Sirius had never thought about exactly what the dishevelled appearance of the Shrieking Shack meant.

He had always assumed that the shack was simply unkempt, that it had fallen into disrepair because it was home to no one but a werewolf once a month. But now, as he felt anticipation coursing through his body at the imminent moonrise, and as he ran his fingers cautiously along the jagged edges of a broken table, he realized exactly what it meant.

So, this is what Remus did before they became Animagi. It had been a sensitive subject at best, and they had never really talked about Remus’s transformations before. Sirius had known that things had gotten better after they began accompanying Remus after every full moon, but he had been unaware of exactly how much they had changed.

Deep, vicious furrows ran along the walls of the shack in sets of four. The claw marks covered most of the surface of the walls, the crisscrossing patterns mutilating the wood into unrecognizable shapes. Sirius imagined the same lattice of deep gashes being carved into Snape’s body.

Suddenly, sending Snape down the Willow didn’t seem quite so funny anymore.

Maybe Remus was right. Maybe he didn’t really take the werewolf situation quite seriously enough. But Sirius was absolutely certain of one thing, and that was that if Remus wanted him to understand completely the implications of being a werewolf, this was the best way to find out.

Through the small crack in the wooden boards covering the window, the last streaks of sunlight were stretching across the sky as the sun slid itself neatly into the horizon. His body could feel that the changes were about to begin. Sirius gritted his teeth in anticipation, raised his face skyward and awaited the coming moon.

Remus was already halfway to the door of Slughorn’s office before the professor had a chance to react.

“Where are you going?” asked Slughorn.

“Sirius isn’t coming,” Remus replied shortly. He was in no mood to explain the argument and Sirius’s motives, not when time was running short.

Inwardly, he cursed Sirius for being so absolutely stupid and inarguably insane. Who in their right mind would want to transform into a werewolf?

Of course, it was this kind of cute, touching insane stupidity that was one of Sirius’s most endearing qualities.

Dimly, Remus was aware that Slughorn had turned very very pale.

“Does Mr. Black know about your, erm, condition?” Slughorn whispered worriedly. “Because if he isn’t coming and hasn’t taken the proper precautions…”

“He knows. He’s gone down the willow,” said Remus, his hand on the doorknob, ready to leave.

“But where are you going?”

“To find him and force him to take the potion before he does something he seriously regrets.”

“The sun has already set, you’ll never reach him in time,” Slughorn protested.

“I have to try!” Remus yelled.

Slughorn looked temporarily taken aback at Remus’s outburst, but Remus was beyond minding his manners. Blind panic was beginning to overtake them. The transformation would be excruciatingly painful and every moment alone afterwards was pure agony.

“Think about this Mr. Lupin. If you can’t reach him in time, he’ll bite you the moment you get there. The smell of human blood will be irresistible to him,” Slughorn said, recovering from his initial shock.

Remus froze, halfway across the threshold.

“Think about your friend. Tomorrow morning, even without the antidote, the effects of the potion will wear off. If he bites you, he’ll be like you for the rest of his life. Do you really want to do that to him?”

What a stupid question, Remus thought savagely. Of course he would never want to condemn Sirius to such a fate. Ice cold dread flooded through his body. The wolf was something Sirius shouldn’t have to ever experience, much less alone.

Then suddenly something clicked in Remus’s mind. The smell of human blood will be irresistible to him… Human blood. But this was Sirius’s body. He was more than just a human, he was an Animagus. Remus had to find a way to transform, to make his way to Sirius and help him through the night.

He turned to Professor Slughorn and said in an eerily calm voice that wasn’t his own, “You’re right professor, it is too late. If you don’t mind, I’ll go back to my dormitory now.” He pointed at the two phials of antidote sitting on the desk. “May I take those with me in case I see him in the morning?”

“Of course,” Slughorn said, handing the phials to Remus. “But the potion should wear off shortly after sunrise. It won’t last any longer than about 15 hours”

The had taken their potions at five in the evening. Remus quickly calculated in his head. 15 hours would be eight the next morning. Slughorn was right; the potion would wear off around sunrise, or shortly after.

“Thank you, Professor,” Remus said pleasantly before striding out of Slughorn’s office, displaying a calm that was completely absent from what he was experiencing inside.

Once outside, he decided to give the Animagus transformation a try. He cursed inwardly for never asking Sirius, James or Peter exactly how it worked.

I want to be a gigantic black dog, he thought to himself.

Nothing happened.

Well, he hadn’t really expected that to work. He tried again, this time concentrating on a mental image of Padfoot, willing his body to change.

Still, nothing happened.

He gave a sigh of frustration. What he needed was to find James. He didn’t know how to bring off the animagus transformation, but James would be able to help him. Vaguely he recalled that James and Peter were in detention. He would have a job trying to find them. They could be anywhere.

He was halfway down the hallway when he thought of the map. The Marauder’s Map would tell him where James was, and then perhaps they could slip away to the shack together. He quickened his pace. If he hurried he could reach Sirius before long, and Sirius would only have to spend a few minutes as the wolf.

“Well, well, well,” said a silky, sarcastic voice from the darkened corridor ahead of him, “if it isn’t the jokester Black. Hope you’re not in a hurry Black, because I’ve got a bone to pick with you.”

Casually, twirling his wand deftly in his fingers, Severus Snape stepped out of the shadows in front of Remus, blocking the corridor and cutting Remus off from the one thing that could save Sirius a night of pain and torment.

The first thing to change was his hands, his beautiful, perfect hands.

Sirius felt his fingers shorten and draw together. He bit his lip to keep from crying out as the long sharp claws made their way across his lips.

And that was only the beginning.

His organs and bones were shifting inside him, rearranging themselves into the anatomy of the wolf, and he could feel every miniscule motion. He could feel the appearance of every new feature and the disappearance of every old one.

He could no longer keep himself from crying out. He let loose a terrified, pained shriek that sliced through the air and issued from the shack. But no one knew there was a person trapped inside the Shrieking Shack. “There goes those ghosts again,” they would murmur.

As the changes wracked his body, as he gasped and struggled to breathe, as he crumbled feebly to his knees and cried out over and over again, Sirius thought he was beginning the understand.

Being a werewolf meant excruciating, unbearable pain once a month. He had never been put under the Cruciatus Curse, but he imagined that it might feel something like this.

But Sirius had not even scratched the surface. As he writhed on the floor, struggling to cope with the physical changes that came with transforming, he didn’t know that the worst was yet to come: the mental changes, the loss of coherent thought and the absolute savage brutality that was the wolf.

“I don’t have time for this, Snape,” Remus said not unkindly. Snape was the victim. They, he and Sirius, had almost killed Snape after all, but at this moment he had no time to deal with their rival. Sirius was transforming, and he needed to find James.

“I’m afraid I can’t schedule things according to your convenience,” Snape sneered. “Not everyone considers you the embodiment of all things perfect, Black. I’ve told you already that I’ve got a bone to pick with you, and you’re not leaving until we’ve settled this.”

“Get out of the way, Snape,” Remus snarled, drawing Sirius wand, forgetting to be nicer to Snape. “I’ve got no time to deal with you right now.”

“Haven’t got time?” Snape asked in mock curiosity. “What could possibly be more important? Got girls to snog? Pranks to pull? Parents to talk to? Oh wait, I forgot, you don’t speak to your parents do you? What’s wrong, Black? They’re not impressed with the fact that you show murderous tendencies? I’d have thought they’d be pleased.”

“Don’t you talk about his parents!” Remus shouted back hotly.

“What the bloody hell do you mean ‘his’ parents, Black. Have you gone mad? Taken one too many bludgers to the head have you? Well I suppose you should be glad they can affect you through that tremendously thick skull of yours. Let’s hope they don’t ruin that face of yours.”

A wide, malicious grin spread across Snape’s face, indicating that this was exactly what he would like to see.

Remus didn’t have time for this. “Sirius being disfigured wouldn’t help you out, Snape. You’re not exactly next in line with the girls,” he retorted easily. “You should try washing your hair, I hear it’s really in this season. Now get the hell out of my way, Snape.”

Remus tried to push his way past Snape but the other boy moved to block him. The calm expression on Snape’s face slipped for just an instant, but he quickly recovered himself.

“Murderers don’t deserve anything or anyone, Black,” he spat. “You’ll be alone for the rest of your life if I can help it. If Dumbledore won’t punish you, I suppose someone has to.”

Gripping his wand tightly in his clenched fist, he pointed it straight at Remus. “You’ll pay for what you did to me, Black.”

Remus raised his own wand, but although his body may have been Sirius’s, his awareness was his own. He was a touch too slow. It was over in a few colorful flashes. Snape attacked viciously, fueled by anger and bitterness at nearly nearly being killed. After the first few exchanges, Remus didn’t have time to bring off a shield charm before Snape yelled “Incarcerous!”

Thick, twisting ropes shot from the end of Snape’s wand, wrapping themselves firmly to Remus’s wrists and ankles, binding his hands and feet. Remus overbalanced and fell awkwardly to the floor. The gravity of the situation hit him with the same intensity as the force with which he hit the floor. He wasn’t going to be able to bring Sirius help before long.

“Say good night, Black,” Snape sneered above him, and Remus could only watch helplessly as Snape raised his wand.

He smelled blood.

It was faint and far away, but the odor dominated his mind and commanded his actions. Hot, coursing human blood.

Frantically, Sirius pawed at the walls of the shack. Out. He needed out. He could taste the sensation of hot, coursing blood in his mouth, the soft feel of flesh shredding beneath his paws.

The wolf whimpered in frustration. It threw itself bodily against a boarded window to no effect.

Desperate and unable to find a way out, the wolf sprinted around the room. Blinded by the all-consuming need for blood, it collided painfully with the half broken table that stood in a corner of the room. The splintered edges of a severed table leg buried themselves into one of the wolf’s front let.

The sweet, acrid aroma of blood pierced the air. It was not the same as the human blood that his body so that he so longed for, but it awakened a deep instinct within him. To draw blood, to smell it, to cause pain, to hunt, to kill.

A vicious bite on a hind leg. The wolf howled in pain, but the tinge of deep red liquid on its teeth reminded it that the sacrifice of discomfort should be readily made. Again, it struck, this time clawing at its snout with its paw. And again, a chunk from its side.

A nip at its tail… a gash in its flank… a deep puncture in its paw…

As the night wore on, and the moon traveled its slow deliberate path across the starry sky, the lone wolf attacked itself again and again, howling in pain but unceasing in its efforts.

Remus had no idea what time it was or where he was when he awoke. All he knew was that it was totally dark all around him.

His head hurt quite a lot, and he was still bound tightly in the ropes that Snape had conjured. He groaned a little and tried to focus his eyes to survey his surroundings.

Either there wasn’t really a full moon tonight so the sky was a lot darker than he remembered, or he had been shut in some very small, very strange spelling room. He wiggled a little bit and tried to loosen the ropes that held his hands to no avail.

Suddenly it occurred to him that it could be any time and he could be any place. Someone might not find him for hours and he had no clue where he was. Sirius had definitely transformed by now and Remus had no way of knowing how long the other boy had spent as the wolf.

His wiggling became significantly more desperate. A bottle of some sort of liquid fell over and splattered all over the floor. Judging by the smell, it was some sort of cleaning agent. Great, that meant he was in a broom cupboard. He could be anywhere in Hogwarts, stuck in the dead of the night behind a door that no one would bother to open.

It was ironic that this was exactly the trait of broom cupboards that made them such appealing destinations for him and Sirius to sneak off to.

Desperately, Remus squirmed on the floor, trying to loosen the bonds around his hands and feet.

Another something clattered to the floor, but this time it wasn’t just a cleaning agent. His eyes adjusting slightly to the darkness of the cupboard, Remus shifted so that he was looking out at the object that had evidently just fallen out of the pocket of Sirius’s robes.

It was a small, ornate mirror that would fit comfortably into the palm of his hand, had he possessed the ability to free his hand at the moment. Remus stared at it, and through the worry for Sirius’s safety and the desperation of the situation, he remembered what the object was.

The two-way mirror! A spark of hope burst into Remus’s chest. He had been so intent on finding James that he had forgotten that Sirius always carried something on him for exactly that purpose. How could he have missed something so simple, so obvious? If he had only thought to use the mirror he could have saved Sirius, prevented him from Cursing himself for his own stupidity, he shifted himself so he was directly above it, and hissed into the mirror.

“James!”

Nothing happened.

“JAMES!” Remus yelled this time, not bothering to keep his voice down. If someone came to tell him off for being out of bed late, he would curse them into oblivion on sight, teacher or not. He was beginning to regret not taking this exact course of action with Snape.

There was a clattering sound at the other end of the mirror. Remus assumed it was a sleepy, groping hand searching on a nightstand for a pair of glasses and a wand.

“Lumos,” muttered a sleepy voice from the mirror. The glass of the two-way mirror glowed with wand light, allowing Remus to see a groggy looking James. “Wassamatter… s’late.”

“James, get the map.”

James hesitated, evidently confused that he was talking to a completely dark mirror.

“It’s Remus. Sirius has gone down the willow, James. We need to find him before long. He can’t spend the night alone.”

Immediately, the disoriented look disappeared from James’s sleep. It was replaced by a look of sharp focus, and Remus could hear the shifting of covers and the click of a latch to a trunk opening.

Suddenly, James’s face dropped, as though he had come to a realization that something terrible had happened.

“Remus,” James said slowly. “It’s too late.”

“What’s bloody too late? Just get the map, James, and come untie me.”

If James thought that Remus being tied up and trapped somewhere pitch black was abnormal, he did not show it. Instead he just shook his head slowly.

“It’s already dawn, Remus,” he said sadly, turning the mirror toward the window of their dormitory, where the first weak rays of sunlight were already filtering through the curtains.

“No,” Remus whispered, his heart filling with dread. Inwardly he cursed himself for not thinking of the mirror, cursed Snape for landing him in this situation, cursed Sirius for being thick-headed enough to want to transform. But mostly, he blamed himself for telling Sirius that he could not understand. Sirius had been so desperate for forgiveness, so eager to prove that he was capable of being serious, that he would willingly become a werewolf.

Deep down, Remus knew he should be touched, but mostly, he was just angry.

James had found the Marauder’s Map. Remus heard him mutter “I solemnly swear that I am up to no good” through the mirror and waited while James scoured the map for him.

“Blimey…” James said, sounding amazed.

“What is it?” Remus asked immediately, wondering what more could possibly go wrong.

“It’s nothing,” James assured him quickly. “It’s just the map. We did do some job on it, eh? It really does never lie. You’re still labeled ‘Remus Lupin’, stuck in a broom cupboard on the fourth floor. I’ll be there in just a moment.”

The mirror went dark, and Remus was quite alone in the cupboard. He lay there, trying not to panic and trying to let his mind wander to Sirius. An entire night as the wolf… how horrified would Sirius be? Would he even want to speak to Remus anymore?

Fighting the cold dread building in his heart, Remus waited impatiently for James to arrive. He tried to block out the memories of what it felt like to be the wolf, tried not to imagine what Sirius might look like, what he might think now.

Remus thought he knew, for the first time, what it must feel to be Sirius. To be affected by Snape’s words. Although Snape had thought he had been insulting Sirius, the words about spending the rest of his life alone had struck particularly close to home with Remus. Hadn’t that always been his worry? That because of the wolf, no one would ever love him, would ever understand him.

Why oh why couldn’t he have forgiven Sirius earlier? Remus had been so sure that he was going to be alone, and then Sirius had come along. He had forgotten exactly what Sirius had done for him, and now it might be too late. The wolf changed people. Who knew what Sirius would be like now? Remus thought it was likely that Sirius would never want anything to do with him again.

Alone… he would be alone, without Sirius for the rest of his life.

God he hated Snape for pointing that out.

The seconds ticked by every so slowly, and finally, at long last, the door to the broom cupboard swung open.

James, silhouetted against the faint flickering light of the torches in the hallway and the creeping rays of weak sunlight stood in the threshold. When he caught sight of Remus, he stopped dead.

“What is it?” Remus asked.

Remus thought he imagined a flicker of a smirk cross James’s face, but it was replaced almost immediately by a look of concern and worry. James bent over and severed the ropes with his wand. Pulling Remus to his feet, James asked, “What happened to you?”

“Had a run-in with Snape,” said Remus, still seething over the encounter. He brushed the dust off of his robes, and started to say that they should hurry when he noticed that James was still staring at him peculiarly.

“What?” Remus asked, unnerved.

“Snape must’ve been really mad at you,” James said simply.

“Look the moon’s already set, so Sirius should be back to normal by now. Do you… do you mind if I go find him by myself James?”

James hesitated for the slightest of moments, but then a look of understanding crossed his face and he gave Remus a half-smile. “Of course.”

Remus dashed down the corridor, bursting out the oak front doors and sprinting the distance of the lawn.

The soft orange light from the crack in the window seemed unbearably bright to him. Shaking and sore, covered with scratches and bruises, Sirius gingerly crawled his way toward his wand.

He hadn’t thought about the fact that changing into a werewolf would shred his clothes. That was his problem, wasn’t it? That he never planned ahead.

With shaking fingers, he raised the wand and tried to conjure a blanket. Clothes were too complex for him in his current state. On the fifth try, he managed to produce a raggedy old blanket. He shivered and pulled it around himself.

Exhausted, Sirius sank against the bare wooden wall of the Shack and huddled himself in a corner. Soon, when he regained his energy, he’d make an attempt to leave.

Shuddering, he closed his eyes and tried to shut out the memories of the previous night. A vivid image of his blood-stained mouth and hungry howl appeared unbidden in his mind. He shuddered violently and drew the blanket even closer around him.

Every month, he thought to himself, Remus did this every month. He could not imagine, could not know the pain of doing this every month, nor could he begin to think about how he would feel if he attacked Snape like this. It was monstrous. He was monstrous. This thing that grew inside his body was not his own, and yet it controlled him utterly and completely.

He clenched his fists tightly into the blanket. Still shaking slightly he squeezed his eyes shut tightly and tried to will the evil thing out of the body, to make it leave him. He was not evil, he was good, what was this thing doing to him.

Half lucid, shivering violently, huddled against the corner of the wall, Sirius sat, lost in his own thoughts. The wolf was alone. The wolf was isolation. He, Sirius, had been alone with evil. Who would ever want to go near him again?

Suddenly, with a bang, the door from the passage burst open.

“Sirius?”