'For suddenly a grievous sickness took him,
That makes him gasp and stare and catch the air…
…And whispers to his pillow, as to him,
The secrets of his overcharged soul…'

- from Henry VI, Part One

His Overcharged Soul

It didn't take a NEWT in Divination to predict that Remus was about to disappear. All the signs were there. He was pale and peaky, quieter even than usual and more skittish. On Wednesday he had begged off going down to the courtyard, and had instead gone to bed – before supper! From the deadened expression in his eyes on Thursday, the only thing that had kept him up that night was the necessity of attending their Astronomy lesson. And there was the incident in Herbology to think about. Remus was never the picture of health, but Sirius hadn't ever seen him bent over a puddle of sick before. It had been disturbing, even rather frightening, and Remus's refusal to go to the hospital wing had made Sirius uneasy.

Since the beginning of term he had been keeping both eyes open for any sign of the culprit who was – who must be – hurting Remus. Although he hated to admit it, the Slytherins seemed to be innocent. The only one Sirius had even seen talking to Remus since school began was Professor Slughorn, and although Sirius hadn't officially ruled out a teacher as the source of his friend's mysterious disappearances the portly Potions Master did not rank on his list of suspects. Slughorn lacked not only the guile for such wicked goings-on, but also the intelligence to come up with a decent plan and the physical dexterity to successfully land a blow.

It seemed highly improbable that any of the other teachers were involved. Alfstin really had been a likely candidate, with his bullying nature and his failing faculties, but even so Sirius could not quite believe it. Alfstin was an angry old git, but whoever was responsible for Remus's disappearances and his mysterious injuries and his obvious worry and illness before and after vanishing had to be worse than a git. Whoever it was, he or she was evil, responsible for the sort of horrific cruelty Sirius had never imagined someone could inflict on another person's child. The thought of anybody preying on Remus – quiet, trusting, studious Remus who had never hurt anyone – made his blood boil with all the vitriol ancestral to the Noble and Most Ancient House of Black.

So when he realized that Remus's disappearance was imminent, he took steps to follow him. James had gladly contributed his Invisibility Cloak for the enterprise, though Pettigrew, predictably, had voiced some concerns.

'Are you sure you want to do this?' he had said that morning while Remus was in the shower. 'What if somebody is hurting him? What if whoever it is tries to hurt you, too? Do you really want to get mixed up in all this?'

Sirius would have yelled at him for being a cowardly, insensitive prat, but then Remus would have heard. Sometimes Sirius felt uneasy about all the secrecy. It didn't seem fair to talk about Remus behind his back, when he knew Remus would never talk about him that way. But there really didn't seem to be any other way to work through the mystery. It was obvious, even to James, that the incessant questions upset Remus dreadfully, and none of them wanted to add to his troubles – whatever they might be. No, it was better to talk amongst themselves when he wasn't around to hear, or while he was sleeping. It was kinder.

At least, that was what Sirius told himself.

Remus had been distracted in Defence Against the Dark Arts. Meyrigg had definitely noticed, but she hadn't said anything. So Sirius wasn't the least bit surprised when, halfway through the pilgrimage to Binns's classroom, James nudged him in the ribs.

'He's gone!' he whispered.

'Where did he go?' Sirius hissed, spinning around so quickly that he startled Vivian Viridian. She brushed past him, but he hardly noticed. There was no sign of Remus. 'Sod it! He was just here!'

'He was lagging behind,' Peter said quietly; 'only you didn't notice. You two don't usually notice when one of us is slower.'

The remark might have been meant as a criticism, which was a privilege Pettigrew was not ordinarily allowed, but Sirius chose to ignore it. He had other, more pressing concerns. 'I've got to go,' he said, slinging his satchel around to the front and digging inside it for the Cloak.

'Don't do anything stupid,' James said, moving smoothly to obscure Sirius from prying eyes as the latter slipped behind a nearby suit of armour and shook out the shimmering cloth. 'Just see where he goes, and then report back.'

'And be careful,' Peter added worriedly.

Fortunately Sirius was already concealed within the diaphanous folds of the Invisibility Cloak, and was therefore exculpated from the obligation to answer them. He nudged James as he skirted around him and then started back down the corridor at a measured trot. He tried to think where Remus might go, but that was a pointless exercise. If they knew where Remus went, after all, there would be no need to follow him. Still, Sirius wondered when exactly his friend had slipped off and whether he had any chance of catching up to him.

As it turned out, he needn't have worried. He came upon Remus in the next corridor, toiling along with stooped shoulders and a bowed head as if the very effort of walking was too exhausting to endure for long. As he turned a corner to start up the stairs Sirius caught a glimpse of his face: blanched and drawn, his lips pressed tightly together as if he was in pain. His ordinarily soft and pleasant eyes were bleary with weariness and a quiet despair that made Sirius's innards clench with understanding. Whatever awaited Remus, he dreaded it with every fibre of his being and he knew he was powerless to stop it. All that he could do was submit himself and endure.

The anger resurfaced, and Sirius found his pace quickening so that he was practically on Remus's heels by the time the younger boy reached the portrait-hole. He gave the password to the Fat Lady in a small, weary voice that wavered as if his strength was failing him, and Sirius slipped through after him.

It was a painful thing even to watch Remus struggle up the stairs to the dormitory. He canted to the right, his left shoulder pressed nearly to his ear with the effort of supporting his book bag. Both hands clutched the bannister and he moved one before the other with each step as if his arms, and not his legs, bore responsibility for carrying him to the next stair. Sirius lingered several paces behind, noticing uneasily that Remus put both feet on a step before moving to the next. THUMP-bump. THUMP-bump. THUMP-bump.

The sound roused a vague childhood memory: darkness and aching ribs, a pinched belly and the painful, searing sensation of an overtaxed bladder as he huddled in a dusty corner waiting for his reprieve. That same sound, THUMP-bump, THUMP-bump, THUMP-bump, on the stairs below, and the moment of hoping desperately that the footfalls belonged to his mother, come to let him out and take him downstairs where he could use the toilet and eat a hot breakfast and stretch out on his big, soft, warm bed. Then the shuddering despair when he realized that it was only Regulus, with his fat little three-year-old legs, coming to crouch down and push a piece of soggy toast under the door and ask in his lisping baby voice when Sirius would be able to come downstairs and play with him – as if Sirius had any say in the matter at all.

Sirius was so lost in his thoughts that he very nearly missed his chance to slip into the dormitory with Remus. The door struck his shoulder and he clutched frantically at the handle to prevent it from flying open again. Breathlessly he slipped through the narrow gap and scuttled away from the door as Remus, sighing softly to himself, doubled back to close it properly. He looked warily around the room, as if to be sure it was empty, and Sirius held his breath. It was a calculated risk, after all: to follow Remus, who knew about the existence of the Invisibility Cloak. He wasn't sure how he'd explain himself if he were caught. Or rather, how he'd explain himself without hurting Remus's feelings.

The other boy had opened his cupboard, and he was rummaging inside for something. His faded cotton nightshirt landed on the edge of the bed and Sirius frowned. Had Remus decided to cut History of Magic so that he could have a nap? Maybe he did just have a touch of the Collywobbles after all. It would certainly explain why he'd thrown up the other day.

But now Remus was pulling out another pair of robes – a shabby old blue pair with a ragged hem and two buttons missing. He took out his cloak, too. Then he began to undress, shimmying out of his school robes. He started on his undergarments as well, but by that time Sirius wasn't really watching his actions. He was staring at his skin.

Scars.

Dozens of scars.

Dozens upon dozens.

Scars on his arms and his legs, pale crescents and angry red blotches and purplish ridges. Scars on his shoulders. Scars on his ribs. A horrible, twisting mass of knotted tissue just over the crest of his right hip, as if someone had dug out a handful of flesh and then tried to draw the ragged edges together too quickly. There were some as fine as the rakings of a fingernail, and some so large that they seemed to have been made by dragon's teeth.

In fact, Sirius realized in horror, most of the scars did look as if they'd been made with teeth – or at least some sort of curved, serrated instrument of torture. He could not imagine what might have inflicted such horrific damage on the small, bony body of his friend. He could not explain why the wounds had been allowed to remain like this. He knew that Remus's parents didn't have much money for things like dittany, but surely a competent Healer could have mended the hurts more neatly than that. Remus was hugging his arms to his chest now, his collarbones quivering a little with the cold. Sirius thought of kind, clever Mrs Lupin, and he could not understand how she could have failed to protect her son from whatever monster had done this to him.

Unless, of course, she did not know.

A tiny, guttural sound welled up in his throat. It was not a roar, though he had never felt such anger. It was not a wail, though he had never imagined such horror. It was not a sob, though he had never longed so desperately for tears. It was just a sort of a soft, burbling noise that bubbled over his teeth and out between his lips before he realized he was making it.

Sirius clenched his jaw, pressing a hand over his mouth and nose to keep any other sound from escaping. Remus stiffened a little: surely he had heard the noise. But instead of calling out to demand the identity of his tracker, he hastily pulled on the old blue robes without troubling with fresh pants. He tugged at one fraying sleeve, his mouth twitching ruefully when it didn't meet his wrist.

Then he dumped out the contents of his satchel, filling it with the nightshirt and some underpants and socks and a pair of his school robes. He looked around briefly before grabbing his Defence Against the Dark Arts textbook off of the bed. The rest of his belongings he stowed away with such swift, mechanical efficiency that Sirius wondered whether Remus even knew he was doing it. Quill and ink and parchment went into the cupboard. He tucked his wand into the front pouch of his satchel. The underclothes and robes he had shucked were deposited in the laundry basket in the corner. Then he grabbed his bag and clutched his cloak around him and hurried from the dormitory.

Again Sirius was slow, and again the door struck him – this time in the rump. Remus's frustrated moan made his stomach wrench with remorse even as he danced back out of the other boy's path. Remus struggled down the stairs. This time he had only one hand on the banister, though it trembled. In the common room Sirius was ready. He pressed as near to his friend as he dared, slipping out of the portrait-hole at the same moment Remus did. The edge of the cloak brushed Remus's arm and Remus shivered, stumbling forward and looking wildly around. Sirius backed against the wall, holding his breath. But the Fat Lady swung back into place and Remus shook his head, raising his hand and pressing the back of his wrist to his brow. It was a peculiar gesture, but it lasted for only a moment or two. Remus's arm fell back to his side and he started down the empty corridor.

Aware of how easily footsteps echoed on the flagstones, Sirius modulated his steps so that they fell in time with Remus's. The other boy didn't seem to hear him, and he wound his way down one hallway and up another, and then to a long flight of steps. Sirius had quite lost track of where they were when Remus led the way around a corner and they came out just a few yards from the door to the hospital wing.

Sirius halted. The hospital wing? Remus had seemed so reluctant to visit the matron two days ago, and now here he was at her door. A deep frown furrowed his features, and despite the niggling voice in the back of his head that insisted, with Andromeda's intonation, that when he scowled he was the spitting image of Arcturus he yielded to it. This did not add up. It was a puzzle, another anomaly in a long series of anomalies that added up to nothing at all but somehow always left Remus exhausted and sickly and hurting.

For a single, horrible moment Sirius wondered if the matron was the one who had been harming Remus. Sure, she seemed like a decent sort of a witch: a bit strict, maybe, but dignified and sensible and fair. Of course, that was probably just what people like the MacMillans thought about his mother. The mask of dignity could hide all manner of cruelty.

But then Remus opened the door, and Sirius heard Pomfrey's voice calling out to him, cheerful and fond. 'You're early, love,' she said. 'Welcome back!'

Sirius tried to sprint forward before the door could swing closed, but he did not make it. Remus hauled on the handle and there was a groaning of the hinges as he leaned against it. Undaunted, Sirius bent to the keyhole, ears pricking.

'I've missed you dreadfully over the summer,' Madam Pomfrey was saying. She sounded so very kind and so genuinely happy to see him that Sirius felt ashamed for thinking ill of her, even for a minute. He was glad that she sounded that way. Remus didn't always seem to think he was likeable: he needed to know that there were people who were happy to see him. 'How did everything go at home?'

It seemed a funny sort of question to ask, and Remus didn't seem to know how to answer it. When he spoke at last, his voice was soft but earnest – and above all free from fear. 'Everything went well, Madam, truly,' he said. 'I hurt my leg in July, but otherwise it was all very usual.'

Sirius's eyes narrowed. That wasn't right, either. Remus had hurt his leg in August, not July, when he'd fallen off of the climbing bars at the little playground near his home. It wasn't like Remus to be imprecise about that kind of detail: he was always the one correcting everyone else. So either he was so ill and addled that he was growing forgetful, or he'd hurt his leg in July as well. It had never sat right with Sirius, who had experience far more dramatic falls from broomsticks and garden walls and down stairs without noteworthy injuries, that Remus had broken his leg tumbling from a children's apparatus…

Pomfrey was talking again, saying how she'd hoped Remus might have stopped in to visit her earlier and how she'd been wondering after him. Remus, his voice soft with wonder, apologized. 'I didn't think…' he said, his voice trailing off in that way it so often did.

The matron said something else, but they were obviously moving away from the door, because Sirius couldn't make out the words. Frustrated, he dug his fingertips into the palm of his hand. There was nothing he could do for the moment. The hospital wing door was closed, and if it opened of its own accord Pomfrey would ask questions and Remus would think of the Invisibility Cloak and the whole escapade would be uncovered before he'd done anything more than uncover a hundred fresh questions without answers.

~discidium~

There was no question, at least, of skiving off from Transfiguration. Professor McGonagall would have hunted him down and slapped him with detention. In any case Sirius was ravenous and neither Remus nor Pomfrey looked to be making any move to leave the hospital wing. So after a while he shucked the Invisibility Cloak and made his way to the Great Hall to meet James and Peter for lunch.

'What's it all mean?' James asked after they had finished their hurried meal and gone out to sit at the base of the great marble staircase in the Entrance Hall.

'I don't know,' Sirius admitted unhappily. He had explained about the packing and the journey to the hospital wing, but he hadn't mentioned the scars. It didn't seem right. Remus took such care that they shouldn't see them, changing in his bed every single night. It didn't seem fair to tell the others. Remus kept his secrets, after all: he hadn't told the others about the times he'd seen Sirius blubbing. 'The matron made it sound like the whole thing's a pretty regular occurrence. She asked if Remus got on all right at home, too.'

'But we've ruled that out,' James said. 'His parents aren't hurting him. They're good people, Sirius. You've met them: you know that.'

'They're not hurting him,' muttered Sirius. 'But maybe they're not seeing something they should be seeing.'

'Like what?' asked Pettigrew.

'How should I know?' Sirius exclaimed. 'But somebody's got him scared and hurt, and they ought to protect him. That's what parents are supposed to do, isn't it? Isn't it?'

It was what he had always imagined parents were supposed to do. When you heard stories about a mother diving into a river to rescue her child even though she didn't know how to swim, or about that old wizard in Norway who had gone up against Grindelwald's advancing army all by himself to give his daughters time to Disapparate – that was what parents were supposed to be like. Even though he wasn't fool enough to believe that all parents met that standard, he couldn't quite believe that Mrs Lupin, of all people, would fail her son so spectacularly. That was worse, somehow, than knowing his own mother wouldn't cross the street to Levitate him out of the way of an oncoming bus. He didn't want to believe it. Remus had a good mother. He deserved a good mother. It couldn't be true.

'I suppose we know where he goes, anyway,' James said quietly. Only then did Sirius realize that he had fallen into a lengthy silence that was only now being broken. 'Maybe we should just let it alone. Pomfrey will take care of him.'

'But she doesn't,' Sirius said. 'What about those bruises? And what if he really did hurt his leg in July, even before he fell at the park? What's it all mean?'

'I don't know,' said James heavily. 'But Sirius, I'm starting to think I don't want to know. Peter's right. Are we sure we want to get mixed up in all of this? Maybe we should just leave well enough alone.'

'Leave well enough alone?' Sirius cried, springing to his feet and not caring in the least that a pair of Ravenclaw fourth years shot him a most supercilious glare as they passed him on their way to lunch. 'What's well enough about it? Remus is in some kind of trouble, James! He's scared and he's trapped and he needs our help! He's our friend: we've got to help him!'

'P-perhaps we could tell a teacher?' Peter suggested timidly. 'I mean, if there's something really going on…'

'The teachers don't give a damn!' roared Sirius. His heart was hammering in his chest now, and there were blind spots in his eyes. 'Either that or they know all about it and they're not doing anything to stop it! Remember the first time he disappeared, right near the start of first year? McGonagall said it was none of our business!'

'I don't remember that,' James said, frowning perplexedly. He was on his feet now, too.

'Oh, well, you and I weren't on speaking terms yet,' Sirius said with a broad, dismissive sweep of his arm. 'I told Remus about it. None of our business indeed! I'm going to find out what's going on and I'm going to stop it, or I'm going to die trying, do you hear me?'

'I hear you, mate,' said James. He reached out and gripped Sirius's shoulders, fixing determined hazel eyes upon him. 'Of course we've got to stop it. Even if it's dangerous. Remus is our friend and we've got to stand by him. But raging around isn't going to help anyone, is it?'

It was a wonderful thing, the calmness in James Potter's voice. It was as if he was a touchstone of clarity in a sea of chaos. His hands were steady; the fingers braced against Sirius's arms were sure. James believed him, and James was going to stand by him in this. Sirius felt his pulse slowing a little, and the wrath abated a little. He didn't need to be angry, because he wasn't fighting this battle alone. They'd work it out together, he and James.

'You're right,' he said at last, the words coming out in an exhalation that released tension Sirius hadn't even realized he had been carrying. 'You're right. We need to be calm about this. Sensible. We need to approach it logically, like…'

He laughed, a sudden and unexpected guffaw that shook his diaphragm and renewed his resolve. James, cognizant of the fact that his hold was no longer needed, released Sirius's shoulders and grinned quizzically at him.

'Like what?' he asked.

'Isn't it obvious?' Sirius asked, still chuckling. 'Like Remus would.'

~discidium~

Peter told Professor McGonagall that he was suffering from loose bowels, and he was therefore dismissed from Transfiguration. Sirius had to admire the portly boy's inventiveness. Given his dietary habits the excuse was beautifully believable, and Pettigrew delivered it with just the right amount of distended wriggling. Once he was off to resume surveillance of the hospital wing, Sirius was able to sit more or less still and pretend to pay attention to the lesson.

As soon as the class was dismissed, however, he tore off after Peter. James followed, weaving between their classmates in order to catch up. The moment they appeared in the empty corridor, Peter came waddling out from behind a pillar, holding the Invisibility Cloak at arm's length.

'Well?' asked James. 'What did you see? Did Remus come out?'

Peter shook his head. He looked profoundly unhappy. 'You're not going to like it,' he mumbled.

'Like what?' asked James.

Sirius growled, raising himself to his full height and bearing down on Peter. 'Did you doze off or something, you dunderhead?'

'No!' Peter exclaimed indignantly. 'No, I didn't. But a girl came by to ask the matron for a jar of Bubotuber ointment and I got a look inside.'

'Well, that's great,' James said, clearly puzzled. 'Why wouldn't we like that?'

'Were you seen?' demanded Sirius. Peter was all right, but it was so frustrating when he mucked things up. He just didn't have a knack for this sort of subterfuge, and that was why he'd never be a proper mischief-maker. And he didn't have much of a spine, either.

'No, I wasn't,' said Peter. 'I was under the Cloak the whole time until I saw you coming. But I saw inside, and Remus wasn't there.'

'He wasn't there?' asked Sirius. 'But I saw him go in.'

James groaned. 'He must have left while we were at lunch,' he said. 'Blast and botheration: we never should have let the guard lapse. It's one of the very first rules of surveillance, you know: never, ever let the guar—'

'Hush!' Pettigrew said, putting a finger to his lips. On the other side of the hospital wing door the clicking of the matron's shoes was heard. There was a little soft shuffling and a noise as if someone had bumped into something.

'Steady there, dear,' Pomfrey said.

Then they heard a familiar voice mumbling, 'I'm sorry, Madam. I didn't mean to.'

'Nonsense, Remus,' she clucked gently, as if there had been any doubt as to the speaker's identity. 'It's not my toe you stubbed. Come on, now. You'll feel better for a nice hot soak…'

There was a noise of a door closing and the matron's feet moved away. As one, the trio exhaled.

'All right, so he's in there,' James said. 'Peter must've got it wrong.'

'I didn't!' Peter protested. 'I saw all of the beds and he wasn't in any of them! I swear he wasn't.'

'Then she's hiding him somewhere,' said Sirius. He didn't always have the greatest respect for Peter, but the kid did know what Remus looked like. 'Maybe in a secret room or something. Why would she have him in a secret room?'

'We don't know that she does,' said James. 'Maybe he was in the loo or something when Peter looked in. Anyway, now we know he's here we'd best take it in turns to keep watch, just in case he does leave or someone comes for him or something.'

'Who would come for him?' Peter asked worriedly.

'That's what we're trying to find out,' James explained, and he managed to do it without sounding too annoyed. Sirius had to admire the patience James and Remus seemed able to muster where Peter was concerned.

'I'll watch,' he said. 'You two go and work on Pettigrew's Charms homework and then get some supper. James, you can come and relieve me at nine o'clock. Take the first night shift.'

'Fair enough,' James said. 'Only I'll be napping instead of tutoring, Peter. Fair warning.'

'I don't mind,' Peter said. 'Remus will help me when he comes back.'

If he comes back, Sirius thought grimly as the others moved off. Then he shook off that thought. It was foolish. Remus always came back. Every few weeks, regular as clockwork, he went away and then he came back, and more often than not he was hurt and he was always sickly and it just didn't make sense.

He swung the Cloak about his shoulders and settled down on a nearby plinth to wait. That, at least, was going to end tonight. He was going to figure this out.

~discidium~

Sirius must have dozed off, for he awoke with a start when the door to the hospital wing opened. Frantically he checked that he was still hidden. The Invisibility Cloak had not slipped off while he slept, though his backside was aching from prolonged contact with the marble. He scrambled to his feet as Madam Pomfrey came out into the corridor. She was carrying her wand in one hand, and with the other she reached back into the darkened ward to usher out a slight figure shrouded in a cloak that was rather on the short side. Sirius felt his pulse quicken as he realized it was Remus.

The matron put her arm around the boy's slight shoulders and steered him down the corridor. Breathless, Sirius followed. They descended a staircase and turned a couple of corners, and then Pomfrey stopped at a heavy oaken door. She opened it and the hallway was filled with the smell of autumn sunshine. It was one of the side doors that led out onto the grounds. Sirius took three long leaps to close the distance between them, slipping out just before Madam Pomfrey closed the door.

Remus seemed very nervous as he walked beside the matron. He kept looking back over his shoulder, staring up at the castle as if he expected to see a phalanx of archers waiting to shoot at him. His face was very white now, and there were two brilliant pink spots on his cheeks. He was unsteady on his feet, and he leaned heavily against Pomfrey.

Sirius expected them to make for the path that wound down to the gates, and so he was surprised when Pomfrey turned to the right instead, starting across the lawn towards Hagrid's cottage. Surprise shifted into alarm when he realized that she was guiding Remus straight towards the Whomping Willow.

The tree certainly could have caused the bruises, Sirius realized. Remus was following meekly, as if he knew precisely where they were going. Did they do this often? Every time Remus disappeared? And why?

Pomfrey did something with her wand hand, but Sirius was right behind her and could not see. Then, incredibly, she stepped into the range of the tree's deadly branches, guiding Remus with her. Sirius felt a shriek of indignation building up in his throat. The moment that Willow tried to take a swipe at his friend he'd dive in and snatch Remus away from the silly witch and he'd—

The Whomping Willow did not move.

Sirius was so busy staring up at the inexplicably motionless branches that he almost didn't see Pomfrey disappear down a hole cleverly hidden by two large, looping roots and the overgrown grass that, of course, Hagrid could not cut. Sirius shuffled forward, transfixed, as Remus – with a last, fearful glance at the castle – scrambled after her.

He was almost at the hole himself when the tree suddenly sprung to life. A slender tendril struck his cheek and he jumped back with a yelp as he was narrowly missed by a branch thicker than his waist. The Willow, of course, did not rely upon sight to guide it. It could sense his presence and it was attacking with vigour. Sirius scrambled back to safety, the Cloak falling to his shoulders as he did so.

Once he was out of range and the tree calmed itself, Sirius hurriedly covered his head again. He moved away from the tree and sat down in the grass to wait.

He did not have to wait long. An arm appeared, prodding at the base of the Willow. Again it froze, and Madam Pomfrey climbed out of the hole. She fixed her cap, which had gone slightly askew, and brushed earth from her robes. Then she started back towards the castle. Alone.

Sirius watched her go, startled and bewildered. The matron had taken Remus, who was obviously ill and weak, out of the hospital wing. She had led him down a hole underneath the Whomping Willow – a hole that until today Sirius had never even noticed. Then, inexplicably, she had left him there.

It didn't make sense. None of it made sense. Question after question arose, and there was never any answer. Sirius could feel his frustration mounting. It was at this point that he usually liked to go and find someone to hex, because at least then he felt like he had control over something, but he had other business tonight. If Remus had gone into the hole, it only stood to reason that he would have to come out. Eventually. And Sirius Black was nothing if not stubborn. He would wait.

So he waited. And waited. And waited. The sun set, and the twilight faded into darkness. It was a clear September night, and the stars were bright above. From Hagrid's hut came a low, mournful howl. Poppet, Sirius thought. He could hear an owl crying out far above, and he wondered whether Hermes would be out hunting tonight. He liked to think that Hermes got in as much of that sort of thing as he could while they were at Hogwarts. The hunting in London must be dismal: all those electric lights to befuddle an owl, and nothing to catch anyway but scruffy brown rats.

Sirius got tired of sitting, and lay down on his stomach, not really caring that his feet poked out from under the Cloak. Nobody could see two black shoes in the midst of a dark lawn at night, anyway.

A silvery light was rising over the Forbidden Forest. Sirius rolled onto his back, watching as the moon climbed higher. He found himself absentmindedly naming the features of its face that they had been studying so carefully in Astronomy the night before. Theophilus Crater, Arzachel, the Mare Nubium, the Mare Humorium, Grimaldi…

He sat up straight, staring at the ivory orb. They hadn't seen Grimaldi last night. It had been hidden in the earth's shadow. It was the very leftmost crater on the near side of the moon, visible only when the moon was full. Sirius only knew about it because the name was so similar to the name of the street on which he'd grown up, and he had always thought it funny that Grimaldi was nothing but a great, big vacuous hole in a cold bit of rock hundreds of thousands of miles away from earth.

Off in the glowing warmth of Hagrid's home, Poppet howled again. Sirius could hear the groundskeeper scolding her fondly, but he didn't try to make out the words. The howl sent a shiver up his spine. The moon was full.

Sirius felt his chest grow tight. His heart was no longer beating, but palpitating painfully under his breastbone. His throat was closing so that he could not breathe. Suddenly a thousand little clues fell into place. Every few weeks Remus disappeared. He came back ill and weak and wounded. It happened at school. It happened at home. He was covered with scars. He was frightened, ashamed, like someone hiding a terrible secret. He had to be taken from the school at dusk, and shut up in a hole underneath a violent tree. He had stumbled in the Forbidden Forest while they were talking about part-humans...

And Sirius remembered the cellar door. One night, while he'd been visiting Remus in Cornwall, he and James had crept out of bed. They'd nicked Mr Lupin's wand and snuck downstairs, and they'd unlocked the cellar door. They hadn't got any farther than that, but Sirius remembered how the back of the door had felt under his palm. Deep, parallel grooves dug into the wood, crossing one another over and over again as if something with great, vicious claws had pawed at the door in an attempt to break free.

Claws. Scars. Secrecy. And the moon was full.

His hands were trembling. The breadth of the conspiracy was beginning to dawn upon him. He had always known that Remus was keeping a secret, but he realized now that Remus was not the only one. His parents knew, of course. Pomfrey knew. And McGonagall. She knew: she had tried to protect the secret when Sirius had first asked about Remus's disappearance. It stood to reason that Dumbledore knew…

Sirius turned again, his whole body pivoting so that he was once again staring at the tree. His jaw was slack and his eyes were wide. The Invisibility Cloak was now puddled about his waist, but he neither noticed nor cared. The Whomping Willow stood silhouetted against the inky indigo sky, its branches gleaming in the light of the full moon. And somewhere beneath there, shut up so that he could not attack anyone, was a quiet and unassuming boy who by now was not one of those things: neither quiet, nor unassuming, nor indeed a boy.

Horror and astonishment and pity and sorrow all raged for purchase within him, but all that Sirius could feel was the hot glow of enlightenment. It was as if a new understanding of the world around him had been unlocked in a sudden devastating stroke, and he didn't know what he should feel or how he should react or how he was ever going to help James and Peter to see the truth. He could not move, nor speak, nor think. His entire existence had been distilled into a single crystalline truth, and in that moment he could neither embrace nor reject it, but could only see with excruciating clarity.

Remus Lupin was a werewolf.