Disclaimer: I don't own Harry Potter.

AN: This story has nothing to do with 'Not What You Think' or any of my other stories. I don't know much about the shrieking shack, but I think a bed is mentioned in the third book – this isn't there in this story – it was put in later. I have never written a werewolf scene before, so please bear with me. This chapter is mostly thoughts and feelings, but next chapter will have more speech in it. If you are reading this for the second time, this is not an update, it's a spelling correction.

Summary: The marauders' friendship is put to the test when Moony attacks a student - a student that happens to be his best friend's brother. Will Sirius ever forgive Remus?

Chapter One

Sirius hadn't really had a good day. His younger brother had just been sorted into Slytherin; a house that contained nothing but slimy gits such as Severus Snape and Lucius Malfoy. He hadn't been happy that Regulus had chosen to please his Mother rather than be sorted into Gryffindor, and worse still had ending up arguing with Regulus about it. The first year had run off upset, leaving Sirius feeling incredibly guilty.

On top of that, there was a full moon that night, and one of his best friends was a werewolf. After finding out the previous year, Sirius, James and Peter had been trying to find a way to help him. James had insisted that it was possible for them all to become animagi – this, if it worked, would mean that they could spend the full moons together without anyone getting hurt. However after almost a year of research, nothing they had found so far had done anything helpful towards achieving their goal.

Sirius glanced one more time at the night sky outside the commonroom window, before packing up his things and retreating upstairs towards the dormitory where his other two friends were waiting.

That night, all three of them were woken by a loud howl and an ear-piercing scream.

…..

While Sirius had been getting ready for bed, on the other side of the castle Remus Lupin was preparing for yet another night in the shrieking shack. As Madame Pomfrey led him towards the secret passageway, he thought about his friends back at the castle.

He was lucky really to have actually been allowed to stay at the school – Dumbledore was the only headmaster in Hogwarts' long history to have accepted someone like him into the academy. However, not only had he been allowed an education, he had also been accepted into a close friendship with his three roommates. What he didn't understand, however, was how the three of them didn't seem to care about his condition. Of course, he was grateful that they hadn't screamed and demanded to move dormitories as soon as they'd found out, but he had found it very hard to understand why the three of them had not thought of him as a monster.

It bothered him slightly that Sirius, James and Peter had been talking secretly amongst themselves. When he had asked about it, they had said it wasn't anything bad, but that they couldn't tell him about it. At the time he had assumed it was a prank, but he really wasn't sure.

Madame Pomfrey tapped the knot on the whomping willow, causing its branches to still. The passage underneath was dark and narrow. If he hadn't been so worried about his transformation, he would probably been frightened at the prospect of entering it. However, since worse things could happen if he didn't go in, he followed the nurse without complaint. When they reached the shack, Madame Pomfrey made sure he was settled and then Remus was left on his own.

Oh, how he hated that shack! It had been purpose-built for him but it lacked any form of comfort whatsoever. There was no heating, no lights, and nowhere at all that was comfortable to sit. The walls were covered in deep scratches where he had tried to get out on multiple occasions the previous year. Stargazing was not an option, as the windows had all been bordered up. Instead, Remus sat in a corner with his knees pulled up to his chest, and waited for the full moon.

When it came it wasn't pleasant. At about half nine in the evening, a gap in the clouds appeared and the moon lit up the whole of Hogsmeade. Of course, Remus couldn't see this, but he knew it must have happened. He felt a searing pain in his chest and limbs as all the bones in his body tore apart, rearranged themselves, and lengthened. The anatomy of a wolf being quite different from that of a human meant that all his internal organs also had to change their size and relative proportions.

Fully transformed, Remus was no longer Remus. All trace of rational thought was gone, and he was now left in a small, bare room, which was by no means the natural habitat of a werewolf. The wolf hated it. It wanted to be in the forest! So without further ado, it began to scratch the walls, looking for an escape.

Unfortunately, the werewolf found a weak point where the wood blocking the windows ended. Using all the strength it could muster, the werewolf managed to break the wood. This resulted in a large hole, through which the werewolf slipped through. It landed on the grass outside the shrieking shack and headed towards the forbidden forest.

...

Earlier that evening, Sirius and Regulus Black had been arguing. Upset at his older brothers accusations (namely that he was a coward and would never do anything against his mother's wishes), the younger of the two had run off crying. Now, two hours later, Regulus was still a little upset and was curled, fully-dressed on his bed in the foetal position.

"Are you going to get changed, Regulus?" asked one of his dorm mates. Regulus ignored them. "What on earth's got into you?"

"Sirius," muttered Regulus.

"If I were you, I wouldn't care what that blood-traitor thinks," replied the other boy.

"Sirius isn't a blood traitor!" shouted Regulus indignantly. He stomped out of the dormitory and back into the commonroom, where he sat as far away from human contact as it was possible to get.

The problem was that Regulus had actually wanted to be sorted into Gryffindor, like his brother. However, his mother had said that if he was sorted into any house other than Slytherin, she would teach him a lesson and then disown the both of them. Regulus hated the idea of getting Sirius into trouble – Sirius received enough punishment from mother without his intervention too! He also couldn't bear the thought of being disowned. Where would he go? He didn't have any friends outside his mother's social circles, and who would want to be burdened with a blood traitor like him or Sirius anyway?

So when the sorting hat had been arguing with itself over whether to put him in Hufflepuff or Gryffindor (loyalty or nobility, it had argued), Regulus had insisted that it put him in Slytherin. And when he had seen the disappointed look on Sirius's face, he had mouthed 'talk to you later', and that was what he had done. However, when Regulus went to explain to his brother what he had done, Sirius hadn't let him do it. Instead he had called Regulus a coward.

After thinking it through for some time, Regulus decided the best thing to do was to prove to his brother that he wasn't a coward; that he could disobey the rules. That was how Regulus deliberately set out on his mission to get detention…

He set out towards the forbidden forest. That would surely get him detention: the name of it even had the word 'forbidden' in it! He had also heard that Sirius had been there lots of times last year too.

It wasn't until he was about a hundred yards into the forest that he began to have doubts. The forest was surely forbidden for a reason. What if Bellatrix's stories of Acromantula and Giants were actually true? He jumped as he heard a hoot, but it was only an owl, so he went onwards.

Suddenly he heard a loud howl, unlike anything he had ever heard before. He stopped dead in his tracks and listened. Then he heard it again. This time it was closer. He turned around and there, just a few meters away was the unmistakeable form of a werewolf!

He stood stock still, his feet glued to the floor. When the werewolf's back was turned, he made a break for the edge of the forest. But he wasn't quiet enough. The werewolf heard him, and chased after him.

He ran and ran, but the werewolf was fast. He could almost feel its breathe on the back of his neck! He would never make it to the castle, so instead changed direction towards the small hut on the edge of the forest. He banged desperately on the door, but just as it was about to open, he felt its teeth bite down hard onto his shoulder, and felt its claws on his back.

He screamed, just as the door opened to reveal the figure of an enormous giant. Whether it was from fear, blood-loss or shock, no one will ever know, but right then – for Regulus at least – everything went black.

…..

AN: I hope you enjoyed reading this. And to those of you who have read my other fiction, this is completely separate. I do write things that aren't to do with Regulus – I have a story on Olympian Gods, and one shots coming up about Mad-eye Moody and Arthur Weasley. In the meantime, please could you review this story:

What do you think will happen to Regulus? Will he survive?

Will Sirius still be friends with Remus after what has happened?

If not, who would James side with?

How will Remus react when he wakes up the next morning?

What do you think of the general plot and characterization so far?

Thanks for reading and please review….