Author's note: The next two chapters were originally written as one, but it got so long thatI split it. I'll try and load them together. I have taken huge liberties here with wand technicalities. I've followed canon in so far as it goes… but then gone much further. My feeling is that if a wand tree is not specified in canon, that does not mean it cannot be used, just that JKR has not yet made reference to it. i.e. Anything goes!

...It is the early hours of Thursday morning, and, as Snape was asleep, drugged by the Shark-Lily, Hermione and Neville have decided to try out the theory on Harry…

DECK THE HALLS

By Bellegeste

CHAPTER 6 : NEVILLE'S THEORY

Thursday 19th December

"I don't get it. What's James Potter's wand got to do with Professor McGonagall?" moaned Harry blearily. He hugged his dressing gown round him more tightly and stared at them dull-eyed, blinking blindly for consciousness through a fog of interrupted sleep. He was not at all happy about being woken up at five-thirty in the morning, especially by Neville prodding his stomach and making spitty 'psst!' noises in his ear. Following Neville downstairs to the Common Room, he had been surprised to find Hermione, fully dressed, perched in one of the squashy armchairs, wide-awake and holding a clipboard - like a market researcher conducting a consumer survey. Both she and Neville looked tired, as though they hadn't had much sleep either, but there was a fervour about them, some kind of suppressed excitement that told Harry they were onto something big.

"Neville's got an idea - about what's happening to our magic. We haven't much empirical evidence as yet, to support the hypothesis, but we've been running tests in the Greenhouse all night and all the results point towards the same conclusion. We need more hard data now to corroborate the theory. So, we're compiling a list…" Hermione spoke with her 'pre-exam' intensity, focussed and keen.

"Whoa! Slow down! WHAT theory?" Harry demanded, struggling now to wake up and keep up. Hermione gave Neville an 'over to you' nod. This was his moment. Harry could see him puffing slightly, modesty barely containing the swell of self-importance; he looked like Trevor, inflated and about to croak.

"It's a fungicidal, devolutionary, pathogenic, viral contaminant!" he announced. "I think. Well, it might be. It's possible. I can't prove it yet but…"

"Oh, God!" groaned Harry, wishing he were still in bed. "What the heck's one of those? How can something be a virus and a fungus?"

"At a cellular level - " Neville began ponderously, but Hermione cut him off.

"Don't get too technical on us, Neville. Harry still gets styles and stigma muddled up. Anyway, don't listen to him, Harry - we've got as much proof as we need. I'm convinced anyhow. But we've had to make a lot of assumptions. That's why we had to wake you up; there are certain details which might - "

"Hey! I still don't get this. You're going to have to run it past me again. Slowly. In layman's terms. In words of less than four syllables." Harry was awake now, but totally bemused. Hermione rolled her eyes in impatience and sat twisting her frizz of hair into thick, springy corkscrews, as Neville began at the beginning.

"I've been giving the matter a great deal of thought, a great deal," he said in his flat, Lancashire accent, "and the con-clusion I've come to is that I did everything right. I mean, I always thought I did, but I couldn't be positive; and everyone seemed to think that I didn't. But I did. I was that careful!"

Harry was sure that he had been. But he hadn't a clue what he was talking about. Neville saw the incomprehension glazing his eyes; it was a feeling he recognised only too well.

"In my brewing, Harry. In my Potions. Why should they have gone so wrong? So, it follows that, if I followed the instructions right - and I swear that I did - then it must have been my ingredients that were wrong. They'd been tampered with. That's the only explanation I can come up with for what happened on Monday, and why I poisoned Professor Snape yesterday…"

"What!?" No one had thought to tell Harry. "What've you done to him, Longbottom?" he demanded to know. He wasn't feeling too sympathetic towards his father - the man couldn't even be bothered to visit him to find out if his hand was better - but that didn't mean he wanted him poisoned. Hermione hurried to reassure him.

"Snape's fine, Harry. Or he will be, by this morning. It was an accident."

Neville made an apologetic face.

"Somebody - mentioning no names, mind, but I've got a good idea who - substituted un-blanched Shark-Lily to put in my Calming Draught . Though why he's got it in for me, I don't know. I suppose he thinks it's funny."

Behind Neville's back Hermione silently mouthed the name 'Malfoy'.

"Anyway, to get back to Monday… You know my project? The one I'm doing for Professor Sprout?"

"The sick plant survey?" Harry wished Neville hadn't started quite so far back. Were they going to re-enact the whole of the last week?

"Very droll, Harry," he said, a note of reproach in his voice. "Part of the project is going to involve trials – blind and double-blind trials – of various plant pathogens. There were samples in Professor Sprout's shed, waiting to be tested and analysed. I didn't know what half of them were - obviously, otherwise I might have prejudiced the results of the study…"

"Obviously!"

"And I'm guessing that the same somebody, also substituted one of those samples for one of my ingredients for Monday's potion. We haven't isolated the contaminant yet, but we're narrowing it down. There are so many bally things it could be: canker, smut, wilt, thrips, scab, spraing, blotch, gummosis, chafer grubs, botrytis, blight…" He was counting them off on his fingers, and looked as though he could list several more hands' worth…

By this point Hermione was almost beside herself in her eagerness to explain to Harry how the pieces of the jigsaw fitted into place.

"And so Draco Hot-Hexed Neville's wand," she declared, "and he dropped it in the potion with the fungus in it, and the wand got contaminated…"

"Sounds a bit far-fetched to me," muttered Harry.

"No, listen, Harry. There's more, and it all starts to make a horrible kind of sense," said Hermione, more seriously. "The only person who knew what was in those samples was Professor Sprout. And she's disappeared, right? And who is the only person who knows how to kill the 'germs', or whatever they are, in those samples?"

"Professor Sprout?" Harry replied on cue.

"Precisely!"

"OK," Harry argued, "so Neville's wand gets dipped in some mouldy potion. So what? What's that got to do with our magic going up the creek? It doesn't explain why the school's under some weird Jinx, and everybody's powers are totally fucked. It doesn't explain why Ron can't stop crying and Ginny's grown spikes… It doesn't explain why my wand burned to bits in my pocket!"

Harry wanted to believe them, but all their evidence so far had been circumstantial. He hadn't intended to sound so sceptical, but he needed more proof. This had all been sprung on him; he needed time to assimilate it. He was feeling unaccountably upset – if anyone had asked he would have said he was tired and hungry, but he suspected it had more to do with the way his stomach had dipped in alarm when Neville was talking about Snape… He didn't want to care, but he couldn't help it.

"No, we don't have all the answers," said Neville patiently. "We know my wand got contaminated in my cauldron on Monday, and we think that other wands have been infected, but we don't know how the virus or bacteria are spreading…"

"Airborne," piped up Hermione, "definitely. If it were merely contagious it wouldn't have spread nearly so quickly - it's not as though we get much wand to wand contact. We don't fence with the wretched things. Or, most of us don't," she said in a superior tone, thinking despairingly of Ron.

"Ah, but we do touch them," pointed out Neville. "And then there'd be hand to hand contact, door-handles, taps - all sorts of places where a virus could be transferred. And we haven't discounted the possibility of spores – either free-floating, or carried on our clothes or hair…"

Hermione stopped twiddling her hair and glanced nervously down at her empty hand…

"Or we could be carriers," went on Neville gloomily. "We could all have inhaled the 'germs', pathogens - whatever you want to call them - and be breathing them out all round the castle…"

"Great! So our wands have got some bug," said Harry, trying to get back into the conversation, which seemed to be degenerating into a two-way debate on the spread of infection. "What do we do about it? Wash them? Dip them in disinfectant? Put them to bed with a warm drink? What?"

"We're not talking about a common or garden dose of Chizpurfles here, you know, Harry," said Hermione gravely. Neville shook his head.

They were both regarding him with the scornful, humouring pity normally reserved for Ron and his space quotations.

"Think it through, Harry," murmured Hermione.

"Don't bloody patronise me!" he snapped, wondering what he'd missed that was so important.

"What day is it today?" she prompted.

"Thursday. Why?"

"And tomorrow is?"

"Duh! Friday. So?"

"Yes, Friday. The last day of term. Tomorrow everybody is going home for the Christmas holidays. Just imagine what this 'bug' will do if it gets out into the wider wizarding community…"

"Oh, shit," said Harry, imagining only too vividly.

x x x

In the Slytherin dormitory, Draco Malfoy slept the satisfied, untroubled sleep of the accomplished saboteur. A watery yellow light bruised the darkness as dawn approached, and a shaft of pale gold crowned the blond head, sunk into soft pillows in carefree slumber. He twitched once, ducking down as a flight of seabirds swept across his cloudless dreams, heading south to more temperate minds, escaping the malice of winter, and he smiled at their passing. Then he rolled over, enfolding himself in the glorious mantle of success - this time he had excelled himself - and it was a cosy, guilt-free, warm and fuzzy feeling.

Because, to be honest, he'd hadn't a fuckin' clue what crap it was he'd mixed in with Longbottom's crushed Bladder-wrack. It was just some slimy stuff he'd found in a pot on Sprout's shelf. He hadn't even read the label. Actually, now he thought about it, he wasn't sure it had even had a label. He'd spotted the row of gruesome, green jars when he nipped in to pinch the sample of fresh Shark-Lily, and it had seemed a sweet idea at the time. Good idea? Absolutely, outstandingly, Champagne-bubblingly brilliant idea, more like! It was all his vilest fantasies come true! The whole school was falling apart, the staff were at their wits' end, Hogwarts was magically helpless and he, Draco Malfoy, could take the credit, thank you very much. Thank you, thank you. He awarded himself a jewel encrusted 'Salazar's Snake' and took a gracious bow to the crowds of cheering fans…

If that blabber-mouthed herb-head, Dungbottom, hadn't been blathering on about his precious bulbs and roots, Draco would never have got the idea in the first place. But the Shark-Lily had potential - he'd recognised that from the very start. All he'd have to do was to engineer some reason for Snape to be observing Longbottom's cauldron at the crucial moment. And he hadn't even had to do that! They'd more or less done it themselves! Surely it was fate? Get past the wards into Severus Snape's inner sanctum? Impossible? No problem! Not for Draco Malfoy!

And the slime stuff on Monday? Draco almost groaned out loud with pleasure at the memory. It was too good to be true. All he'd intended to do was make that fat gimp screw up his potion; it always made for excellent entertainment to get Snape screaming at the Gryffindors; and besides, Longbottom virtually had a sign on his Dunce's cap saying 'Piss-takers welcome'. Yeah, he had Hexed the wand, as a bit of an added bonus - how was he to know that twit would drop it into the cauldron? And then go fishing for it? Oh, priceless! Bravo! Spot-on, Malfoy! Good show!

And since then, the school had gone crazy. He didn't know what he'd started, or how, but it was truly magnificent. His Dad had wanted 'disturbance' and 'mayhem' - well, he'd sure as hell got it.

He'd got his bloody bird back too. Damn thing. Draco's hands were gouged raw where the Bonxie had pecked out with his razor sharp, hooked beak. Merlin knows how his father had trained him at all! Draco didn't want to think about it. The idea of Lucius devoting painstaking hours, and all his residual magic, to instilling a basic homing discipline into that raucous gull, sickened him. The indignity of it! The desperation…

He'd gone directly to the Owlery from Snape's office, once he'd shaken off Granger and her side-kick. The Great Skua had pushed Pig off the ledge where he usually huddled - the Little Owl's talons were too tiny to grip the perches - and was 'roosting' there, fat and heavy after four days of no exercise and free fish. It uttered a warning 'tuc-tuc' and eyed Draco with beady malevolence. Sticking his arm out in the traditional summoning position (and wishing he'd worn a gauntlet) Draco gave a low whistle. If seagulls could spit, this charmer would have gobbed a beauty then and there - he had no respect for the thin, white, young human.

"Oh, for Merlin's sake!" Draco had tried playing 'nice', but he hadn't got all day. He whipped out his wand and zapped the bird with a light Stupefy! The spell was in no hurry. It meandered upwards through the night, a ripple of invisible unconsciousness, swaying through the air, looping about the fascinated bird, and finally wrapping round it like a shawl. In a stupor, the Skua tilted off the ledge and, spinning slowly, drifted to the ground at Draco's feet.

"Stupid wand," muttered the boy, "if you're not careful you'll be sent back to Ollivander's for a re-bore." The silly thing still worked, after a fashion, but Draco was sick of all his spells being so 'twirly'…

Very carefully, he put his wand to his forehead, extracted the glistening, spangled silver strands of stolen thought, and transferred them to the stunned bird. The factual information was more stringy, still gossamer thin, but strong as elven silk; the happy thoughts mere dancing wisps. Who would have supposed that Snape would have had happy thoughts? And why did he keep them in the Pensieve? Was happiness a secret to be ashamed of, or something too valuable to lose, too precious to share?

They were memories of Hogwarts in the days before the rise of Voldemort, when Lucius had been Snape's mentor at school. The boys had been friends; these were joint recollections. There were powerful, positive feelings: friendship, admiration, gratitude. They would be Lucius' adopted thoughts soon, sustaining him through despair when all other joy had been sucked from his soul.

"Enervate!" The Skua squawked balefully as the spell wobbled into it, and then launched into the air with an angry screech. Wings beating frantically, it plunged and swooped round the tower, diving at Draco, striking out at him as though he were a trespassing Cormorant, and then rising again in a flapping panic, crazed by the matrix of alien ideas piggy-backing his brain.

Then it had soared out into the December night.

X X X

"Hadn't we better tell someone about this wand bug? Shouldn't we go and see Dumbledore?" Harry insisted. He'd almost said "or Snape", but it seemed a bit like 'running to daddy'. Not cool. "Everybody should be told, really. They have a right to know."

"Yes, but…" Neville raised a mild protest.

"Oh, I should have known there'd be a 'but'. There's always a 'but'. What is it this time? What haven't you told me now?" Harry felt that the other two were way ahead of him in their analysis of the situation and its possible ramifications and consequences.

"Well, for one thing, if we've worked it out this far, don't you think the staff will have too? They're not daft," said Hermione.

"They're not herbologists, either though," Neville reminded her.

"True. The problem is, Harry, we're not exactly sure about the next bit. Neville says there's such a thing as a 'devolutionary virus'…"

"I'd hardly make it up!" remonstrated Neville.

"Alright then, if you're so clever. You explain it to Harry!" The lack of sleep was beginning to tell on Hermione; she was getting short-tempered.

"It's like this, Harry. Think about the peculiar things that have been going off when we're doin' a spot of magic - what sort of pattern emerges? Do they have anything in common? As you said, we've got Ron and Ginny, and your wand burning up, and mine as sticky as if I keep it in a tub of treacle, and Hermione here with her hose-pipe…"

"You've not seen my latest accomplishment, have you?" Hermione gave an anaemic laugh. "Watch!"

Pointing her wand directly at another of the comfortable chairs she called out,

"Incendio!"

Harry cringed, waiting for the chair to explode into a fireball that would ignite the entire Common Room. Instead, a fountain of yellow, watery drops whooshed from the tip of her wand, soaking half the room in a shower of soft rain.

"Crikey!"

"Daresay I might have predicted that: what would you expect from Laburnum watereri Vossii, springy, with an Augurey feather core? Double-whammy. That wand couldn't right well do anything else," Neville pronounced, sounding scholarly and authoritative now that he was back in plant territory. "It's her wand, Harry! It's made of Laburnum wood. Do you know what the common gardeners' name is for Laburnum? No? Golden Rain!"

Harry didn't understand completely yet, but he sensed he was on the threshold of something momentous.

"Recognise this?" Neville held out a familiar stick, eleven inches long, and supple...

"That's my wand!" cried Harry. "But it can't be! There was nothing left of it but ashes. Where did you get it? Hey! Don't tell me this has been some huge wind-up all along? Did you nick it, and shove cinders in my pocket? Are you both in on this? Why - "

"It was on your bedside table, when I woke you up this morning," said Neville stolidly, ignoring the accusations. "Try it - see if it works. But, I wouldn't use Incendio, if I were you, just in case…"

Harry took the wand gingerly. It felt smooth and warm, and his fingers tingled with incipient magic as he gripped it more tightly. The memory of his lacerated hand, beaded with blood, stayed him: what if it happened again? Did he want to go through that again?

"Accio cushion!" he exclaimed, shutting his eyes and tensing his fist, waiting for the pain to begin. The feather-stuffed pad hit him with sufficient force to knock him backwards.

"Here, have a cushion!" he grinned at Hermione.

And then it finally clicked. Harry stared at his new wand, re-born from the ashes, with awe.

"Holly, with a Phoenix feather core!" he murmured.

"By 'eck!" cried Neville. "I think he's got it!"

"You make it sound like 'My Fair Lady.'" Hermione smiled.

"Let me get this straight," said Harry, suddenly sharing their excitement. "The Holly minced my hand, and the Phoenix core incinerated and regenerated my wand? So, when Neville talks about the 'devolutionary' thingy he means that the virus is making our wands behave like the wood they were originally made from…"

"It's rather more complicated than that." Hermione tried to clarify. "From what we've seen, the wands are showing a tendency to manifest attributes of the parent tree. Like the twins, in sick bay? Well, their wands wouldn't have had pine cones growing out of them, would they? However…"

Harry sighed. Life was never simple.

"…however, depending on their magical component, the wands may distort or exaggerate those attributes; or in other cases it looks as though the magical core is dominant. Some wands seem to be 'sicker' than others; some only go funny when a spell is cast, while others - like Ron's - seem to have a continuous effect. Some simply create foliage or branches every time they're used. It may be that the virus is mutating, or it may just affect different wands in different ways. That's why we're compiling the list showing everybody's wand wood and magical element - it'll back up the theory if we can prove there's a pattern. Can we just double-check, by the way - Ron's new wand, what is it?"

"Willow," Harry replied, "Weeping Willow, with a Unicorn tail hair core."

"He's lucky he hasn't grown a bloody great horn," said Neville. "Or a tail!"

"And Ginny's?"

"I'm not so sure about that. I wouldn't swear to it, but I think I remember her saying it was -"

"Firethorn?" butted-in Neville, testing his theory. Harry nodded in amazement.

"And mine," said Neville, "as you might have guessed by now, is Maple wood with Acromantula silk. Both awfully sticky! It's been a blessed nuisance, I must say - my cloak pocket's like a right pot of jam."

"Don't worry about that." Suddenly Harry was much more cheerful. Having his wand back made him feel whole again. "If I can do magic, then I can cure everybody else, can't I? Give us your wand, Nev."

Doubtfully, Neville handed it over.

"What do I say?" asked Harry, less confident now.

"Start with a normal Healing Spell," suggested Hermione, "and if that doesn't work, we can try Extraction or Banishment or Exorcism, or… There must be a Kill Viral Pathogen spell somewhere."

Harry prised Neville's wand from the table where it had welded itself like an abandoned Sugar Quill, and aimed.

"Virgammedico! Deputresco! Expellimorbum!"

And so on. After each attempt, Neville hopefully pointed it at the log-basket, and pronounced, "Accio stick", and each time the logs unhelpfully transfigured themselves into chunky sticks of pink and white striped seaside rock, with the name Longbottom running through them in multi-coloured candy lettering.

"Oh, call it a day, Harry. Otherwise Neville'll have to open a sweet shop," sighed Hermione, dispirited. "It was worth a try."

They stared at each other, despondently.

Harry was thinking back to their original question, before they had become bogged down in explanations. What earthly relevance could James Potter have to the current crisis?

"It's no big deal," Hermione yawned. "It's for the list. Professor McGonagall's under sedation, so we won't be able to ask her about her wand."

"Nope. I'm still not with you. Where does James fit in?"

"It's a bit of a long shot… What was James' best subject at school? Transfiguration, right? And didn't Remus or somebody tell us that James' wand was specially suited for it? Isn't that why he was such a fantastic Animagus? We thought there was an off-chance that McGonagall might have something similar. Well, can you remember, Harry, what it was?"

Harry could. In the days when he believed James to be his father he had gleaned every scrap of information about him, and treasured them all…

"Mahogany."

Hermione gasped and Neville, looking self-satisfied, chalked up an invisible mark in the air. He was ready to bet, too, that McGonagall's magical core was something to do with shy, dancing Mooncalves, if he could find any takers…

"And Snape's wand?" Hermione was busily filling-in the columns on her chart. It was almost a formality, but, even so, Harry became guarded. Wands were, after all, one's private property.

"I think that's his business, don't you? Why don't you ask him? But he may not tell you; he might not want you to know." He hedged, covering for Snape.

"Why ever not? God, he's a difficult so and so! It's just a wand, for goodness' sake! That would be just like him - being bloody-minded for the sheer hell of it. I'm sorry, Harry, I know he's your father and everything, but I've just about had it up to here - " - she touched her forehead in a shaky salute – " - with that man. It's not my fault that my hair's been thinking it's raining all the time!" she complained, with a hint of the Moaning Myrtles. She hadn't forgiven Snape's insult.

Harry grimaced. He'd always tried to avoid girls when they were tired, weepy or grumbling about their hair, clothes or figures. It had worked for him so far. But he could hardly avoid Hermione now.

"I think he quite likes you really - he respects your 'mental acuity'." He tried to placate her, using one of Snape's own phrases. The girl huffed:

"Huh. Funny way of showing it."

Neville had been sitting quietly for a while, thoughtfully tapping the end of his wand against his teeth and giving it the occasional lick. Little frowns and tics scudded across his face like clouds on a blustery day, as he worked and worried at the facts before him. Like examining a diseased plant specimen, he picked at scab and rot, peeling away layers of deadwood 'til he reached the true, unblemished heart of the matter.

"Snape can't keep it a secret for ever. It's bound to come out sooner or later. Anyway, it's not as though it's a crime," he commented, revealing a depth of knowledge and understanding that took Harry by surprise. Neville met his gaze steadily.

"If I can hazard a guess, Harry, so can others. Snape's wand - it's Rosewood, isn't it?"

Dumbly, Harry nodded. It felt like a betrayal.

From her comfy chair, Hermione absorbed this with wide, bush-baby eyes, instantly grasping the implication. She wasn't the brightest student in the school for nothing.

"But that means - ?" she gasped.

"Yes."

The use of pure Rosewood in wand-making was traditionally and strictly reserved for wizards of Veela descent. The wood itself was not remarkable in its appearance - it might easily be mistaken for teak or cherry or any of a number of tropical hardwoods, so Snape's secret had remained safe within its fine, French-polished grain. Until now.

"Could be awkward. He won't want that coming out in public," suggested Neville.

"No," Harry agreed, not knowing whether to explain about Snape's family or maintain the enigma. As though by tacit consent, none of them mentioned the term 'Veela'.1

A wave of contrition had slammed into Hermione so hard that she was shocked, and could only murmur,

"Oh, that poor man! No wonder he's been in such a state!"

And Harry had known about this all along. For how long, she wondered? She watched him now, wrestling with friendship and the conflicting demands of this other - what was it? - duty? obligation? love? There was so much more going on between those two - Harry and Snape - than you would ever imagine from the cool, blasé way they behaved towards one another. How many more secrets was Harry obediently keeping on his father's behalf? How had Snape won him over? Whatever could the man have done to deserve or inspire such loyalty?

She had always done her best to encourage Harry to accept his relationship with Snape, even when his actions struck her as unnecessarily harsh or unpleasant - family bonds had to transcend petty grievances. She acknowledged that the Potions master had certain qualities: she could tell, for example, that, in his own undemonstrative way, he cared about Harry; but sometimes – like today - she still found his behaviour intolerably cruel, his manner rude and offensive. She was going to have to make more of an effort to like Snape - for Harry's sake. Perhaps over Christmas she would get to know him a little better…

"So you see, Harry, we couldn't just rush about blurting out my theory - people could have got upset." Neville was still talking. He could be tactful when he wanted to. "You'd better go and see him… explain things." This seemed an ideal solution to Neville - a dragon-avoidance tactic.

From the dormitory upstairs came the heavy, lumbering thumps of adolescent footsteps. Harry glanced at his watch.

"Hell, if that lazy lot are getting up, it means the rest of the school will all be in breakfast by now… Give me a second to get dressed, Neville. We'll have to try and catch Snape in Hall."

Up in his room he placed his wand back into his cloak pocket, almost reverently.

"Welcome back," he whispered.

X X X

In the skies above the Pentland Firth, a plump, puffing Great Skua was winging through the morning mists, heading out across the North Sea towards Shetland, to the islands, and home to his nest on the rocky ledge in the wall of the prison fortress of Azkaban.

X X X

End of Chapter. Next Chapter: DISCOVERIES. The wands run riot, and the pressure is on Neville to save the day…

1. Snape's Veela connection is discussed in 'Snape's Confession', chapter 4. I haven't made it a major issue here, just another complication in the mix.