Ginny wasted no time in cornering Harry on Saturday morning at breakfast, simply popping up in front of him as he entered the Great Hall and manhandling him over to the Gryffindor table. It was eight o'clock on a weekend, so the space under the red and gold banners was very sparsely occupied, and they had no trouble claiming a spot well out of the way of any other early risers.

"So what did Professor Dumbledore say?" Ginny demanded as soon as they slid into their seats.

"He said he'd look into it," Harry said.

Ginny scowled. "That's it?"

"Well, what did you expect?" Harry asked, a little defensive. "I told him that Penelope had the book, and that I was worried about her getting hurt. I'm pretty sure he believed me."

"Okay, that's good, I suppose," Ginny muttered, stabbing a spoon into her oats with enough force to clink against the bottom of the bowl.

"I'll let you know if it doesn't look like anything's been done by next week," Harry suggested.

"Make it tomorrow," Ginny said, pointing her spoon at him. Tomorrow seemed a little soon to expect action, but Harry agreed.

Perhaps he had underestimated Dumbledore, however. Later that day, when Harry returned to the common room, he saw Professor Flitwick speaking with Penelope by the fireside in low tones, some sort of privacy spell muffling their words. When he covertly spied on Penelope's dormitory again, Harry saw no sign of the book anywhere. Just to be certain, he checked a few hours later and observed the same result. Penelope, too, was not there—Harry overheard from Robert that she had been admitted to the hospital wing.

The rest of the month passed without any life-threatening excitement. Harry felt only mounting dread at the rapidly approaching holidays, however. He could not put his mind into his schoolwork—it all seemed absolutely trivial in the face of the threat of Voldemort, who was literally immortal, whatever technicalities Dumbledore liked to bring up in order to claim otherwise.

It was odd. He had never felt such existential terror as in the depths of the night, curled up in his bed and faced with—what had Dumbledore called it—that looming spectre of death? He had stood in front of Lord Voldemort himself with only a fraction of this fear.

On reflection, it wasn't odd at all. Harry would gladly go before the Dark Lord again, right this second, rather than stew in this miserable swamp of uncertainty. Over the course of term, cut off from contact with his enemy, Harry had lost his tenuous grasp on Voldemort's present goals and motivations. He couldn't predict what the Dark Lord would do next, couldn't know if he had changed his mind.

Because what if he had? What if his next words to Harry would be those fateful two? This time, Harry would have no power of love to shield him. There was only his horcrux, which was cold comfort. So what if some separate part of him could live on? Could that really be called survival?

He knew there was no point in worrying. If the Dark Lord truly had decided to off him, there was absolutely nothing Harry would be able to do to stop him. There was no magic he could learn in the span of three weeks that would make a single iota of difference.

For this reason, he found himself utterly unmoved by the announcement of a new duelling club. He had half a mind not to go, only Vince of all people had been terribly excited about it. Harry had never seen Vince excited about anything besides his next meal, so he felt it would have been rude not to join him.

That evening, half the school packed themselves into the hall, crowding around a raised platform draped in golden fabric.

"Do you reckon we'll learn any hexes?" Vince was asking Draco from up near the front. He and Goyle had elbowed a path through the crowd, leaving plenty of room for Harry and Draco to follow in their wake.

"Don't be daft," said Draco, puffing out his chest. "Duelling is about strategy and grace."

Vince grunted. "I thought duelling was about taking out the other guy."

"You've confused it with brawling. I don't know why I expected anything else." Draco sniffed and turned his attention back to the stage.

"I thought brawling was…" Vince slammed a fist into his other palm with a meaty thwack, peering at Harry for confirmation.

"I thought so too," Harry whispered, glancing bemusedly at Draco's back.

At this point, Professor Lockhart sauntered onto the stage, and an audible groan passed through the room.

"Figures," Harry muttered. There went any hope of actually learning anything. A scowling Professor Snape arrived next, his expression souring further as Lockhart began to pontificate. At length, they strode to opposite sides of the platform and bowed, though that was perhaps a charitable word for Professor Snape's jerky nod.

The Slytherins cheered as he ended the demonstration duel with a prompt disarming charm that sent Lockhart careening into the wall. Harry leaned forward in interest, wondering whether that had been a variation on the standard charm, or simply something that could be achieved with judicious application of will.

He was a little surprised that Professor Lockhart been taken so off guard. Surely the Dark Lord had not gone so far as to order him not to defend himself? Then again, it had only been the disarming charm, and he was already picking himself up off the floor.

"If I had wanted to stop you it would have been only too easy—however, I felt it would be instructive to let them see…" Lockhart was saying to Snape, whose jaw was so tightly clenched that Harry was expecting to hear a crack any moment.

"Excuse me, Professor, but how does one stop the disarming charm?" Harry asked Lockhart as he hurriedly climbed down from the stage and began to pair students off. The spell travelled quickly enough that it wouldn't be easy to dodge. Harry supposed a shield charm might work, but the shield charm put the caster on the defensive and had to be dropped in order to cast another spell, so he didn't think it would be very good in a one-on-one duel.

Professor Lockhart puffed up. "Ah, that's an advanced technique. Easy enough for somebody of my calibre, of course, but I'm afraid—"

"You interrupt the spellcast with your own spell," came Professor Snape's dour voice from behind them. "The duellist who allows his opponent to complete the spell of his choice unmolested has already lost half the battle. Mr Crabbe, Mr… you. You two. Attempt to disarm each other simultaneously."

Harry stood back from Vince, who suddenly looked nervous. They bowed. Professor Snape counted to three.

Harry whipped his wand forward and sketched a jagged angle through the air, like he was ticking a giant box. "Expelliarmus!"

Vince had hardly brought his wand up. He stared dumbly as a jet of red light arced across the room and sent him stumbling backwards, his wand flying out of his grasp.

"Or in this case, the whole battle," Professor Snape muttered, eyeing Vince critically. He gave Harry a curt nod before turning to supervise another pair.

"Sorry," Harry called out as Vince scrambled to recover his wand, which had rolled dangerously close to the feet of an adjacent group of students. "Accio Vince's wand," he tried. The wand rolled back in their direction, which he counted as a success.

They duelled again. This time, Harry hesitated a little, eager to see what Professor Snape had been talking about. The two disarming charms met in midair, as if magnetised, fizzling into a shower of red sparks. Harry felt his arm jerk, but he was able to keep his grip on his wand. A broad grin stole its way onto his face, only to be wiped away a moment later when Vince's next spell, a stinging hex, nailed him in the shoulder. He could feel it swelling up, itching something fierce, and forced himself to end the duel with another disarming charm.

"Stinging hex, really?" he muttered, rubbing at the irritated skin. Whenever Petri used to cast it on him, it would leave a shiny burn that smarted for a good ten minutes, but didn't swell. The presumably weaker version Vince had hit him with hurt far less, but the itching was almost worse than pain.

Vince shrugged. "Thought I'd change it up. Disarming charm's boring."

Harry supposed he couldn't argue with that, but on the other hand, his offensive repertoire did not exactly seem suited to a friendly duel.

In the next round, he tried the Full Body-Bind curse, discovering the hard way that naturally, a six-syllable curse took longer to cast than the five-syllable disarming charm. All the less savoury spells he knew had even shorter incantations, which he supposed must be by design.

The disarming charm, boring as it might have been, won him four out of five rounds, which he felt spoke well for its utility. He hadn't thought too much of it back when Professor Snape had taught it in Defence while Quirrell had been ill. Now he felt like he would never forget it.

"Again?" Harry asked as a disheartened Vince recovered his wand. Harry frowned. "Maybe we can switch partners?"

They walked over to where Draco was soundly trouncing Goyle. The blond boy cast his spells almost lazily, one arm crossed over his chest and his feet pressed together, like he was giving a recital. He caught Goyle's wand once again and threw it back to him.

"Ready for a taste of the floor?" Draco asked as Harry approached, raising one eyebrow haughtily.

Harry remembered with unease that Draco was under the Dark Lord's imperius curse and had already made an attempt on his life. On his guard, he clenched his fist securely around his wand and snorted. "You wish."

They each took ten steps back. Unlike Draco, Harry kept his feet spread apart, crouching slightly. They bowed, Draco with perfect form and Harry clumsily.

Then, "Expelliarmus!"

"Serpensortia!"

A thin black ribbon of a snake shot out of Draco's wand and was promptly blasted into the air by the disarming charm. It landed in a displeased coil, writhing every which way.

Draco hadn't cast anything else, eyes fixed on the snake he had conjured, so Harry cast the disarming charm again and sent him toppling to the ground.

"I win," Harry declared. He glanced back down. The snake was gone. To their left came a high-pitched scream. It was Lockhart, stumbling backwards as the confused snake wound underfoot. Professor Snape, who was on the other side of the room, crossed it at a leisurely pace, clearly in no hurry to alleviate Lockhart's suffering.

Despite his loss, Draco was laughing silently, one hand over his mouth as he dusted himself off.

"Look at that milksop," he said, dropping his hand and smirking at Harry. His face fell suddenly. "But you—you're not afraid of snakes then? You just ignored it."

Harry shrugged. "I like snakes. They're really very silly animals," he said, thinking of Shy's ridiculous runespoor with the cone on one of its heads.

"Silly?" Draco demanded, straightening up. "Snakes are noble creatures, deserving of respect."

Harry just grinned at him. "Silly," he insisted.

On their right, Vince and Goyle hadn't noticed anything amiss and were still going at each other with a variety of minor hexes that were most certainly not the disarming charm. Vince had a pulsing boil coming grotesquely off his nose and Goyle's eyebrows had grown past his chin. Of course, neither of them knew the counterspells to what they had cast, so they had to endure until the end of the club and face Professor Snape's sneering wrath as he sorted them out.

"That was fun," Harry told Vince as they exited the hall. He felt much more cheerful than he had going in, even though intellectually he knew that being able to win a duel against his yearmates meant nothing for his survival potential. Still, the idea of fighting for his life had gone from a nebulous horror to something more concrete, something exhilarating, even. If he was going to duel to the death, it was better to enjoy it than to suffer, right?

Harry was one of the few male students to appear again at the following week's meeting of the duelling club. The consensus among boys was that Lockhart was a disgusting fraud and Snape an unforgiving taskmaster. Luckily, the former was mitigated by the latter, as the first thing Professor Snape did was stun Lockhart and leave him collapsed on the ground. Seeing this, half the attending students fled the hall in disappointment, leaving much more room for Harry and the rest. Oddly enough, they were all Slytherins.

"As you can see, the stunning spell is an efficient means of disabling your enemies, as it renders them unconscious," Professor Snape said. "Regrettably, the effect is not permanent and will wear off after some time. The incantation is stupefy."

Three syllables, Harry thought. Very nice. Professor Snape demonstrated the wand movement, a helix that ended on a down swing, as if one were slinging a stone.

Gemma raised her hand. "Professor, how do we stop the spell if someone is attacking us?"

"The stunning spell is a hex," Professor Snape said, demonstrating the spell again on Lockhart's prone form, which jerked as the bolt of red light slammed into his side. "Unlike jinxes and many curses, it is an aimed projectile which is simple to dodge, as long as you are not taken unawares. While your opponent is foolishly casting the stunning spell, you may prepare a more effective attack. The disarming charm, for instance."

"Are you saying that we shouldn't use the stunning spell then, sir?" asked Pansy Parkinson.

"No Miss Parkinson, I have said no such thing. Duelling is as much a mind game as it is one of magical prowess. A spell that would be appropriate in one situation may prove to be a fatal mistake in another. Carrow! When would be an ideal time to use the stunning spell?"

Snape pointed at a sallow-faced Slytherin who was standing to another, seemingly identical girl. Carrow thought in silence for a few moments before she said, "When you're really close, or when the other person's running away."

"I should hope that none of you will be seen running away from a formal duel," Snape drawled, earning hesitant titters around the room. "There is always the option to forfeit. But you are correct, Carrow, that the stunning spell and other hexes of its class are most effective at close range."

Professor Snape paired everybody off just like last time, and Harry ended up across from Parkinson. They bowed to each other and promptly exchanged disarming charms. Harry managed to get a second one off slightly quicker than his opponent, and her wand went sailing into the air. He frowned, wondering if there might be a more efficient spell to transition into. The disarming charm ended with an upward stroke. If he could bring it back down—that was it—the stunning spell's helical wand movement was perfect.

Parkinson retrieved her wand and they started again.

"Expelliarmus! Stupefy!" Harry shouted, and to his gratification the stunning spell manifested from his wand as a strong red bolt. Parkinson dodged it with a shriek, recovering quickly enough to meet his next disarming charm with her own. They both paused for a confused second, surprised at having lasted so long, then repeated the same spells, only this time Parkinson managed to complete her disarming charm while Harry's stunning spell missed, losing him the duel.

"Professor Snape was right after all," she said smugly. Harry grimaced. Professor Snape had indeed been right—duelling was a mind game. If he could only repeat the same patterns, no matter how efficient they were, he would become predictable and therefore easily countered.

Sunday morning saw him in an empty classroom, sketching wand movements through the air to find convenient transition spells. The disarming charm was frustratingly irregular and did not fit well with anything else he knew besides the stunning spell. He remembered Professor Quirrell—or perhaps the Dark Lord—had mentioned that the Enemy's Curse was a good opening spell. It was four syllables and a much more straightforward wand movement to the disarming charm's five and awkward angle, so would probably be more difficult to disrupt. On the other hand, there were conjurations like serpensortia which both disrupted charms and constituted a physical threat, which could waste the opponent's time.

Harry thought about how the Dark Lord had duelled Dumbledore and the teachers in his body. He had alternated crucio and avada kedavra, with some unknown nonverbal spells sprinkled in between. Predictable didn't matter when you were deadly, he supposed. But the sheer mental precision required to cast vastly different spells in quick succession was mind-boggling to Harry. He could only switch from the disarming charm to the stunning spell and back twice before he risked a sloppy wand movement or insufficient focus.

Practice was what he needed.

Over the last three weeks of term, Harry focused on duelling with an almost single-minded obsession, neglecting even charms club. Penelope was on leave from extracurricular responsibilities and Gabriel was an all right leader, but the spells they learned there just didn't matter. Harry knew that, in the end, his burgeoning duelling skills did not matter either, but they were like straw thatching over the yawning pit of his dread, hiding it from view until he had almost convinced himself that there was a way across. His friends had no idea what had come over him, and he could find no words to explain himself, but at least Vince was happy enough to duel him repeatedly without asking too many questions.

Despite Harry's worries, or perhaps even because of them, time passed swiftly and he soon found himself packing his trunk in preparation for departure. The dementors hovering just beyond the morning mist over Hogsmeade station did nothing to help his nerves. This time, at least, they did not venture near the train.

When they reached King's Cross, Petri was thankfully there to meet him. Accompanying him was an unfamiliar man in rather threadbare robes that looked like they'd been mended ten times too many. He had an equally well-worn broomstick, of a model Harry did not recognise, tucked under his arm.

"Harry, this is Remus Lupin, a friend of Dumbledore's," Petri said without so much as a hello. "He'll be escorting us home."

Harry eyed the broomstick. "We're flying?"

Petri grimaced. "Flight is secure and difficult to trace, assuming the proper precautions are taken. Unfortunately, it seems that Dumbledore was unable to secure another ministry car."

"Albus has been quite busy lately," said Lupin. Harry had to agree—he hadn't seen Dumbledore at the head table for some time, even though he was sure the headmaster had remained at the school.

Petri ignored him entirely and gestured for Harry to come to his side. He bent down and whispered in his ear, almost inaudibly, "Ein Werwolf. Sei vorsichtig."

Harry eyed the apparent werewolf Lupin, but couldn't find any indication that he was anything more than a sleep-deprived wizard. What was he even supposed to be careful of?

They followed Lupin to the very end of the platform, past where the train ended, where Harry was shocked to see a thestral tied to a pillar. It stood there placidly, flicking its stringy tail now and then. As they approached, it snorted and shook itself, its reins jingling merrily. Lupin reached into his robe pocket and produced a chunk of raw meat, which he held out. In a flash, the thestral snapped up the treat, lowering its reptilian head and chewing noisily.

"It'd be best if Harry rode with me," Lupin said.

Petri cut him off. "Out of the question."

"The broom won't be very manoeuvrable with two riders. It's a poor defensive position," Lupin insisted.

Petri ground his teeth, apparently thinking furiously.

"You can't ride the thestral then?" Harry asked Petri. Lupin turned towards him, but then looked around in confusion, as if searching for something.

"Thestrals dislike me," Petri said. "Remus, how do you propose to protect Harry when you cannot even look at him?"

Lupin fixed his gaze back on Petri's sneering face and said, gently, "Perhaps you can tell me the secret, then? I admit, using the fidelius charm like this is an ingenious idea, but it makes things rather inconvenient."

"I don't trust you," Petri said bluntly.

Lupin looked away. "I suppose that's fair. We hardly know each other. But surely, you trust Albus—"

Petri laughed briefly, before his face grew stony. "The broom," he said, holding his hand out. "Harry will ride with me. You can take his luggage."

Lupin bit his lip but relented, passing the broom to Petri, who positioned it at waist height and swung his leg over the handle. Harry handed over his trunk before climbing on in front of him, yelping as Petri's wand struck his crown and something cold and slick slid down the back of his neck. The disillusionment charm. He tried waving his hand in front of his face, but there wasn't any distortion. He sighed. One day, his charmwork would be that good.

"Do you really think someone will try to attack me?" Harry asked.

"Somebody has already tried, or have you forgotten so quickly? The Dark Lord has ordered your death," Petri said.

"What?" Harry demanded. "How do you know that?"

"Dumbledore's spies."

"Dumbledore has spies?" Harry whispered in a high voice. He supposed he shouldn't be surprised.

Ahead of them, Lupin had mounted the thestral, which was unfurling its leathery wings. With one powerful sweep, it launched itself silently into the air and out of the train tunnel. Petri grunted and kicked off. They rose after its rapidly diminishing form, the broom shuddering and struggling to keep pace. Harry wondered uncharitably whether it would have been better if he had taken the handle.

They ascended almost vertically for several minutes until they broke through the clouds. Harry didn't think he had ever been this high up on a broom. Despite the speed and altitude, the charms on the broom kept them relatively warm and insulated from the wind.

"So how come Lupin's here with you?" Harry shouted.

"To navigate with the thestral, and as 'protection,'" Petri said in his ear with an audible sneer.

"Why didn't you just send Silviu again?"

Petri snorted. "In case it has escaped your notice, our landlord is colluding with the Dark Lord."

"So what?" said Harry, refusing to acknowledge the sting of anxiety in his chest. He had forgotten. "He doesn't know I'm Harry Potter. And he likes me."

Now he felt a twinge of guilt at the thought. How much of Silviu's fondness was real, and how much was because of what Harry had changed?

"That may be the case, but the Dark Lord himself knows who you are," Petri said. "You remember, don't you, that your possessed professor was able to recognise you?"

"Of course I do," Harry muttered.

Was this confirmation that Lord Voldemort was truly trying to kill him now? Or was this still the same sort of pretend, indirect attempted murder as before? Dumbledore had said not to play one's cards too early. But did that mean Harry should pretend that he didn't know that Voldemort wasn't trying to kill him, or pretend that he didn't even know that he was? Was Voldemort trying to lull him into a false sense of security? If so, it wasn't working at all, because he was terrified. He groaned as he felt his mind twisting into unlikely shapes.

They couldn't have been in the air longer than ten minutes before they started to descend. Harry supposed that the station wasn't that far from Diagon Alley. One moment, they were approaching a roiling mass of clouds from above, and the next they were looking down at a haphazard network of crooked buildings and winding roads that seemed to drop off into a blue abyss of sky. Harry almost twisted his neck as he looked up—there were the clouds, far above them—what had just happened?

"We're passing into expanded space," Petri explained. When Harry looked down again, the ground and other buildings had sprouted seamlessly into place at the edges of wizarding London. They skimmed over the black shingles of a row of Knockturn Alley rooftops before lighting down in the familiar grass of the graveyard.

Harry stumbled as he climbed off the broom, unused to his invisible legs. "Can you take off the charm now?" he asked.

"Not yet," said Petri. "Wait until we're inside. By the way, here."

Petri stuck his wand into his pocket and a slip of parchment shot out. He snatched it out of the air and held his hand out in Harry's approximate direction. Harry took it, trying not to roll his eyes at this excessive use of the summoning charm.

"Joachim Petris Sarg befindet sich in der Knockturngasse 66 / D-12," read the parchment in unfamiliar, blocky handwriting. As he read it, a sudden realisation bloomed almost tangibly in his head. He rubbed his temple as he looked up and found that they were standing right in front of their coffin plot.

"You put the fidelius charm on the coffin?" he demanded, but Petri wasn't paying him any mind.

Lupin had landed some metres away from them and was patting the thestral and feeding it more raw meat. Harry spotted his trunk at the man's feet. He made to go get it, but before he could, Petri raised his wand and summoned the trunk into his hand. He passed it to Harry with a muttered, "Go inside and you can cancel the disillusionment."

Harry slotted his circular house key into the coffin lid. It clicked open. He took one last glance back to where Petri and Lupin were now conversing inaudibly before reining in his curiosity and descending into their home.

His jaw dropped as he filled the jar at the bottom of the stairs with bluebell flames, illuminating the interior. The space had been totally transformed. It was bigger by at least a whole metre in every direction, and one of the long counters from inside the trunk seemed to have been moved into the main room, along with a pair of bookshelves. The centre slab of the kitchen table had been removed, leaving it circular and compact, and the beds were nowhere to be found. Ducking through the curtain into the bathroom, Harry discovered that it had been expanded into a much larger room, with the toilet separated from the beds by two heavy wooden screens.

Harry set his trunk down by his bed and rendered himself visible again before wandering back into the other room. He peered curiously at the mess on the counter. There were papers strewn about haphazardly, some of them on the floor, but instead of some glass contraption as Harry would have expected, there was wood of all sorts laid out, including what appeared to be a tree branch cut from one of the yew trees outside.

"What's all this?" he asked as Petri came down the stairs with an irritable look. His expression lightened as he glanced over.

"Oh, I've been experimenting with wand-making again," he said.

Harry remembered the fake wand Petri had made with the phoenix feather that Mrs Figg had given him, as well as the strange wand he had made for Rosenkol. "How does it work?" he asked.

"In the end, it's just a very complex enchantment," Petri said, depositing a handful of long, coarse hairs on the counter. Were those from the thestral? "I'm still working on the finer details, but I can create a crudely functioning wand for casting charms now. Are you interested in assisting me with testing?"

Harry was interested, but he wasn't about to just agree without knowing the details. "What would I have to do?"

"Cast a variety of spells and compare the performance to your own wand," Petri said.

"All right," Harry said. That sounded simple enough. "By the way, where did you get my wand?" Harry asked. "You didn't buy it for me, did you? Did it used to belong to somebody else?"

Petri nodded. "It used to be Horst's."

"Horst. Your second apprentice?" Harry asked. The one who had been kissed by a dementor. He stared down at his wand, which felt suddenly heavier.

"Yes," said Petri.

"Can you tell me about him?" The only one of his predecessors Harry really knew anything about was Ulrich, and that was only from their brief conversation during the one instance when he had been conjured with his personality intact.

"What do you wish to know?" Petri asked.

Harry thought about it for a moment, and said, "How did he become your apprentice? And how long—I mean, when did he die? What did he look like?"

"Imaginis," Petri said, conjuring a ghostly illusion with his wand. Harry blinked in surprise at the resulting apparition—tall and thin, with thick eyebrows and a curled goatee that did nothing to disguise his weak chin. For some reason, Harry had always imagined Horst as a teenager, but this was clearly a grown man.

"Horst and I met when he tried to rob my shop," Petri began, his lip curling, almost in fond reminiscence. "He was a typical lowlife, had left Durmstrang to work for a local ring of dark arts dealers. They knew to stay away from my shop, but I suppose they'd neglected to inform poor Horst. When he attempted to threaten me, naturally I enslaved him with the imperius curse right away."

Right, naturally, Harry thought.

"It turned out that he had hidden talent, however. He broke free of my curse after several months, and instead of running away, begged me to teach him the dark arts. As he'd already been assisting me with preparations, I accepted. Horst proved himself to be extremely capable… it's a great pity that he chose to die."

"Chose to die?" Harry repeated. "I thought he was kissed?"

"Yes. We often speak of the dementor's kiss as if it were the worst thing that could ever happen to somebody. Probably, it is. But when you spend a long time in the presence of dementors, a change overtakes you. Life seems dreadful, bland to the most terrible degree, and you become curious. You want to know what it's like to be dead. Not dead and gone, but dead and still whole, possessed of your mind but stripped of your will," Petri paused, blinking and running his fingers through his greying hair. "It's difficult to understand without first-hand experience, but that's what happened to Horst."

"There were dementors at school," Harry said suddenly. "I think I get what you mean by being curious. That's how they are, right? Extremely curious."

Petri's face twisted slowly into consternation. "Dementors at school," he finally said. "Why were there dementors at school?"

"They were guarding the school in case any of the Azkaban escapees showed up," Harry said.

"And who was guarding the students against them?" Petri demanded.

"Well they weren't literally in the school," Harry said hurriedly. "Just at the gates and in the forest. I… may have gone into the forest at one point and seen them."

"Seen them," Petri repeated dryly. "Did they try to communicate with you?"

"Communicate?" Harry asked, playing dumb. Petri saw right through him. He reached out, grabbed Harry by the shoulders, and pressed his face up to his temple.

"Communicate," he murmured, the stubble on his chin tickling Harry's nose.

"Yeah," Harry admitted. "Is that bad?"

Petri released him and sighed. There was an incredulous crinkle in the corner of his eye. "Since you're still alive, I assume it went well. You must have impressed them somehow."

"I suppose," Harry said, thinking of what the Dark Lord had done. He rubbed his arm.

"They will remember you now. First impressions are very important with dementors, so I hope you made it clear to them that they have more to gain from aiding you than eating you," Petri said. "Perhaps this is good. No doubt they'll flock to the Dark Lord's side as soon as he bothers to ask them. If they know you as another ally, it will be more difficult for him to convince them to turn on you."

"I only met a few of them, though," Harry said. Petri blinked at him in confusion for a moment before his lip quirked up in understanding.

"All dementors share the same knowledge. If you meet even one, you have met them all," he explained.

"Oh," Harry said. A concerning thought came to him. What if he hadn't made a good impression on the dementors after all? They didn't have eyes—when Lord Voldemort had possessed him, had the dementors simply sensed him instead of Harry? He didn't feel as if he could say all this to Petri, so he said instead, "Why is it important for them to like me? They're related to conjuration, right?"

"Yes. They are essential for sustained conjuration. They provide—what is the word—storage. By borrowing their magic, you can save a conjuration for later, so to speak, instead of being forced to start from the beginning each time."

Harry nodded. That seemed to agree with the archaic book on dementors and rising stones from the restricted section.

"Will you start teaching me conjuration?" Harry asked.

"Eager, aren't you? Very well. Show me your imaginis, cantato, and comprimo," Petri said.

Suddenly nervous, Harry wiped his palms on his robes and brandished his wand. He could do this. "Imaginis."

The image of Nearly-Headless Nick appeared, comically sized at Harry's height but with the original proportions. There was still an opaque cone of light revealing Harry's wand as the source, but the illusion was leaps and bounds ahead of his original attempts.

Petri nodded wordlessly.

Harry felt some relief at that. "Cantato," he said next. Furrowing his brows with concentration, he held the image of Nick steady and added in the movement of the mouth, the pompous but genial tone—"My name is Sir Nicholas de Mimsy Porpington."

Petri's eyebrows rose into his hairline and the corner of his lip twitched. "Fine," he said.

"Comprimo," Harry concluded. His eyes hurt from his unblinking exertion of will. Petri reached out and touched the illusion. His hand stopped at Nick's chest for a moment. Then he pressed harder, and his arm went through it.

Struck by sudden disappointment, Harry lost concentration and the whole thing dissolved into a beam of light with a bang. Petri flinched back, wand suddenly in hand, before he came to his senses and lowered it.

"Adequate," he concluded, and Harry let out the breath he had been holding. "You will not be needing comprimo for now, in any case. It is best to start with a surface."

Petri reached under the table and swung his trunk up on top of it. With two turns of the key he opened it up to the compartment full of glass objects and selected a simple hand mirror, which he passed to Harry.

"The aim of conjuration is first to retrieve the memory of a dead person, and second to convince it to operate as if it were still alive," Petri began, pulling up a chair and gesturing for Harry to sit down at the table. "To understand what exactly it is that we are doing, we will require a little bit of theory first. While we are alive and awake, every thought, every feeling we have leaves a magical imprint. These imprints are tied to us, inaccessible to others except by some specific, invasive means, until we die. When we die, those imprints are all still there, remembered by magic, and they can be accessed exactly as any form's properties are accessed for transfiguration. You have studied transfiguration forms at school?"

Harry nodded, screwing up his face as he tried to retrieve the definition. "Some. Something's form is like the ideal version of it that we imagine when we say its name."

"Ah yes, you have mentioned a key point—our imagination. Ordinary magic that captures a deceased person's image relies on the caster's imagination. Speaking portraits, for example, are painted while the artist interviews the sitter and so gets a proper impression of their personality. The other sort of conjuration is not like that. You need know only enough about the target to identify them. This is possible because we cheat, in a way. We capture the so-called soul, which is the singular form itself, and thus has all the knowledge that we lack," Petri said.

"A soul is a form? Dumbledore told me one time that the soul is our grasp of who we are. Does that mean the same thing?" Harry asked.

Petri sniffed, wrinkling his nose. "You could say that, yes, for the living. But who, exactly, will be grasping anything while dead? What about when asleep?"

Harry frowned. He supposed that was an obvious complication of that definition.

"I would say that the dead soul is more like a category. At any given time there are memories and thoughts which belong to it, and others which do not. Awareness is not required. Awareness can only be supplied by will, which belongs to the living," Petri said. "Anyway, for more practical purposes, whether or not the soul and form are the same thing, we are interested in the form, so that is what I will call it. Have you distinguished between deep and shallow transfiguration in lessons yet?"

Harry shook his head, dismayed, but Petri took it in stride.

"Perhaps that is an advanced topic. All you need to know is that a transfiguration is deep when no matter how you divide up the transfigured object, that is, how deeply you cut, no trace of the original object remains. A deep transfiguration is a perfect instantiation of a form. Do you understand?"

"Yes, that makes sense," Harry said. The only time he had thought much about what the inside of a transfiguration looked like was that one afternoon in the Hogwarts kitchens, when Nelly had shown him the elves' food transfiguration. It hadn't occurred to him that some apparently successful transfigurations, perhaps even most of his own, did not completely permeate an object.

Petri continued, "Here is where we cheat. Obviously, if we could do a deep conjuration, that would be equivalent to retrieving the entire form. But it is effectively impossible to conjure any human out of thin air, let alone a fully-functional one. What we can instead do is conjure a derivative concept—the ghost of a person, or their reflection."

He gestured to the hand mirror.

"You see, a person's reflection cannot be said to exist as an object. It simply results from that person interacting with a mirror. If we want to conjure a perfect reflection in the glass, one that can behave exactly like the real thing, then we must have something to reflect, yes? So even though we have only done enough magic to produce an image in a mirror, we in fact have the entire form in our hands, with no need to produce blood, flesh, and bone."

"That's it?" Harry could not help asking. Conjuring an image in a mirror—that hardly seemed nefarious. "And this is dark magic?"

Petri blinked. "Of course it's not dark magic," he said, laughing. "It hurts no one. It is preserving the conjuration that is dark. The reflection method as it is does not produce anything more useful than an enchanted portrait. You will usually want to bring back the dead more literally, and for this you will need a functional human body. Unless you are suicidal, this requires some… volunteer to offer. Preferably two others so that they do not die as quickly."

"Why would they die?" Harry asked. "It didn't hurt me when you conjured Ulrich with my blood, did it?"

"Ulrich is a special case—normally you will not conveniently have the reanimated original body available, so the conjuration will effectively be possessing someone. Having been a victim of possession yourself, surely it is clear to you why this is bad for one's health?" said Petri.

Harry blinked. "Actually, could you still explain it? Dumbledore said that having the wrong soul in a body strains it somehow, but I didn't completely understand how. And when the Dark Lord possessed me I honestly don't think there were any side effects."

Petri furrowed his brow. "After several weeks of possession you should have been suffering from anaemia at the very least. Nothing can be ordinary with you, can it?"

"I didn't ask for it. I wish I could just be normal," Harry muttered.

"You do not," said Petri. "If you were normal, you would have died as a baby."

Harry supposed he couldn't contradict that.

"For a normal person, the body and its form are always acting upon each other. Changes to the body, if not soon reversed, become part of the form, and changes to the form become reflected on the body. During a possession, two forms are exerting themselves on the body, with the foreign spirit constantly attempting to enact a transfiguration and the original owner resisting it. Sometimes this leads to a partial transfiguration or to gruesome transmogrifications, such as additional body parts appearing in unlikely locations. Even if nothing so dramatic occurs, so much magic acting on the body constantly will cause parts of it to die, starting with the blood," Petri explained. "I cannot imagine why this did not happen with you and the Dark Lord. Perhaps he has developed some way of restraining the effect of his form."

This couldn't be true, Harry thought, because Professor Quirrell had been affected quite badly by the Dark Lord's possession, exactly as Petri had described.

Still, he said, "Maybe. Okay. So possession is bad for you. But it's fine to just conjure someone and then let them go after… how long? A few minutes? Hours?"

"Under an hour should be safe," Petri said. "However, a successful conjuration may take you days or even weeks to prepare, so such a short time generally seems inadequate. If you have spare bodies ready, you might hold the conjuration for weeks or months. Alternatively, you can use a dementor's magic to preserve the form and conjure it when needed with no further preparation. To begin with, you will be practising on Ulrich to gain a good understanding of the spell. I believe the experience will help you later when you attempt a full conjuration from start to finish."

Petri paused, as if remembering something. "Do you still have that headless ghost that you wrote me about?"

Harry nodded, wondering at the random question. "He's in my trunk."

"Good. It will be invaluable for helping you link a conjuration to a body," Petri said.

"How?" Harry asked.

"There is an enormous amount of information stored inside a ghost about how a body should behave, things you would normally be forced to spell manually using erudito, as a conjuration rarely includes that information naturally. With a headless ghost, you can conveniently omit the head so that your conjuration's identity doesn't get confused. There's an added advantage of extra resentment," Petri paused. "Have I taught you about resentment?"

"Maybe a little," Harry hedged, knowing full well that Petri hadn't. "It's related to how strong a ghost is?"

Petri shrugged. "It's literally what you'd expect from resentment—lingering indignation at having been wronged. Magic fueled by resentment is especially suitable for going against the natural order of things, such as restoring the dead."

"But if you use the ghost's resentment up, it'll disappear?" Harry asked.

"Yes, unfortunately. One use only," Petri confirmed with a regretful look. That wasn't exactly what Harry had been concerned about, but he supposed it answered his question. He bit his lip. Ghosts weren't conscious—Dumbledore had told him that, so it was all right, wasn't it? He wished he had checked out the book that the headmaster had recommended. With all the extracurricular duelling occupying him, the matter had slipped his mind.

Petri set the trunk on the floor and turned the key twice in the lock, opening it again to reveal a drop into a familiar chamber. Harry followed him down into the workshop, where Petri took a grey pebble from a drawer and held it gingerly between two fingers.

"This is the resurrection stone to which I have bound Ulrich's form. Take it in your left hand," Petri instructed. Harry held out his hand. "Turn the stone over at the same time as you cast the spell, once per repetition. The mantra is spiritus revocatur, or simply spiritus if you prefer a faster repetition, and the wand movement is a trefoil knot."

"Sorry, a what?" Harry interrupted, blinking at the unfamiliar term.

Petri demonstrated briefly. At a casual glance, it almost looked like an ordinary circular motion, but there was a slant to his wrist and Harry could see after a few repetitions that the wand tip reached three distinct extremes. He bit his lip as he tried to copy the movement clumsily. It was unlike any spell he had attempted before.

"As you traverse each loop, consider the mind, body, and identity of the one you are conjuring. The stone holds the form, but you must still do the work to draw it out," Petri said. He helpfully propped the mirror up on the table.

Clearing his throat, Harry held up the stone and his wand and began.

"Spiritus revocatur… spiritus recovatur," he murmured, beginning slowly as he tried to keep his wand movement in the proper conformation. He could feel himself reddening as he realised he had forgotten to turn the stone. At that very moment, he thought he could fully sympathise with Vince's struggle to do two things at once.

It took some time to get used to the motions, but by the time his mouth ran dry he felt he had ingrained them into his muscle memory. The problem was that the shimmering image of Ulrich that would form in the glass was just that—an image. Ulrich's reflection was not the same concept as the image of Ulrich's face in the glass. Harry knew that intellectually, but found it impossible to understand what physical difference there could be. The true Ulrich remained frustratingly out of reach.

"I do not expect you to make substantial progress in just these few weeks, let alone one evening," Petri told him after he returned to find Harry still struggling at the task. Harry didn't know for sure how much time had passed, but by the ache in his eye sockets and the stiffness in his knees he wagered it must be deep into the night.

He wedged his thumb underneath his glasses to rub at the corner of his eye, sighing. "I feel like I know what I should be doing, but I just can't do it," he muttered. "You're sure I can do it, right? It doesn't take a lot of magic?"

Petri gestured to the mirror. "You have seen for yourself that you can handle enough magic to conjure the image. It is simply a difficult spell because of its precise requirements. I doubt you have had to cast any other spell before where metaphysical identity matters."

Harry frowned as he suddenly remembered something random—Patil, summoning Luna's shoes without ever having seen them. "The summoning charm," he said. "Sorry. I just thought maybe identity matters for it too."

"It does," Petri agreed. "But it isn't exactly difficult to conceptualise the identity of something you can see."

As if to demonstrate, he summoned the hand mirror from the table. It slowed as it approached, falling easily into Petri's outstretched hand.

"But you can summon things you've never seen before," Harry said. "Sixth-series summoning. I saw somebody do it."

Petri's lip curled. "One can, yes. Can you?"

Harry frowned. "Should I practise the summoning charm, then? Do you think it would be easier?"

Petri laughed. "You are welcome to begin the summoning series, but it would be a very roundabout way of learning conjuration, if it helps at all. Practice is the most direct route, and likely the best use of our limited time. But rest is also important. You can continue trying tomorrow."

Harry grunted and held out the stone, which Petri took and put back in its place.

"I don't remember you using the stone last time," Harry said.

"It isn't strictly necessary to hold it," Petri explained. "Proximity is enough, but the closer you are the, easier it is."

"Can you conjure Ulrich again, to show me? Maybe the problem is that I don't know him that well. I've only talked to him the once," Harry said.

Petri hummed. "Perhaps. Tomorrow."

This was when Harry discovered that it was nearly three in the morning, and that by 'tomorrow,' Petri was referring to the next evening. Resolving to get back to a nocturnal schedule in one go, Harry forced himself to stay up, though he accepted that he was in no mental shape to be doing any more spell practice.

"I'm going to get some air," Harry said as they climbed out of the trunk. He grabbed his cloak. After months in the draughty halls of Hogwarts, the windowless coffin felt horribly stuffy.

"Don't leave the graveyard," Petri said.

"Right. Wasn't planning to," Harry muttered, a little annoyed. He seriously doubted that it mattered where he went—unless he stayed shut up in the fidelius-charmed coffin, the Dark Lord or Death Eaters could just as easily kidnap him from inside the graveyard as outside of it.

"Hey, Harry!" someone called out the moment he popped outside, startling him badly. He tripped over the edge of the coffin and landed on his face. His glasses stabbed into the bridge of his nose.

"Ouch, kid, you all right? Sorry if I scared you," glowing green eyes blinked out of the darkness as Harry looked up, his nose throbbing. It was Shy. He almost relaxed, and then remembered Petri's concerns about Silviu working with the Dark Lord.

Forget that. For all Harry knew, he himself was still working with the Dark Lord. He pulled himself to his feet using the nearest headstone and dusted himself off, though he palmed his wand, just in case.

"Oh, hello Shy. I'm fine," he murmured, floundering for something to say. Finally, he settled on, "What are you doing out here?"

Shy's eyes slimmed to pleased crescents. "Gardening! Sanguini gave me a cutting from his venomous tentacula. You know Sanguini, right, from B Thirteen?" She pointed off to the left, where Harry could barely make out the hulking figure of an enormous, spiky plant. Then Shy pointed to her own plot, where a clay pot with a single wiggling tentacle sat askew atop a mound of dirt.

"I haven't met him, sorry. I don't get out much. That's a carnivorous plant, right?" Harry said, eyeing the tentacula.

Shy nodded. "It's sort of like a snake. Or a bunch of snakes, really. It swallows prey whole, it's got venomous fangs, and it's cute. Also, the venom of a mature tentacula is supposed to be super potent—it's a magical toxin. They apparently use it in dragon tranquilisers. I'm hoping to make some for my shop."

Harry nodded, eyeing the plant a little nervously. It seemed like the sort of terror that belonged in Greenhouse Three at Hogwarts. "That makes sense. I've been wondering—don't take this the wrong way, but how come you have a poison shop? I mean, isn't it sort of… dubious for someone to buy poison?"

Shy laughed. "Don't worry. I thought it was mad at first too—corner shop where you can just pick up cobra venom? It turns out magical folks are pretty hard to kill with regular poisons. Only magical poisons, like in these tentacula, will do anything to you lot, and even then you've got a fair chance. The poisons I sell are mostly supposed to be ingredients in potions, which I assume end up non-poisonous…" She scratched her head. "You can probably make stronger poisons out of them to murder people with, too, but it's not my problem if my customers get arrested. Well actually, it is, because then they wouldn't come back, but you know, at least I don't get arrested too."

Harry couldn't help quirking his lip at this. "Yeah, I hear Azkaban's chilly this time of year."

"Ha! That it is. But enough about me. What about you? You back from school for Christmas?" Shy asked.

Harry nodded. "Just got home earlier today."

"And how long will you be around for?" Shy asked.

"Two weeks," Harry said. "Term starts up again on the fourth, I think."

Shy grinned, accidentally flashing her fangs. "Great, that's plenty of time. You've got to come around my shop again to see my new king cobra. He's massive and he's got these really pretty gold chevrons. I've named him Harry, after you. Sorry if that's strange."

"I'm… flattered, I suppose," Harry said, a little taken aback. Did Shy really know him well enough to be naming a snake after him? They were really just casually acquainted neighbours, weren't they? Then again, Harry thought guiltily, they were also supposed to be the vampire equivalent of siblings.

There was also no way he was going to convince Petri to let him go to Shy's shop, which was literally full of poison, whatever assurances she had just given about its legality. He frowned. She hadn't made any explicit invitation yet. Perhaps he would simply deflect until the time came for him to return to Hogwarts.

"You don't know how much you changed my life, Harry," Shy was telling him, still grinning. "Snake language is just brilliant. They really listen to it! If they're not eating, I can just tell them 'food,' and bam, suddenly they go for a rat they've been ignoring for ages. I need you to teach me another one, I mean, if you're up for it. How do you say, 'get in the bin?'"

Harry blinked. "Get in the bin?" he repeated, in English.

"Yeah, so I can give them their baths. Some of them like the water but the others try to pop out as soon as I drop them in. It's annoying," Shy explained.

So Harry licked his lips, imagined a snake, and said the phrase.

Shy repeated after him. "Inside the hole," she seemed to say. Harry blinked.

"Close enough," he told her. What she had said before sparked his curiosity. "Are you saying that snakes always do what you say, when you talk to them in Parseltongue?"

Shy screwed up her face in thought, before nodding. "Yeah, I reckon that's right. It works every time."

Glancing around, though he wasn't sure what he was checking for, Harry took out his wand and muttered, "Serpensortia!" There was a bang and something flopped onto the dirt.

Shy leapt back. "Oi! Did you just magic up a snake?"

Harry was busy straining his eyes in search of his wayward conjuration, which had slithered off to parts unknown. "Come back, snake," he said, hoping it was Parseltongue that had come out. There was a susurration in the icy, brittle grass and a tiny black head popped to attention.

"Sorry, should have warned you," Harry said to Shy.

"What sort of snake is it?" she asked, bending down and reaching out. In an expert manoeuvre she hooked it with a finger and had it writhing around both hands in a moment. "I don't recognise it. Looks sort of like a grass snake except it hasn't got any yellow on its neck."

"Probably not a real kind of snake," Harry said, scratching his head and thinking about what form he had been considering. "I suppose it's some generic snake."

Shy blinked at him. "A generic snake," she repeated, lifting the snake up to peer at its underside. It wound curiously about her fingers. "Seems pretty real to me."

"It won't last too long, I don't think," Harry warned her. "It'll vanish after a while. I just wanted to test what you said."

He held out his hand and asked for the snake to come to him. It slithered easily from Shy to him. He frowned. "I don't know if it works because of Parseltongue, or because I conjured it."

"You can try on my real snakes later," Shy said.

With a sucking sound and a faint puff of smoke, the conjured snake disappeared. Harry shrugged and pocketed his wand.

"What other things do you learn at magic school?" Shy asked. "Can you turn people into toads?"

"I think that's rather advanced," Harry said.

"But it's possible?" Shy pressed.

Harry nodded. "I think so."

"Blimey, I really better not get on the wrong side of a wizard." Shy leaned forward and put her hand up to the side of her face, stage whispering, "Don't tell him I said this, but it's a good thing the chairman isn't all that good with that wand of his."

"He isn't?" Harry asked, unconvinced. He'd seen Silviu manage some pretty advanced magic.

"All he can do is make tablecloths and wipe memories," Shy said, rolling her eyes. "Seems like a waste of effort to use wizard magic for that when you can do the same thing with your eyes. Not the tablecloths, I suppose, but honestly that doesn't seem that useful."

"How does your eye magic work?" Harry asked.

"You just look really hard, like you're trying to see through someone," Shy said. "Want to try it out?"

Harry grunted in the back of his throat, unwilling to consent outright. On the one hand, it seemed dangerous. On the other hand, legilimency seemed very useful.

"Since we're company, we should be able to connect both ways even though you're still human. Maybe it'll work better if I give you some blood first," Shy said, and before Harry could voice protest, bit herself on her forearm.

The scent struck him instantly, as if blown by a gust of wind, though the night was still. A sweet haze clung to his palate. His mouth watered. Shy stuck out her arm. Harry stared up at her, dumbfounded.

"What, never licked a girl before?" she asked, waggling her eyebrows. Harry blushed from head to toe. "Come on, before it gets cold."

He'd never licked anybody, because that was gross. Despite this thought, he didn't feel disgusted, only vaguely thirsty. He leaned forward and swiped his tongue over Shy's bronze skin, darkened with blood. The now familiar taste of iron and salt, tinged with treacle-like sweetness, sent a shiver of alertness through his body. He tore himself away before he could overstay his welcome, and Shy casually wrapped her hand around the wound.

He met her eyes. A bright ring of red had blossomed around her slit pupils, terribly reminiscent of the Dark Lord.

"Focus on me," Shy said, her voice suddenly crisper. "We'll play a game. What number am I thinking of?"

Harry furrowed his brow, staring at her. Like he was trying to look through her, she had said. A number? A number instantly flashed into his mind, and he dutifully repeated it, though he was doubtful. "Seven hundred forty-eight?"

"Nice one," she said, to his surprise. "Your turn."

"I just think of a number?" he asked. She nodded. Harry finally settled on the number two. Then, feeling a little mischievous, tried his best to occlude.

Shy's eyes burned a brighter red. "What gives? Are you even thinking of anything?"

"Sorry," Harry said a little guiltily. "I wanted to see if I could keep you out."

"Well, I suppose I could use a challenge," she said, grinning viciously. Harry felt suddenly lightheaded. "Two!" Shy declared.

"That's right," Harry said, shaking his head to clear out the feeling of cobwebs in his head.

They played a few rounds more, until Harry found he couldn't get anything.

"Are you occluding now?" he asked.

Shy blinked. "Am I what?"

"Trying to stop me?" Harry clarified. Shy shook her head.

"I reckon my blood's worn off," she said. "You didn't take much, and it costs blood to use our powers. Other people's blood, I mean. Obviously you've got your own but I don't think you can use it like that."

"Oh," Harry said, a little disappointed that this wasn't quite the shortcut to learning legilimency that he had hoped for. "Thanks for showing me."

"Sure. It was fun. Want to help me with this tentacula?" Shy asked, turning back to her forgotten gardening. Harry eyed the flailing tentacle, which was already equipped with a pair of inch-long fangs.

"I'm really not that great at herbology," he said quickly. "And I better go back inside. Homework."

Shy laughed, but did not try to keep him as he retreated into the coffin house.

Petri was busy chiselling wood in the back of the room seated on a high stool. He glanced up as Harry entered and threw a wand at him, which Harry caught reflexively before it could stab him in the neck.

"Try casting the levitation charm with that," Petri said.

Harry pointed the experimental wand a piece of parchment on the table. "Wingardium leviosa." Swish and flick. The paper flew into the air, as if blown by a strong breeze, and flopped over, drifting to the ground.

"So it's the same for you. It isn't holding onto the right shape," Petri muttered. He held out his hand, and Harry walked over to return the wand. Petri took it, setting it aside and trading it for his actual wand. He checked the time, wiping his eyes with the edge of his sleeve. "Did you enjoy your walk? You were out for quite some time."

"I was talking to one of our neighbours," Harry said. "I've been wondering—why are vampires' eyes red? And the Dark Lord's eyes too?"

Petri pointed his wand off to the side and narrowed his eyes. The tip glowed red. "Magic in small amounts is invisible to us. Concentrate more magic in a small area, and it will begin to glow red. Yet more, and it brightens to white."

The light at the tip of Petri's wand bled into sunny yellow, before paling to a fluorescent white. As he held it for even longer, the light began to turn distinctly blue. At this point, he discharged it, the bright beam of the Enemy's Curse flashing across the room and dissipating against the wall to no effect.

"The red eye effect is a result of relatively powerful magic being cast from the eyes. For vampires, it is an expression of the vampire's curse. As for the Dark Lord, he must constantly be maintaining some sort of ocular spell. Perhaps it is simply to enhance his vision, or perhaps there is some more sinister purpose," Petri said.

"There are spells to make you see better, then?" Harry asked. Petri glanced at him critically.

"There are all manner of charms to help one see the unseen. If you are interested in ordinary vision correction, I believe there is a way to transfigure your eyes into a more ideal shape. Of course, as with all human transfiguration, there is a risk of it going very wrong, which would probably render you blind. Are my spectacular spectacles not to your satisfaction?" he asked.

"No—I mean, yes, they're really great," Harry said hastily, grasping the frames of his glasses with both hands, as if Petri might snatch them off his face. "They've helped me out a lot. I was just wondering, that's all."

Petri grunted. "Have you been spying on people with them, then?"

"No!" Harry denied. "Well, not without good cause. You heard about a Hogwarts student committing suicide, right?"

"It was in the paper, yes," Petri said, tilting his head in curiosity.

Harry quickly told him about the cursed book they had uncovered, and how it had been influencing Penelope.

Petri had worn a light frown all through the story. "I've never heard about a curse that can cause depression," he said. "Genuine emotions are notoriously difficult to create with magic. Was it perhaps something like a dementor's aura?"

Harry shook his head. "It seemed like a totally ordinary book to me. I think you must have had to write in it for it to curse you."

"What was the title of the book? Do you know?" Petri asked.

Harry frowned, trying to recall it. To his surprise, the image of the title page jumped suddenly into his head with crystal clarity. "It was called Bridging the Veil."

Petri nearly pitched off his stool. "Bridging the Veil?"

"You've heard of it?" Harry asked, blinking in surprise.

"It's a necromancer's artefact. Supposedly it can reliably induce prophetic trances," Petri explained, sounding bewildered. "I don't see how it could induce depression."

"Perhaps it's a different book with the same name?" Harry speculated, equally confused.

"Perhaps," Petri muttered, clearly unconvinced. "You said that Dumbledore confiscated the book? I'll ask him if I can take a look at it."

Harry shrugged, thinking it unlikely that Dumbledore would be daft enough to just let Petri borrow a dark artefact. He pulled up a chair at the table and sat down, bringing both his hands up to cover a yawn.

Seeing this, Petri said, "You may consider going to bed."

"I'm trying to go nocturnal again," Harry protested, swallowing another yawn.

"Perhaps that isn't such a good idea. You'll be returning to school in a matter of weeks," Petri pointed out.

"But if I sleep at night, what would I do all day?" Harry asked.

"Practise conjuration. Read. Write the homework that I'm sure you have been assigned," Petri suggested. Harry wrinkled his nose.

"I don't want to stay inside the whole time. I need to do some Christmas shopping still," he said, pasting a hopeful look on his face. "Can I go to Carkitt tomorrow?"

"Dumbledore's pet werewolf can take you," Petri said, to Harry's surprise, as he had expected to be shot down. "He has been tasked with your protection." A disdainful eye-roll told Harry what Petri thought of that.

"Protection against the Dark Lord?" Harry asked, just to be sure.

"Against his followers," Petri corrected. "Dumbledore has informed me that the Dark Lord does not appear to be personally targeting you. Based on this information and what we know of your fate, I think it is unlikely that you will be at risk of death, but that does not mean that you cannot be maimed."

Harry grimaced at this unwelcome but valid point. He had been so focused on the possibility of dying that other, perhaps worse scenarios had not even occurred to him.

"Be wary of the werewolf as well," Petri added. "He does seem uncommonly tame, but remember that under the civilised facade is a beast with a predilection for human flesh."

"But he's supposed to be my protection?" Harry asked. "Seems a little like a double-edged sword."

"I am told he was friends with your parents," Petri said.

Harry perked up at this. He still knew precious little about his parents, something which most certainly needed to change if he was to have any hope of bringing them back. His earlier attempts with Ulrich had shown him that a mere passing familiarity would likely be insufficient.

"And he'll be awake during the day?" Harry asked. Petri nodded, writing down an address for him. It was for a flat in one of the neighbouring alleys that turned off from Knockturn. "This isn't another fidelius charm, is it?" Harry muttered suspiciously.

"No, no fidelius," Petri said, eyes crinkling in amusement. "But I recommend you call him by floo so that he can come to retrieve you. Dumbledore does not want you to leave the graveyard unaccompanied."

"How do I call instead of just going through?" Harry asked.

Petri looked a little surprised at this question, but answered anyway: "What you need to do is use half the regular amount of floo powder. When the fire turns green, say the address and put only your head in the fire."

"Right, okay," Harry said, blinking.

"I'll write it down," Petri said, scribbling an addendum on the parchment. He made a shooing motion with his other hand. "Go to bed. You look like you can hardly sit up straight."

Petri was right. Harry swayed slightly as he got to his feet, blinking with aching eyes. For a moment, he stared into the corner of the room where his bed used to be in blank incomprehension. It had been a long day. Recalling the new layout, he dragged himself into the next room.