A/N: I am so sorry – I know this chapter has been more than a fortnight in the works. I do hope it is worth the wait. The next instalment will not be nearly so far off – I won't give a promised date as I don't want to disappoint everyone after the madness of the past few weeks, but I'm setting my personal goal for under a week. Thank you to everyone who reviewed – it is so encouraging and gratifying to see readers' responses! A few review replies below… otherwise – enjoy! And a HUGE thank you to Mizuraikage, who's helpful message allowed me to finally sort the issue with fanfiction's uploading!

Babascoop: Thank you again for your review! I'm glad you thought Remus's character was a bit more multi-faceted – he and Sirius will be new additions to our POV characters from here on out. I find his decade-plus gap from Harry's life most interesting… and we'll be slowly exploring that, among other things, as we move forward.

BlueWater5: Thank you for your review! The information on the patronus charm is canon – the charm is considered to be above N.E.W.T. level, and thus not generally taught at Hogwarts except under special circumstances. That said, I agree with you that an uncanny number of D.A. members and Order members can perform the charm. The Order explanation is simple – it is their primary method of emergency communication, so Dumbledore obviously ensures that everyone who is capable of performing the charm can do so. The D.A…Harry works quite hard on getting everyone he can to perform the magic, even though they are all quite young and at varying levels. A lot of the students are successful… but then, they are not faced with a dementor or lethifold in the classroom, so it was hardly under true circumstances. Only Ginny, Ernie, and Luna (and obviously Ron and Hermione) are later confirmed to be able to do it in front of a dementor for certain, although I suppose it's theoretically possible that others would also be capable.

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DISCLAIMER: Any and all familiar characters and story lines are the property of the wonderful Joanne Rowling, in whose world I am honoured and privileged to have an opportunity to play for a while.

Chapter 6: Custodes Lucem Et Obices ad Tenebras

Albus returned from the Ministry past eleven, exhausted and frustrated with the long day's negotiations. He'd been furious to learn from Minerva that the Dementors had already arrived at the castle, without his approval. The ensuing argument with Fudge and his worries for Harry had left him with an uncharacteristic migraine.

'How is he?' he asked Minerva, as he stepped out of the floo and into his study at last. Minerva, who'd been sipping at a nightcap on the sofa, set the drink aside as she turned to face him.

'Rather irritable at being kept to bed and still running a slight temperature, but he should be alright in a day or two,' she replied. 'Poppy thinks he had probably contracted some mild illness beforehand. I cannot believe Fudge sent those horrible things up to the castle! Today could have been so much worse – it was a very near thing as it was.'

'I know,' Albus agreed, sinking heavily into the armchair and rubbing at the dull ache in his temple. 'I have already told Cornelius that they cannot be allowed to enter the grounds again. I will agree to let the Ministry station Dementors at the gates and perimeter… but I cannot abide their presence so near the school and students. It is against my better inclination even to consent to their placement in Hogsmeade. However, allowance must be made, I suppose, for the safety of everyone. I freely admit it does little to quiet my own discomfort.'

'I'm sure,' added Minerva darkly. She flicked her wand at the decanter, pouring a measure of scotch for Albus. He took the floating glass from mid-air with a grateful inclination of his head.

'Is Harry asleep?' Albus asked as he took a pull from the drink.

'Yes,' Minerva replied. 'Remus brought him up some supper a few hours ago, and he said he drifted off around half past nine. I haven't wanted to wake him… he'll need a fever reducer in the night, but otherwise I thought it best to let him rest for a while.'

'Of course,' Albus agreed. He sighed. 'We will have to address the Dementors. I'm sure Harry will have questions.'

Minerva grimaced, swirling her own scotch. 'Yes,' she said. 'He told me… I'm not sure what, to be honest. But he said he heard a woman screaming, when the Dementors approached him this afternoon. Remus said he'd repeated the story to him. He says Harry believes it was a woman begging for her life.'

'Lily,' breathed Albus, very quietly.

'I expect so, yes,' agreed Minerva. 'I don't know that Harry has realised it, at this point. But undoubtedly he will figure it out eventually. We must ensure that he does not come into contact with those horrors again, Albus. No child needs to relive their parents' murder.'

'Yes,' Albus agreed. 'But I don't know that it is so easily forgotten… memories have a way of resurfacing, and our worst more than the rest. I think we should be prepared for the conversation, whether Harry happens upon the Dementors again or not.'

Minerva sighed, but did not contradict him. They sipped their drinks in silence for a few minutes, each lost in their own thoughts.

'Did you speak with Remus about the position?' Minerva asked, changing the subject. 'He was rather drawn himself tonight, and I didn't get the chance to ask him before he set off for bed.'

'I did. He is hesitant, as I expected he might be, but I am hopeful he will agree to fill the post before the summer is out. He would be an excellent addition to the staff.'

'Severus will not be pleased,' Minerva observed, a small smile creeping across her lips.

'Perhaps not,' Albus allowed. 'But Remus is more than capable, and Severus is a grown man. School boy grudges fade, in time.'

Minerva snorted, raising a supercilious eyebrow. 'If only that were true,' she said dryly. She drained the last of her scotch and cleared the empty tumbler with a casual flick of her wand, making to stand. 'I'll stay tonight, I think,' she added, making to dim the lights. 'In case Harry has trouble in the night.'

'I'm happy to have you, of course,' said Albus, finishing his own drink. 'But I can manage Harry if you'd rather get your rest.'

'Don't be silly,' said Minerva, already dousing the candles on the mantle. 'You've had quite a long day yourself. And I expect Cornelius was trial enough for one day. You ought to come up to bed.'

Albus nodded as he got to his feet, and followed her up the staircase.

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Harry's fever was nearly gone by the following morning. Madam Pomfrey, however, to Harry's great consternation, insisted that he spend another day in bed and on her potions, 'just to be safe.' No amount of needling Dumbledore or McGonagall could convince them to free him from his jail, though McGonagall did allow him to revise his Potions materials from bed.

Dumbledore spent much of the day keeping him company, working on some of his own paperwork while Harry studied, and occasionally breaking the monotony with conversation. Harry rather thought he was feeling guilty for having been away at the Ministry most of the previous day. It was not until after lunch that they came around to the subject of Dementors once more, when Dumbledore admitted to Harry that they would be stationed at the entrances to the grounds for the foreseeable future, though not permitted to come near the school or students. Harry was not happy with the idea, and he didn't think the headmaster looked particularly pleased either.

'What exactly are Dementors, sir?' Harry asked, as Mina popped out of the bedchamber with their empty trays.

Dumbledore sighed. 'An interesting question, Harry. But, I am afraid, one without a simple answer. Dementors belong to a class of magical creature that we sometimes refer to as "non-beings." You have not, of course, had Care of Magical Creatures yet, but perhaps you have come across the term in Defence Against the Dark Arts?'

Harry gave him an incredulous look. 'From Lockhart or Quirrell, professor? You must be joking. The only dark creatures we ever studied were pixies… and that was a complete disaster.'

Dumbledore chuckled, though he seemed a bit sad. 'So I have heard,' he admitted. 'Alas – pixies are not truly dark creatures in any case… notorious pranksters, to be sure, but they rarely cause any significant or lasting harm. Dementors, however, are a different case entirely.'

'So what are non-beings then, sir?' Harry asked.

'Non-beings are a group of magical creatures that are not truly living and yet not dead. They are apparitions, for want of a better term, capable of interacting with the living in a way that true spirits, or ghosts, cannot. There are a number of creatures which fall into this group, some of which are more harmful than others,' the headmaster explained. 'Actually, Dementors are not the only creature thus classified that you have encountered in your time at Hogwarts.'

Harry wracked his brains as Dumbledore smiled expectantly at him. A creature that wasn't quite living and not dead… that interacted with people…

'Peeves?' he guessed. Dumbledore beamed.

'Indeed,' he agreed, nodding his head. 'Very good, Harry. Poltergeists too belong to the non-being family, though of course they a very different sort of phenomenon then Dementors. Non-beings are rather broadly classified, but they all share certain similarities. They cannot be seen by Muggles for instance, except in very rare cases, although Muggles can sense them and feel their effects. They are also considered to be amortal.'

'Amortal?' Harry repeated, confused.

'It is a term that refers to an entity that is not born, and thus cannot be truly killed. Non-beings are created from and thrive on human emotion, so their numbers can always increase. Some describe their existence like an invasive plant or a fungus.'

'So… so you can't kill Dementors?' Harry asked in clarification, feeling his heart sink a little.

'Not in the traditional sense, no,' Dumbledore agreed. 'We normally keep our Dementor population isolated at Azkaban, as a means of protecting society and as a way to keep their numbers at a controllable level, although this in itself has its own set of complications.'

'Remus mentioned that,' Harry said. 'Why Azkaban? Is it just because the Ministry thinks it doesn't matter so much what they might do to criminals?'

'Not solely, although that certainly plays a role' Dumbledore admitted. 'The Dementors are believed to have come from Azkaban. The island is often considered their origin – their birthplace, for want of a more descriptive term.'

'What, for all the Dementors in the world?' Harry asked, surprised.

'Well, all the Dementors in Britain,' clarified the headmaster. 'It is not clear whether they had existed before in this world, although there are legends that predate what is certain. Azkaban has a very mysterious history. The island was first discovered in the late 15th century by the Ministry. But it had been occupied and in use for many decades beforehand, by a dark sorcerer named Ekrizdis. Ekrizdis built the fortress, and used the island to lure passing Muggle ships from the dangerous waters. He tortured and murdered hundreds of sailors, practising the darkest of magics. When he passed away, the concealment charms he'd placed to secure the island's secrecy from the wizarding world began to fade, and Azkaban was discovered. The Ministry wizards who arrived to investigate found the Dementors at the fortress. Nobody knows exactly how they came to be there. For several hundreds of years, the Ministry chose to leave the island isolated, not wanting to disrupt the colony or feel their effects. But in 1718, our Minister for Magic, a man named Damocles Rowle, decided that the Dementors' presence could be put to use. He elected to turn the fortress into a prison, and send wizarding criminals to serve their sentences in the Dementors' presence. Thus, Azkaban Prison was created.'

Harry shuddered. An island teeming with those horrible creatures… he could understand, now, why Hagrid thought Azkaban such a terrible place. It would be intolerable to be in their presence every hour of the day.

'And they're to stay here, sir?' Harry asked.

'Outside of the grounds, but yes, Harry, they will be here until Black has been apprehended,' Dumbledore confirmed, looking quite grave. 'I am not happy about it either, but Cornelius and I are at least in agreement that the school's safety, and yours, particularly, must take precedence.'

Harry sighed. 'Well, I guess with so many looking for him, it shouldn't be long until he's caught again.'

'Let us hope not,' Dumbledore said, smiling a little. 'Now, I think perhaps you ought to take these and have a bit of a lie down, before Madam Pomfrey has both our heads,' he said, nodding at the potions on Harry's bedside table.

Harry scowled. 'I'm not even feeling ill anymore, sir,' he complained. 'And I don't want to go to sleep again.'

'Cheer up, Harry,' Dumbledore said, uncorking one of the phials. 'It's only until tomorrow. I dare say you'll survive one more afternoon of rest.'

'I might, but then I've got my Potions exam to look forward to, haven't I?' Harry grumbled as he drank the phial down. His eyes felt heavier almost at once. He suspected one of the adults had mixed in a sleeping draught.

'I'm sure Severus would be glad to give you a bit of time to recover,' Dumbledore assured him, passing over the next.

Harry wanted to disabuse Dumbledore of this foolish notion… but found he was too sleepy already.

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Severus was sieving a fresh batch of armadillo bile when he heard a sharp knock at the laboratory door.

'Enter,' he called to his visitor.

He knew it would be Albus, even before the man entered the office. Sure enough, the headmaster swept into the room, brilliant silver robes flowing about him and sharpening his resemblance to Merlin.

'Good afternoon, Severus,' Albus greeted, seating himself casually on the edge of the work table closest to the Potions master's station and popping a sherbet lemon into his mouth.

Whatever the resemblance, Severus was fairly certain Merlin himself was never quite so eccentric.

'Albus,' Severus acknowledged with a stiff nod. He finished his task and set the bowl aside, turning for the basin to clean his hands. 'To what do I owe the pleasure?' he asked when Albus had still not spoken his purpose, closing the tap and reaching for a tea towel.

'Ah, a bit of this and that, my boy,' the headmaster said airily, twinkling as Severus seated himself back in the chair he'd been working in. 'I wanted to speak with you about Harry.'

Severus scowled. 'What about him, precisely, headmaster?'

'Is it quite necessary to force him into sitting this examination?' Albus asked, fixing Severus with his piercing stare. 'We gave all the children a reprieve this year. I rather think that should include Harry. Him, perhaps, most of all.'

Severus' scowl deepened at the unsubtle reminder of the boy's foolhardy actions at the end of term. 'I cannot agree, headmaster,' he said through gritted teeth. 'It was you, after all, who insisted so passionately only last summer that Potter must be taught all we had to impart, and forced me into twice weekly lessons with the brat. I find your current attitude beguiling, given the intensity of your determination last year.'

'Oh, I still believe we must do all we can, Severus. The current state of things since Black's escape only furthers my conviction on that score. But I hardly think a formal examination necessary to commence the summer schedule.'

Severus considered Albus, still scowling. 'Perhaps that is your feeling, headmaster,' he allowed, 'But I believe it is my decision that counts, in this, as it is my subject, and under my jurisdiction. Potter's marks for the term have already been submitted – the examination will not affect his performance for the year. He bears no academic consequence beyond the setting of his summer schedule. Which, as his instructor, it is well within my discretion to determine. If the brat has chosen to complain now, no doubt it is because he has failed to do the required revisions in time. Potter knew the terms of the arrangement when we spoke at the end of the term. I will not alter my requirements just because he has found lazing about a more prudent use of his summer thus far.'

'The terms of your arrangement?' Albus echoed. 'What arrangement would that be, Severus?'

Severus cocked his head, considering Albus with a calculating gaze. 'Has Potter not said?' he asked.

Albus merely stared back, frowning slightly. Severus smiled a little. This was certainly an interesting development. He savoured the moment a bit – it was not often he found himself in possession of information that the headmaster did not know.

'I spoke with the boy after his… interesting display of wandless magic. His several displays, in fact. I was intrigued,' he began.

'As were we all,' said Albus, nodding his agreement. 'A most interesting and extraordinary display of power. Although, as I have said before, Harry is a uniquely talented wizard in many ways.'

Severus rolled his eyes. 'I shall ignore the debate on the merits of that claim for now, headmaster,' he said dryly. 'In any event, I find Potter's affinity for wandless spells most interesting. We have seen yet another little display just this past Sunday. But, thus far, he seems to perform this magic in times of great stress, or dire circumstances. Not unusual, given the close affinity of wandless casting and emotional response – but he will continue to tire and drain his core whenever he performs such feats, unless he is properly trained in the subject. If he has a true talent for it, and not merely an inability to stifle his emotions which I still suspect might be the case, it could be a useful skill in future.'

Albus was smiling now. 'A thought I have had myself,' he admitted. 'Though I was intending to wait a year or two to discuss it further with him, until his magical core was a bit more mature. Are you suggesting I take up his instruction in wandless magic this summer?'

Severus smirked. 'That should be quite unnecessary,' he said, deliberately making his voice as light and careless as he could. 'As I have already informed Potter that I shall be instructing him in the art.'

Severus' momentary triumph in shocking the headmaster so completely began to fade as Albus' eyes started to twinkle in such glowing satisfaction it almost cost him his lunch.

'What excellent news, Severus!' Albus exclaimed. 'I cannot tell you how it pleases me, my boy, to hear you have offered to take a more active role in Harry's life.'

'In his education, Albus,' Severus corrected immediately, returning to his usual sarcastic tone. 'In his education only. And it is as much in my interest as his… I suspect there is far less a chance of his exploding my classroom with basic wandless magic than his abysmal attempts to brew, and I rather think teaching a different subject for a time will break the monotony nicely.' He shot a pointed look at the headmaster.

'I daresay it will,' the headmaster acknowledged, still twinkling madly at him. 'But surely you are not intending to give up Harry's education in Potions as well? There is time enough for a little of both, I should think.'

Severus rolled his eyes. 'Just how much of my own holiday am I expected to devote to the brat, Albus?' he asked in annoyance. 'I have told Potter that if he successfully performs on his Potions examination, I will tutor him in wandless magic over the summer. That is all I intend to teach him.'

Albus looked at him seriously over the tips of his long fingers, pressed together at his chin. Severus could see he was still sucking that blasted sherbet lemon.

'I wish him to continue studying Potions,' Albus said at last. 'His performance and confidence were both well served this past year after the summer lessons. But I am in agreement with you that he has shown enough skill to merit instruction in wandless magic – or at least enough that we should make the attempt and see what he is currently capable of. So the question becomes, Severus, do you wish to instruct him in wandless magic? Or shall I take the task in hand?'

Severus glared back for a long moment. He knew Albus could teach the brat just as well – better, perhaps, as his knowledge was certainly greater than the Potions master's. He knew Albus would teach Potter, if Severus did not – whatever tale Severus might have fed to the boy about the many demands on the headmaster's time this summer.

But he wanted to do it.

'I shall do it,' he spat finally, hating himself for the admission.

'Splendid!' Albus said, clapping his hands together in satisfaction. 'Well then, I will offer no further objection to your scheme to have Harry sit the Potions examination –'

'How thrilling,' Snape grumbled.

'But I must insist you put it off for a few days.'

Severus crossed his arms, his glare back in place. 'And why is that?' he asked sourly. 'Potter has known for weeks that he's to sit the exam tomorrow. If you're telling me he needs additional time to prepare, I'm afraid I'm not going to –'

'He has been ill, Severus,' Albus said. 'Surely you can make some allowances.'

Severus waved an impatient hand. 'Yes, I heard about the Dementors, Albus,' he said dismissively.

'Poppy has kept him to bed until tomorrow,' Albus continued. 'I cannot think it fair that he should be worried he must sit your exam in the morning while he is supposed to be resting.'

'Two days in bed to recover from a Dementor attack?' asked Severus, frowning. Come to think of it, he hadn't yet seen the boy wandering the castle corridors. 'That seems rather excessive, even for Poppy.'

'Yes, well, he seems to have been fighting something off already,' Albus explained. 'And I think the Dementors affected him more significantly than what might be considered usual.'

'How so?' asked Severus, though he was not particularly surprised, with the boy's history.

'He passed out from the interaction – it took Mina and Minerva more than fifteen minutes to revive him to consciousness. And he states that he heard a woman screaming, pleading for her life, when they approached him.'

Severus felt cold and numb himself… he could see it again, in his mind's eye: the broken, crumpled form of Lily Evans on the nursery floor, almond green eyes open and lifeless; the baby, wailing and bleeding in the cot behind her.

He swallowed, not looking at the headmaster.

'He can have until Thursday,' he said gruffly, busying himself over the bowl of armadillo bile again to avoid Albus' eye. 'But do know that I'll adjust the tested materials accordingly.

'I would expect nothing less, Severus,' said Albus knowingly. He popped off the edge of his work table, smoothing the front of his robes. 'Well, I ought to head back,' he said in a brighter voice. 'I shall see you at dinner later.'

Severus hesitated a moment, as Albus turned toward the door.

'Did you tell him?' he asked quietly. The headmaster turned back, his eyes inquiring.

'Tell him what?'

'Did you tell the br – Potter. Did you tell Potter that he was almost certainly hearing Her?' Severus asked. He was disgusted to find his own voice a bit thicker than usual.

Albus' eyes were sad, and full of understanding. Severus could not stand the scrutiny. He turned away and back to the bowl of bile, though there was really nothing to be done to it anymore.

'No,' the headmaster said quietly. 'I'm sure I will have to, eventually. He may even figure it out on his own… but I could not lay another horror on his shoulders just now.'

Severus nodded once, stirring the foul liquid before him unnecessarily. He felt a long-fingered hand close briefly on his shoulder, and then headmaster swept from the room without another word.

Severus was grateful. There were no words that could have offered comfort in this moment.

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Harry sat his Potions examination on Thursday morning. Snape had given him one extra day, after he was finally released from his imposed bedrest. Harry rather suspected that the delay was McGonagall or the headmaster's doing, because Snape had certainly not been particularly gracious about the announcement at breakfast.

The test was just as trying as he had expected and dreaded it would be. There were nearly one-hundred written questions of various length, and then Snape had him brew two potions – one of which he'd seen before, and one that he had not – during the practical portion of the examination. Harry found out quickly why the dragon gloves were necessary, as the very first ingredient in the unknown brew was diced liver of spiny pufferfish, and Harry had to dissect the disgusting, prickly creature in order to reach the organ. Snape, who sat flipping through some journal at his desk while Harry worked, casually reminded Harry as he made for the supply table that the professor had laid out that pufferfish were not only covered in delicate spines, but also highly poisonous.

At least he'd spoken up before Harry had begun to cut.

Six hours later, Harry finally left the dungeons. He was ravenous (having worked straight through lunch) and quite sweaty from his feverish brewing, but overall he thought the examination had gone rather well. He'd felt confident in the written portion and – though he worried the fertilising elixir could have been a shade lighter – he was reasonably confident that both his practical efforts were passable. Snape gave a completely inscrutable nod at the cauldrons when Harry announced he was finished, and sent him off with the pronouncement that he'd have Harry's marks by supper.

He collapsed gratefully onto the sofa in the headmaster's study. He was far too exhausted and famished for anything strenuous.

'Goodness, you look as though you've been in the trenches,' Professor McGonagall announced, sweeping down the staircase from the quarters above with a slightly worried frown.

'I feel like it too,' said Harry wearily. 'Just tired!' he amended quickly, as McGonagall's frown deepened and she hurried over to peer more closely at him. 'The exam was really tough. And I'm starving!'

McGonagall looked scandalised. 'Severus did not allow you lunch?' she asked, hands on her hips.

Harry shrugged. 'To be fair, I didn't ask. I just wanted to get the whole thing over with at that point.'

McGonagall shook her head in apparent exasperation, but called for Mina at once to bring up a few sandwiches and some iced pumpkin juice for Harry. He dug in immediately.

'You ought to rest a bit this afternoon,' McGonagall opined, seating herself on the ottoman. 'You don't need a relapse.'

Harry rolled his eyes, swallowing a particularly large mouthful of sandwich with some difficulty to hasten his protest. 'I'm fine, professor,' he insisted. 'And I've rested enough for the whole month at this rate. I wanted to go and see Remus this afternoon.'

'No cheek!' McGonagall reprimanded. But she smiled. 'If you're quite sure you aren't too tired; I think Remus was headed to the library after luncheon. You might find him there.'

'Brilliant!' said Harry enthusiastically. He scarfed down the rest of the food as quickly as he could, and pushed himself off the sofa again. 'Thanks for the sandwiches, professor. I'll see you at dinner!'

McGonagall nodded, and Harry tore off for the library.

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Remus was sitting at a long oak table, perusing a pile of carefully selected tomes, when hurried footsteps echoed off the marble floor. He looked up to see Harry rushing through the library toward him, beaming happily and looking quite relieved to have his examination finished. He smiled as the boy reached the table.

'Good afternoon, Harry,' he said. 'How did the exam go?'

'Pretty well, I think,' Harry replied, perching himself on a stool opposite Remus. 'We'll see though – Snape said he'd mark it before dinner.'

'I'm sure you did wonderfully,' Remus offered bracingly, clearing a bit of space so that they could see each other across the crowded table. Harry looked curiously at the titles of the books.

'Defence books,' he observed, eyes alight with excitement. 'Have you decided to take the post, then?'

'Not quite yet,' Remus admitted. 'But I'm considering it carefully. I looked out the library's offerings for some ideas about our lessons this summer, actually.'

Harry shifted a bit closer to the table, looking intrigued. 'What are you going to teach me?'

'Well, as I said before, I think we can decide on some of the curriculum together. The headmaster mentioned he's already gone over some defence work with you, and you're quite adept at the subject.'

Harry blushed. 'I dunno about that,' he said modestly. 'But I liked the lessons. Dumbledore mostly taught defensive spellwork – like duelling. I don't think Professor McGonagall was all that keen on it, but I thought it was brilliant.'

Remus smiled again. 'Well, Professor Dumbledore seems to think you're very skilled in that area. This summer, however, he wishes to use his own lessons with you to teach a different mixture of magics, with a bit less focus on combative spells.'

'What sort?' asked Harry, surprised. 'Isn't learning to fight the most important kind of magic to learn?'

Remus gave a deep laugh. 'Oh, Harry,' he said, still chuckling. 'Since I've got to know you over the past few weeks, you continue to surprise me. You share some similarities to James, but even more, I think, to Lily. And then, there is much about you that is uniquely yours alone. But that – that statement was all James.' He laughed again, not least because Harry was looking an odd mixture of confused and offended.

'What sort of magic is more important, then?' Harry challenged, when Remus had recovered himself.

Remus continued to smile, but did not give the secret away. 'I think I'll let the headmaster explain the details,' he said instead.

Harry sighed. 'Well, I'll ask him if I ever see him again,' he said, sounding a bit ornery. 'He's gone off to the Ministry again, I think. He'd left the castle before I even got up this morning.'

Remus sighed. 'I know it's hard sometimes, Harry,' he said in understanding. 'But this situation with Sirius Black has everyone on edge. Dumbledore is the most venerable wizard in Britain – possibly in the whole of our world, you know that. His assistance will be needed to deal with the crisis, not least because it is so closely tied with your safety. He would not go if he could avoid it.'

'I know,' said Harry in a small voice. 'It's just… I just got back. I wish I could see him a bit more.'

Remus reached across the table, taking Harry's small hand in his own. He gave it a light squeeze of sympathy and comfort. 'I'm sure he will be back in time for dinner,' he said reassuringly. 'Now,' he added, trying for light-hearted again. 'What say we talk about our lessons for the next two months? I was thinking we could do a bit more on duelling, since you seem to like it and Dumbledore will probably take your studies in a different direction… I'd like to teach you about dark creatures, but it'll take a few weeks to scrounge up some specimens, and that sort of thing is much better taught practically than out of a book. But we could –'

'I want you to teach me how to stop the Dementors,' Harry interrupted. 'Can't you show me that charm you talked about a few days ago?'

Remus hesitated. He had rather hoped Harry might have forgotten that conversation.

'Please?' Harry pressed.

'It is very difficult magic, Harry,' Remus cautioned. 'You are probably far too young to learn it yet. Most adult wizards have trouble with the patronus charm.'

'I'll work really, really hard, Remus,' Harry insisted. 'I don't care if it takes me forever to learn it – I just want to know how.'

Remus stared into the determined young face for a long moment, teetering. 'Very well,' he said at last. Harry broke into a beaming smile, but Remus held up a cautionary hand. 'I will teach you the incantation,' he clarified, 'And try and show you how to use the spell. But Harry – I make no promises that you will be able to perform it. And you must realise that casting a patronus outside of the presence of a dark creature is quite different from performing it under the circumstances you faced with the Dementors' advance. There is every possibility that you will not be able to do that, yet.'

'I understand,' Harry said quickly.

'Very well.' Remus began to dig through the nearest pile of books, emerging a moment later with a battered copy of Protection in the Face of Darkness, by Nimue Lacus. He handed the book to Harry. 'You might have a look at this, for a start,' he offered. 'Chapter Seven will tell you a bit about the spell.'

'It's ancient,' said Harry, flipping the book open delicately.

'Yes,' Remus agreed. 'The book itself is quite an old copy, but the history of the incantation is even older. This is but a written account of many oral histories, first recorded in the eleventh century, and there are many indications that the patronus predates even these. Many of our oldest protective and defensive charms are derived from the most ancient realms of magic.'

Harry, who had located the assigned chapter, read aloud: 'Custodes lucem et obices ad tenebras.' He looked up. 'What does that mean?'

Remus smiled, pushing over a blank sheet of parchment. 'Mark the page,' he suggested. 'And you can read it for next Monday and tell me yourself.'

Harry rolled his eyes. 'Homework already?' he complained, but the whinge was mostly teasing. He stuck the proffered parchment into the book to mark the place, and carefully shut the tome again. Remus saw his brow furrow, as one hand traced the golden letters of the author's name.

'Something wrong?' he prompted, when Harry looked up.

'Not particularly,' Harry said slowly. 'But… I think I know this name.'

'Nimue,' Remus clarified, not bothering to reference the embossed lettering. 'Yes, I'm quite certain you do know of her.'

'Who is she?' Harry asked. 'Has she written another of our textbooks or something?'

'No,' said Remus, still smiling. 'She did not even truly write this one; or, rather, we do not know if she did. Her name has been associated with this particular tome for centuries, though whether that is because she was in fact its original author or merely because legend enveloped truth, I do not know. She has been called a heroine, and equally a villain; treated in legend as both light and dark. She has been given many names – Viviane, Nyneve, Evianne… but her true name is believed, among wizarding folk, to have been Nimue. I believe Professor Dumbledore will talk to you further on the subject sometime this summer, if you ask him. He knows a great deal more of the history than I.'

'Ok…' said Harry, still sounding confused. 'But why would I know her?'

'Because,' Remus explained, 'Even among Muggles she is a legendary figure. In addition to her own substantial contributions to magic, she was married to the most influential wizard the world has ever seen.'

'WHO?' asked Harry, clearly growing irritated. Remus laughed at his frustration.

'Merlin, Harry.'

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Several hours later, Harry dropped into a chair at the long table in the Great Hall for dinner, looking forlornly at the empty place in the centre of the table.

He tried not to be resentful toward Dumbledore for his absence… Remus was right, of course. Dumbledore's eminence was bound to call him away from Hogwarts during such a time of upheaval in the wizarding world. Harry wondered, vaguely, what it must have been like for Remus and his father – and even Snape – to have been at school during Voldemort's reign of terror. Had the headmaster been frequently away, even during the school year? Had he been called on for more important tasks outside the castle walls? What was it like – to have grown up when the wizarding world was at war?

Harry couldn't imagine it. Except for the few months last year when Dumbledore had been temporarily relieved of his post, there had scarcely been a day when Harry did not see the headmaster presiding over the Great Hall in the evening. His presence was protection, strength and guidance. Without him… Hogwarts would not be Hogwarts.

Harry's musings were interrupted as a pale hand slapped a stack of parchment down in front of him. He started at the noise and followed the hand upward – to Snape's smirking face.

'Daydreaming, Potter?' the Potions master mocked.

'Er – no sir, sorry,' Harry mumbled, reddening slightly.

Snape snorted. 'Your Potions examination,' Snape stated, gesturing at the pile of parchment he'd set in front of Harry. Harry leaned over it with some trepidation. There was a lot of scarlet ink, but nothing was marked as wholly incorrect… not on the first page, at least. In the top right hand corner, there was a large letter 'E.'

'What – is that the mark, sir?' Harry asked in horror, pointing at the E.

Snape raised an eyebrow. 'Obviously,' he stated dryly.

'Er… so I didn't do well then, sir?' he clarified, crushed. He'd always known that Snape would set a difficult exam… but he couldn't believe he'd failed so badly.

Snape's brow arched even higher. 'What are you on about, Potter?' he asked irritably. 'You did… quite well, actually. Nowhere near perfect, mind you, but well enough that I believe we can continue with our arrangement for the summer schedule.'

Harry was confused. 'But – but I got an E,' he said dumbly. Snape stared back for a moment, then rolled his eyes impatiently.

'Wizarding marks do not match up to the Muggle scheme, you foolish child!' he snapped.

Harry felt indignant now. 'Well, how am I supposed to know that? All our exams and homework and everything have always been given a percentage score here, haven't they? I've never received a letter before!'

Snape sighed, pinching the bridge of his hooked nose between his thumb and forefinger. Harry rather thought it appeared he was giving the Potions master a migraine. After a moment, Snape seemed to collect himself again, and let his hand drop with a martyred expression of resignation. 'First through fourth forms at Hogwarts,' he explained, 'Are normally given percentage scores on examinations, quizzes, and other marked assignments. This scheme is changed in your fifth year, when you sit your O.W.L. examinations.'

'Ordinary Wizarding Levels?' Harry clarified. Snape's eyes flashed at the interruption. 'Sorry, sir,' Harry backtracked quickly.

'Yes,' Snape said stiffly. 'Ordinary Wizarding Level examinations are evaluated on a six-letter scale. O for Outstanding, E for Exceeds Expectations, A for Acceptable, P for Poor, D for Dreadful, and T for Troll.'

Harry held in his giggle at the last – there was no point in testing Snape's temper further when the latter was so uncharacteristically in a mood to share tonight.

'Your teachers will begin to evaluate your performance using the O.W.L. marks at the start of your fifth year,' Snape continued. 'However, I personally find the six-letter scheme a better indicator of student competence. And so, because this is not a regularly conducted examination… I chose to employ it here.'

'So… so I "exceeded expectations," sir?' Harry asked.

'That is not particularly hard to do when my expectations are that you will destroy the classroom,' Snape replied, sarcastically. He rolled his eyes as Harry's face fell. 'Yes, Potter, you earned an E. Which is not an easy feat, under my critique.'

Harry brightened at once. 'Brilliant!' he exclaimed. 'So, does that mean we can work on wandless magic then, sir?'

'It does,' Snape agreed in a bored tone. Harry noticed that his eyes grew cold and hard once more, as Remus came through the doors with Professor McGonagall.

'Good evening, Severus,' Remus said happily. He made for the chair to Harry's immediate right. Snape, giving Remus a murderous glare, did not return the greeting but glided more smoothly than a Dementor around the table to choose a seat as far as possible from his former classmate. Harry looked between them curiously, but neither offered any explanation. McGonagall seated herself in her usual chair, brushing a hand over Harry's untidy black hair as she made her way down the table. She clapped her hands over the wood, and dinner popped up at once.

'Aren't we waiting for the headmaster, ma'am?' Harry asked in confusion, looking toward the door in hopes that Dumbledore would soon sweep through.

'I'm afraid not, Harry,' said McGonagall, giving him a sad little smile. 'He's been delayed at the Ministry this evening, and I don't expect him back until quite late. Madam Pomfrey has set off on a few weeks of holiday and Hagrid is working on a project, so it is just us for the night.'

'Oh,' Harry said, a bit despondently. He turned for his roast chicken without much enthusiasm.

The little party ate without much conversation. Harry was tired from the long day, and even more so when he considered that he already had reading for Remus and revision for Snape due Monday next. He'd have skipped out on dinner entirely, but he knew if he did Remus would hover and McGonagall would have kittens. More than anything, he just wished Dumbledore was around.

At last, the meal had finished. McGonagall announced she was retiring early, to finish some paperwork up in the office, and Harry jumped at the chance to sneak away with her. Remus, who did not seem overly keen to remain alone with Snape, hopped up as well, mumbling something about heading back to the library and leaving the hall ahead of Harry and McGonagall.

'Don't forget to take that,' Snape barked at him as Harry pushed to his feet, nodding toward the inked-up exam papers that Harry had moved aside to eat. Snape appeared quite at his leisure despite his solitary place at the table, pouring himself another goblet of deep red wine and leaning back more comfortably into his chair.

'Yes, sir,' said Harry quickly. He gathered up the parchment and tucked the lot into his bag, next to the book Remus had lent him.

'Oh, and Potter?' Snape called, just as Harry reached the door. Harry turned back. Snape wore a somewhat evil smirk.

'You may have exceeded expectations today, but you will find that only outstanding is a satisfactory passing mark in my subject. I do not accept N.E.W.T. students who do not earn an O on their O.W.L., and the headmaster would prefer that you continue on with Potions at the advanced level. If you wish to have any prayer of doing so, you will have to continue your Potions instruction.'

Harry's jaw dropped. 'You mean I have to do summer lessons in Potions too?' he asked in horror. 'I thought you were going to do the wandless magic lessons instead?'

Snape sneered more widely. 'I assure you, I do not relish the thought. You shall be prepared for Potions on Mondays and Wednesdays, wandless instruction on Tuesdays and Thursdays. As a preliminary assignment, you can revise the corrections on your examination.'

Harry glanced up at McGonagall, who had stopped alongside him at the door, half-certain she must move to end this madness. But though the Gryffindor head was pursing her lips in apparent disapproval, she did not contradict Snape.

'Right, sir,' said Harry, defeated.

Snape inclined his head. 'Until Monday then, Potter. Nine a.m. sharp.'