(Of course, all credit for characters, setting, everything goes to the forever unsurpassable JK Rowling.)
With dusk beginning and the last rays of an orange sun streaking across a pink sky, three boys watched from the shadows of the aqua-duct as two figures hurried down towards the games keeper's hut. The smaller of the two was wearing a cloak, but as he stumbled over a stone his hood slipped back and the boys could recognise, even from that distance, the pale and clammy pallor of Remus Lupin's skin. This was slightly strange because their room-mate was meant to have gone home to visit his ill mother. Again.
The trio crept quickly down the steps and past Hagrid's hut, not wanting to lose sight of Remus. The pair stopped just out of reach of the Whomping Willow, a humongous and violent tree, it's club-like branches swinging and creaking in an effort to reach them. Madam Pomfrey produced her wand and sent a stone flying through the branches. It hit off a knot at the base of the trunk and immediately the tree went still. They continued on past the frozen branches and, suddenly, seemed to fall into the tree. Once they were out of sight Sirius Black counted to ten and threw off the invisibility cloak they had been hiding under. He went straight to the tree, which had remained still. The three Marauders rushed to the base and, right beside the knot that the rock had hit, there was a gap in the thick roots. Peter, it was decided, should go down first. He deliberated how to do it for second, stalling for time before Sirius pushed him. He shot down into the darkness. After a short shriek and a muffled, earthy thump he called up,
"It's some sort of slide!"
Next went James, then Sirius, just as the last glimpse of sun set over the Forbidden Forest. With a whispered "Lumos" James illuminated the tunnel, revealing a rough passageway leading off into the distance with roots criss-crossing along the roof and sides, preventing the tunnel from caving in.
They had been walking for a while with their light tips glowing and the occasional "I really don't think we should be here." from Peter when they heard footsteps around the next corner. Immediately extinguishing their wands, James threw his Father's invisibility cloak over all of them and they pressed their backs tight to the tunnel wall. They barely dared to breathe as Madam Pomfrey passed by them, almost brushing against them in the cramped space. She continued on her way and the boys waited until the light from her wand faded out of sight before taking off the cloak.
At the end of the tunnel was a ladder leading up to a heavy iron trapdoor. Shushing Sirius who had taken to singing a drinking song to drown out Peter's worries he lifted the trap door slowly and peeked into the room above.
It was dark, with no lamps and the only light coming from the full moon. The house was old and decrepit. Looking past this James noted long gouges in the wall that looked an awful lot like scratch marks and thick bars on the window. As well as that James heard laboured breathing and a pained yelp. Straining his eyes he saw a shadowy figure lope into his view. It appeared to be in pain, scratching at itself and drawing blood with it's long, sharp claws. As it reached the window and the light of the full moon fell upon it's face, the creature tipped back it's head, opened a mouth filled with pointed canines, and howled. It was, typically, at this opportune moment, that Sirius chose to yank James' leg from below and call;
"What the hell was that?"
Immediately the werewolf, for it could be nothing else, whipped it's head around. It's dark eyes meeting James' and it began to lope across the room, quickly covering distance. James who had been frozen in fear for a moment managed to shut the trapdoor a split second before he heard scrabbling and growls on the other side of it.
"GIVE ME A HAND HERE!" He yelled at the other two and between the three of them they managed to draw the bolt across.
He then took off sprinting down the tunnel again, back to the school, with the other two closely behind him and they burst out into the open. Sirius would have been knocked out by a clubbed branch of the Whomping Willow if Peter hadn't had the presence of mind to step on the knot a split second before impact. The three of them rushed off and fell down onto the grass on their backs. Panting, James recounted everything he had seen.
"You know what this means, right?" Peter said, after a pause.
"Our best mate's a werewolf." James replied.
...
Staring up at the star speckled sky and the bright moon Sirius grinned, "Amazing."
"We know he's here Madam Pomfrey!" Sirius argued loudly the next day, as she stood in the doorway of the hospital wing, blocking their entrance.
"I don't know what you're talking about!" she replied sternly. "Mr Lupin has gone home, and I like to think I would know if he was in my care."
With a lowered voice James looked up at her with as serious an expression as he could muster and said "No Madam Pomfrey, we know he's here."
With slightly raised eyebrows she still refused them access.
"You boys should get to breakfast or you'll miss it. Hurry along now." And watched until they were around the corner and out of sight.
"You know what we've got to do?" James asked.
"Break in." stated Sirius as if it was the most obvious thing in the world.
"Of course." Peter sighed, defeatedly.
...
"This is a really stupid idea." Peter pointed out.
"Well, you refused to dress up as Alison Fitzgibbons and sneak in in disguise so this is Plan B." Sirius retorted.
The three of them were on broomsticks, hovering thirty feet in the air, outside a hospital wing window. James, pressed against the wall, had been looking in at the wing and motioned them over.
"She's gone into her office, c'mon, quickly."
Opening the lock he pushed the window up and gracefully swung into the room. Sirius followed with ease and Peter got in only by the assistance of the other two. Once they were all settled, crouched on the floor they paused for a second to make sure Madam Pomfrey hadn't heard them. When they heard no movement from her office, Sirius rolled across the floor to the bed directly across the room. James one-upped him with a backwards roll and Peter went for a simple and reliable crawl across. Seeing Remus in none of the open beds, they hurried across to a bed surrounded by a curtain in the far corner.
Slipping inside they saw that it was, indeed, Remus lying curled up in a ball on the bed, whimpering in his sleep.
"Should we wake him?" Sirius asked.
"Nah," Peter replied, "look at him he looks really sick and also… is it safe?"
James cuffed him up the back of his head, "Shut up you idiot, it's Remus."
"But, yeah" he conceded, "We should just let him sleep."
James pulled a bar of chocolate from his pocket and laid it on the bedside table. They sat, leaning against the wall and whispered to each other while for their friend to wake. He was stirred by their chatter though, and as he rolled over, the three jumped up.
"Aggh!" Remus yelled in surprise, shocked to find them leaning over his hospital bed.
"Shhh!" Sirius admonished. "You'll get us caught-"
But they could already hear Madam Pomfrey leaving her office.
"Dammit Lupin!" Said James. "Better make this quick, we just wanted to say that we know. We followed you. We brought you some chocolate and we hope you feel better soon!"
With that he yanked back the curtain, Sirius gave a wave to a stunned Madam Pomfrey who had almost reached the bed, and all three of them sprinted across the room to the open window, leapt out onto their waiting broomsticks and flew off laughing with adrenalin, Madam Pomfrey yelling from the window at them.
Needless to say they all got detention, but would always maintain that it had been completely worth it.
...
Three of the Marauders were hanging about their room, Sirius finger-picking a tune out on his guitar, Peter and James working on homework together; when Remus returned from the hospital wing. Mercifully their fifth room mate, Brendan Hurst, wasn't present.
The three Marauders sat up and turned to him as he opened the door, and Remus looked like he was considering leaving for a minute before he walked defeatedly over to his bed.
"I suppose you want me to leave then." said Remus. Frowning, James opened his mouth to contradict him but Remus continued, "I mean, I can't blame you. I wouldn't want to be in the same class as me, let alone sleeping in the same room if I were you." He slid off the bed, and reached for his trunk.
"What the hell are you doing?" asked Peter.
"Packing." replied Remus simply.
Jumping across the room Sirius slammed down his trunk lid, Remus barely moving his fingers out of the way in time. "Well quit it."
Remus finally looked at his best friends, all of them wearing matching expressions of confusion.
"But, you said, you knew and - "
At this Sirius at least had the grace to look embarrassed. "Yeah, we sort of followed you last night…" he said, rubbing the back of his neck.
"It's just," James said, "Well, you can't exactly be going home every single month? And you always seem to go home around the time as you start looking sick. So we just kept an eye on you for the past week is all."
"And then yesterday afternoon," Peter picked up the story, "When you said you'd got another note from your Mum, I just followed you from the portrait hole to the Hospital Wing."
"From there it was just a simple matter of waiting outside the hospital wing under the invisibility cloak until you and Madam Pomfrey left, well we assumed it was you under the cloak and followed you."
James proceeded to tell him the rest of the story but stopped midsentence at the pained expression on Remus' face when he got to the bit about seeing him in the house.
"You idiots!" Remus whispered, all the remaining blood draining from his already pale face. "I could have killed you! I almost did!" He looked like he was about to be sick. "How can you stand being in the same room as me? I'm a monster."
"What?" said Sirius, "It's bloody brilliant!"
This, evidently, had not been what Remus had been expecting to hear. "You aren't going to tell anyone?" he asked.
"Course not." said Peter.
"We would never stop being best friends just because you're a-" Remus winced in anticipation of the word. "-just because you have a… furry little problem." James smoothly corrected. "You're a Marauder, and you're stuck with us for life."
"Seriously?" he flopped back onto the bed and threw his arm over his eyes, "Oh thank Merlin."