the Prisoner of Azkaban
A/N: I tried to stick as close to canon as possible. There is one discrepancy, however. In POA, Lupin forgot to go to Snape's office to take his final dose of potion. Snape hadn't brought it to his office prior to Lupin's arrival. I didn't realize this until I re-read that portion of POA after writing the story. I liked my version so much that I decided to keep it. I hope you can forgive a little mistake. Also, I created details about the Marauder's Map that aren't mentioned in the book - like zooming in. It's my way of making the Map easier to read and since no details are given in the book, it could possibly be correct.