This story was written before the release of "Harry Potter and the Half-Blood Prince". That doesn't really matter to the plot at all, but since Half-Blood Prince changed everything I knew about Snape, I thought I would mention it.

This story first appeared on Sycophant Hex's Occlumency archive under the penname "mouse". You can find more of my stories hosted there.

Disclaimer: Rowling has not yet noticed me frolicking in the world that she built, because none of her money sticks to my feet while I'm here.
The Silver Potion

Snape turned at the sound - which was a rushing noise, like a waterfall, except with a ringing musical note threaded through it.

Longbottom had pasted himself against the wall, his eyes wide with fright. The boy's fellow Gryffindors were standing well back too, also staring at the cauldron. The surface of Neville's potion was boiling madly, far more wildly than it should be, given that the flames beneath the cauldron were low. The liquid itself was silvery-white and opalescent, glowing faintly, with subtle rainbow colours swirling over its surface like an oil slick. A fair amount of it had boiled over the edge of cauldron and was now blackening on the outside of the pot, giving off a smell like cedar.

'Merlin's tits', thought Snape. 'What's he done now? You simply cannot make the draught of enlightenment do that.'

Snape crossed the classroom in seven long paces, moving so quickly that the hem of his robe snapped against Pansy Parkinson's ankle - apparently painfully, given the little hiss she let out. Snape didn't spare the girl a glance; he kept his eyes boring into Neville Longbottom's.

"Your idiocy reaches heights I never dreamed possible, Longbottom," he said. "Congratulations; your stupidity has officially exceeded my intellect. There should be an award. Even I cannot fathom precisely how you managed to botch the draught of enlightenment this badly."

His Slytherins giggled. The Gryffindors kept silent; Snape could almost smell their collective shame - well deserved, given that Neville was one of them.

As usual, Longbottom's lip was already trembling, and the boy appeared to be trying to dig his way through the wall with his shoulderblades. Switch brown hair for blond, and it might have been Peter Pettigrew standing there, quailing in terror before old Professor Potionum in Snape's fifth year. Now that woman had been tough; Neville was getting it easy, really, taking Potions from Snape.

"What step were you on, Longbottom?" said Snape, gesturing to the list of instructions on the blackboard. He was intrigued, despite his irritation at the boy. Snape wouldn't have admitted it to most people, but the only potion he'd ever seen that looked even remotely like this one was a brew that very definitely fell under the category of "Dark Magic". He'd only brewed it once himself - and if the Ministry of Magic ever found that out, they'd give him a six-month stay in Azkaban. What had Longbottom done?

"I - I - I don't remember," said Neville in the tiniest of voices.

"I'm asking you what you just did! Just now!" snapped Snape. "How can you not remember that, you stupid boy?"

Neville might be getting more agitated by the second, but his potion had calmed now, and was shining beautifully in the bottom of the copper cauldron, little tendrils of silvery steam twirling and dancing over its still surface.

"I w-was putting in the chopped gillyweed, Professor," said Neville, pointing to a pile of mangled greyish plants. The hand he pointed with had a fresh cut on it. "And then it just went..." Snape missed the last word, because Neville's voice was trailing off as he spoke.

Snape stared at plants on the cutting board, pressing his lips together in frustration. When he felt able to contain his anger, he said silkily, "That's not gillyweed, Longbottom."

Neville's eyes swivelled over to the chopped plants, and an expression of dread crept across the boy's face.

"That's asphodel. You got the wrong ingredient out of the store cupboard. Could you possibly be more obtuse, Longbottom? Does your incompetence know any bounds? At all?"

"Anyone could have made that mistake!"

Snape straightened, and turned slowly. Harry Potter, of course. No other student would have dared question his authority, especially in such a belligerent fashion.

Snape's stare caused Harry to look sulky, rather than afraid or - Merlin forbid - regretful. It was infuriating. Like father, like son.

"Five points from Gryffindor," said Snape quietly. "And I'm not done yet, so hold your tongue, Potter, lest you make this day even more unfortunate for your house than it already is going to be."

Harry opened his mouth to retort, but - Snape was pleased to see - Ron Weasley silenced his friend with a sharp kick behind their cauldron. At least some Gryffindors had enough sense to know when not to test his temper; it was a lesson very few Slytherins ever had to be taught twice. Snape turned back to Longbottom, who trembled afresh.

Why waste such spontaneous terror. Rather than speaking, Snape idly picked up Neville's steel ladle - he shouldn't even be using a steel ladle, it should be copper - and tapped it against the cauldron slowly, watching Neville turning to jelly under the weight of his gaze. Yes; this was so much more satisfying than trying to stare down Potter.

"What does it take to get anything into that inpenetrable skull of yours, boy?" Snape asked quietly. "It will be such a joy when you finally leave my classroom for good." Neville dropped his eyes, and stared at the floor miserably. He'd be crying soon; Snape reluctanctly decided to back off before the boy became embarassing. Snape flipped the ladle into the cauldron with a sharp clang, and said -

- nothing, because the moment the ladle hit the silver potion, the liquid turned black, and roared back to a boil, its consistency suddenly like molten tar. Snape only had time to glance down at it in alarm, and then the whole mess exploded up into his face with a gigantic burping noise.

The potion couldn't have been any hotter than simmering water, but it burned furiously everywhere it touched him - Snape gasped in spite of himself, and a bitter taste entered his mouth. He fought not to swallow, his face stinging mercilessly.

"Evanesco!" a girl shouted, and both the burning and the bitterness were abruptly gone. Snape opened his eyes, panting a little from the shock.

Hermione Granger was in front of him with her wand out and her face very white.

They stared at one another for a heartbeat, and then Hermione said, "What is your name?"

"Severus Snape."

"Do you know where you are?"

"In the dungeons, Hogwarts castle."

"Close your eyes and touch the tip of your finger to the tip of your nose."

Snape did so, his anger beginning to return. He could already tell that he was fine - but she was right to make him go through the whole drill.

"Balance on one leg?"

He did that as well, held the pose, then put his foot back down and looked at Hermione.

"Any obvious external symptoms?" he asked her calmly.

Hermione studied him a moment, and then said, "No. You look a bit scalded. Nothing else."

The girl sounded like she'd had a good scare; her face was still very pale. Snape turned to look at Neville. In comparison, Hermione was positively rosy.

"My compliments, Miss Granger, on your cool-headedness," said Snape evenly, keeping his eyes fixed murderously on Neville. "And on you knowing the full emergency procedure for accidental potion exposure." Snape looked down at the cauldron. The handle of Neville's ladle lay at the bottom of it, but the dipper half had been eaten away entirely. He should have known better than to drop a ladle with iron content into an unknown potion, but who expected student potions to get that volatile? Snape wasn't going to admit that he'd done anything wrong, of course. He pursed his lips, and said grudgingly, "Five points to Gryffindor, Miss Granger."

The Gryffindors collectively made a small whispery noise of surprise - Snape supposed it had been rather a few years since he'd given a Gryffindor any points. He looked up at Neville, giving them all a moment to enjoy it, and then said in a quiet but cutting voice, "And fifty points from Gryffindor for Longbottom's abysmal incompetence."

There was a flurry of supressed giggles from the Slytherin half of the class. "You will see me after class to arrange your detentions for this week, Longbottom," continued Snape. "You are very lucky that your obscene lack of talent resulted in a potion of no magical consequence, or I would have had you expelled from Hogwarts as the menace to life and limb that you are."

Neville looked on the brink of waterworks again, so Snape turned and swept to the front of the classroom. He had some burn remedies prepared there; his face was smarting ferociously.

Snape never took any pleasure in getting ready for the day. It was always just another day, with just the same frustrations and annoyances as every other day. He almost missed being a Death Eater.

The morning sun would have lightened his rooms a little, through the high small window into the dungeons, but he never bothered with opening the blinds. He'd only want them shut again when he came back to sleep.

Snape spared as little time as possible dressing and making himself presentable. He only looked in the mirror in order to shave quickly with his wand, but when he had finished, he paused, looking at his face for a moment.

It wasn't a face he'd ever made peace with; he didn't like the way he looked. There was just no getting used to his father's nose, and he was looking more and more like his father every day, it seemed.

Except maybe today. Snape pushed his hair back and hooked it behind his ears, still studying his reflection. He didn't actually look too bad, for a man inching toward forty.

Snape's mouth twisted into a sneer. It was probably an unforseen side-benefit of having greasy skin; he wasn't drying out and getting wrinkly at quite the same rate as everyone else. Lucky him.

He pocketed his wand, shook his hair back over his face, and went to breakfast.

Neville never failed to scarper in abject cowardice at the end of his detentions with Snape. 'And we've had enough of them, over the years, that you'd think he'd be used to them by now,' thought Snape sourly as he locked the door of the Potions classroom, Longbottom's robes whipping out of sight around the far end of the corridor. 'I wonder if I shall miss him when he's gone. It will be like the gap left in your mouth when they finally pull that agonizing, rotten tooth out.'

"All finished with Mr. Longbottom then, Severus?" said a mild voice behind him. Snape whirled, one hand hunting instinctively for the pocket where he kept his wand. He stopped himself with an effort, and consciously made himself relax.

"Don't do that, Albus," he said through gritted teeth. "You walk like a bloody cat."

Albus Dumbledore grinned his little-boy's grin, blue eyes twinkling with mischief. "I know. And let me say that I considered it the highest compliment I've ever been paid, the day you admitted that I was the only person who could sneak up on you. I was wondering if you'd like to have a drink with me, Severus. It's a lovely clear evening, and I wanted to watch the moon rise."

"I suppose," said Snape, without much enthusiasm. "Just one, though. I'm tired."

But Dumbledore was staring at him suddenly, intently.

"What?" said Snape.

"What have you done?" asked Dumbledore.

"What are you talking about, Albus?" said Snape. Dumbledore didn't answer, but instead raised his wrinkled, blue-veined hands and pushed the hair away from Snape's face with his fingertips. It was a gentle gesture, but Snape flinched away; he didn't like being touched.

"What is it?" he said, feeling thoroughly annoyed now.

"What have you done?" repeated Dumbledore. He was looking directly into Snape's eyes, and the hint of steel in his voice let Snape know that Dumbledore was not being light-hearted anymore.

"I don't know what you're talking about, Albus," said Snape quietly, letting the honesty that he knew Dumbledore would be able to sense in him do the convincing.

Albus put his hands on either side of Snape's face and tilted it to catch the light better. Snape had to work to keep himself from pulling away from the contact. After what felt like a pocket-sized eternity, Dumbledore finally released him, looking concerned.

"Tell me about Neville's potion, Severus."

"What potion?" said Snape blankly, and then blinked, "Oh - the one I got doused with yesterday? What do you want to know about it?"

"What was it? What did he do wrong?"

"I haven't the foggiest. It wasn't like anything I'd ever seen before," said Snape. That was a small lie, but Dumbledore either didn't catch it, or let it go. "Well," added Snape after a moment's thought, "I know he used asphodel instead of gillyweed, but that couldn't have made it go silver, or lower the vapour pressure that much. He had to have either missed a few steps, or repeated a few. Maybe both; Circe's arse, but the boy can botch things like you can't imagine."

"Everyone is good at something," said Dumbledore mildly, "but Potions are not what Neville Longbottom is good at. I want you to come to the hospital wing with me, Severus."

"Why?" said Snape, with genuine bemusement.

"It's hard to tell, but I think you're right," said Madam Pomfrey, touching her wand to the bottom of Snape's chin to make him raise his face to the light again. Snape wondered about that. He'd never told Poppy that he hated to be touched, but she'd obviously figured it out at some point because she had, ever since he was a child, wordlessly refrained from doing so unless she needed to. "He's perhaps five years younger than he should be. It's a subtle difference in this age bracket. You'd notice it straight away if one of the students suddenly got five years younger."

"Any idea what could cause this?" asked Dumbledore.

"None. Some of the ingredients in Shrinking Solution can have this effect, but they work faster and are very unstable. The effects are short-lived generally. Severus could tell you more about them than I could."

"Indeed," said Dumbledore, sitting down beside Snape. "What think you, Severus?"

Snape gazed at the headmaster silently, turning over the ingredients of the draught of enlightenment in his mind. How would asphodel interact with them? What could Neville have possibly done? "I'll have to sit down and try to work through the reactions on paper," he said eventually. "No ideas present themselves, immediately." Snape snorted. "Although, if we can figure out what he did do, Neville will be a millionaire. A potion that reverses aging? Trophy wives the world over will build shrines to him."

"Provided that the process can be stopped," said Dumbledore. Snape looked at him sharply.

"Yes," he said. "Provided that."

"I want you to come in here tomorrow morning," said Madame Pomfrey to Snape. "Or sooner if new symptoms appear. Those are medi-witch's orders; understood?"

Snape stared at his reflection the next morning. It was obvious even to him now. He looked like a man in his late twenties. The hint of slackening skin around his jawline had disappeared, and the fine lines bracketing his mouth and dividing the flesh between his eyebrows were almost gone.

Oddly, the thing that made him the most nervous about it all was the fact that his students were going to notice. Should he explain? Or just carry on, with cast-iron disdain for their staring? Maybe they wouldn't notice after all; children tended to think that everyone over the age of twenty was indiffentiably ancient.

At his examination, Madame Pomfrey frowned at Snape, and told him exactly what he'd already decided for himself - that the potion's effects were still active. At breakfast, the other teachers kept glancing at Snape; Dumbledore must have told them something.

The students did notice; curse their sharp little eyes. None of them had the nerve to say anything to him however, except for one or two of his Slytherins. And they seemed to think Snape had done this for cosmetic reasons. The vacuous conceit implied by this assumption made Snape grind his teeth, and he made sure that those few students brave enough - or ingratiating enough - to mention his youthful face to him were set straight on what had really happened. Hopefully, they'd spread the word. He didn't want anyone thinking he was Gilderoy Lockhart or something.

By the time Neville's timid knock rattled the classroom door, Snape was in a foul mood, and more than ready to vent some of his ire on his intellectual nemesis. However, when Snape waved the door open with his wand, both Dumbledore and Neville came in, Dumbledore with a comforting hand resting on the boy's shoulder. Snape scowled at them both.

"I think," said Dumbledore, "that we should cancel the rest of Mr. Longbottom's detentions, Professor Snape, given the seriousness of the circumstances. I have taken the liberty of telling Mr. Longbottom what we think his potion did, and he has offered us his help in determining what it was, so that we may find an antidote to it."

Snape snorted with laughter, bringing a look of anger to Dumbledore's face and a look of humiliation to Neville's.

"You think he can help me?" said Snape, not bothering to keep the amusement out of his voice. "You think Neville Longbottom is going to help me determine the effects of an incorrectly prepared potion made with ill-determined starting ingredients? Why, I never realised he was such an expert in forensic magic. Certainly; let me get him some scratch parchment so he can start his theoretical calculations."

"Mr. Longbottom's concern for you is quite genuine, Professor Snape," said Dumbledore. "You are being both insulting and ungrateful."

Snape bit back his derision, and said tightly, "I don't see how he could help me, Albus. I know of only about three wizards in all of England who might be more capable than I am of sorting this mess out."

"I can try to remember what I did," said Neville.

"You? Remember something?" said Snape in a light, dangerous tone, but the look in Dumbledore's eyes was far more dangerous than the words. Snape cut off the rest of his comment.

"I - I thought I might have done one step twice, but I wasn't sure. And I'm not sure now which one it was, but if I looked at the list of instructions again, I might recall," said Neville. "Hermione might be able to help too, because she gave me a hint at one point, so she must have been watching some of what I was doing."

"If you will unlock the stores cupboard, Severus," said Dumbledore, "I will work with Neville to try to reproduce the original potion. You may assist us, or oversee us, as you like - but I thought you might prefer to use the time to work on your calculations uninterrupted.

Snape snorted. "Fine," he said, waving his wand at the cupboard at the back of the room, and then plucking his quill from the cup at the edge of his desk. "I wish you both a merry time of it. If something looks dangerous, call me over to check it, Headmaster. Knowing Longbottom, it's probably lethal."

Neville looked disraught at the comment, and Dumbledore shot Snape a very angry look. Snape just curled his lip, and bent over his work.

Working on theory always caused Snape to lose track of the time. He only looked up when he ran out of spare parchment, and was surprised to see Dumbledore sitting in front of his desk, studying him.

"Where's Longbottom?" asked Snape, noticing suddenly that his eyes felt scratchy and tired. He rubbed them, and yawned.

"I sent him to bed an hour ago. It's nearly midnight. Did you really not hear him leave?"

"I miss a lot when I'm concentrating," said Snape. Then he added, "But that's the only time I miss anything."

"You know," said Dumbledore, continuing to study Snape, "this is proving to be a most strange exercise in nostalgia, watching you grow younger."

"Did the two of you come up with anything?" Snape asked shortly.

"We think we know which step he repeated, but there's more to it than that," said Dumbledore. "The potion we brewed tonight was muck. We shall have to ask Miss Granger if she can remember anything relevant."

"Fifth years to the rescue," sneered Snape. "I'll be back in nappies, before that pair manages to do anything of note in my Potions classroom."

"In nappies, or worse," said Dumbledore sharply. Snape frowned at him. "You do realise," continued the Headmaster, "that if this potion's effects don't slow down, you're going to be dead within a few days? I don't see why you aren't taking this more seriously, Severus. Right now, you barely look older than the day I hired you."

"I'm going to sort it out, Albus," said Snape peevishly. "There's nothing Neville can manage that I can't reverse-engineer. If we can sort out the ingredients list, and the steps that produced that particular potion, then making an antidote for it is straightforward. Those bunglers at St. Mungo's could do it in about an hour."

"Well, I wish you wouldn't joke about lethal potions to Neville. It's cruel. He's utterly horrified at the prospect of his error possibly costing someone their life." The Headmaster paused, looking at Snape over the top of his glasses. "He's a kind-hearted boy, Severus," he said, "and that's a worthier attribute than any intellectual talent you could name for me. Have your reaction calculations turned up anything?"

"I've got a few leads," shrugged Snape.

"A few leads?" said Dumbledore sadly, getting to his feet. "That's not enough to let me sleep easy tonight. But we should both make the attempt, I suppose. Go to bed, Severus; no pacing around the hallways thinking, tonight. Take a draught of dreamless sleep if you have to."

"You're over-reacting, Albus," said Snape irritably, also standing up.

"I care about what happens to you, lad," said Albus gently. Then he added in a firmer tone, "And you're relieved of your teaching duties until further notice, Severus. If I can't find a substitute to take your classes, then we'll just have to cancel them. I want you working on this exclusively from now on."

"I can't!" said Snape. "You can't! Albus, my fourth year students are in the middle of brewing potions with Andarice in them! If they don't work on them tomorrow, it will over-age and be ruined. That stuff is expensive! And my seventh years are just starting magic distillation theory - that comes up on their NEWTS every year like clockwork!"

"A life is at stake, Severus," said Albus. "Yours, to be specific. Please re-examine your priorities." Dumbledore's whiskers twitched slightly, a hint of a smile hiding somewhere under them. "Besides," he said, "by tomorrow morning, you're going to look like a seventh year yourself. It might be harder than you think, keeping order in the classroom, in your condition."

Walking to the breakfast table the next morning wasn't quite underpants-on-display embarrassing, but it was close. Snape seated himself at the staff table, trying to ignore the stares of his colleagues and the hush that was falling over the Great Hall as students turned in their seats to get a better look at him. His face felt hot, but he kept his expression impassive.

"I could use a bit of that treatment," said Flitwick, leaning over with a smile. "Especially the slimming effects; but only if you can find a way to halt the process. How is that going?"

"It's a bit of theory to work through for me; that's all," said Snape.

"You hardly look graduated!" Flitwick was actually grinning at him.

"Yes, well my looks are irrelevant," snapped Snape. "They always have been. I'm the same person I always was."

"Might an aging potion help?" said Flitwick a bit more kindly.

"It would be a temporary fix, and I don't want to risk funny interactions anyway. A simple antidote is all that's required," said Snape. "I'll probably have it by the end of today."

Flitwick nodded, smiled at him, and went back to his breakfast.

A tap on the door made Snape jump, and glance up from his calculations. "Enter," he said tersely.

Draco opened the door, smiled at him, and came in, with Pansy at his heels.

"Hi Professor," said Draco sauntering forward and taking a seat on one of the desks. "You're not busy, are you? Since Potions was cancelled this afternoon, we thought we'd use the break to come by and see how you are."

"Very kind of you, Draco, but I am busy. It will have to be a short visit," said Snape.

"Okay." Draco grinned and swung his dangling feet. The boy had a knack for being endearing when he wanted to be. "Crabbe and Goyle would have come too, but they're catching up on homework. Scared to death of their OWLs, of course."

"They should be," said Snape quietly.

Pansy had leaned against the desk that Draco was sitting on, and was studying Snape's face. Snape turned his head and stared back at her impassively. Pansy's trademark sly grin began to creep across her face. She wasn't a beauty, but she did have a sort of wild-girl charisma that Snape had noticed the boys responding to.

"You look even younger than you did this morning, Professor," she said.

"Yes, the process is unfortunately proving to be rather fast-paced," said Snape.

"But it's slow-acting - for a potion - isn't it?" said Draco. "Most potions are made to work instantaneously. You add the ingredients with a mind toward getting everything to react at the same time as you add the most volatile ingredient, and then, after that initial reaction, you add further ingredients to stabilise the essential magic within the organic matrix. The time it takes the potion to work is usually determined by the volatility of the most unstable ingredient. So if this potion is working slowly on you, that means that the volatile elements in the draught of enlightenment weren't involved in whatever reaction produced the essential magic that you ingested."

Snape felt the corner of his mouth quirk upward. "And that is why you are one of my top students, Draco. Do you know that I have seventh year students who don't grasp theory as well as you do?"

"Why thank you Professor," said Draco pleasantly - and just a trace smugly.

"And if you applied yourself," Snape added in a drier tone, "you would be the top student, rather than "one of" the top students. I would have thought your personal dislike for Miss Granger would be more than enough incentive to work harder, Draco. It does not become a Slytherin, to settle for second-best."

Draco grimaced, but didn't reply. Pansy, who had schooled her face into cool nonchalance during the technical discussion, frowned at Snape, and said, "But you will be alright, won't you Professor? You can find an antidote for this?"

Snape's eyes flicked downward to his calculations briefly. How much to admit to? "It's not going as well as I would like," he said slowly, "but nothing that Neville Longbottom can accomplish could possibly be beyond my abilities - excepting his world-class talent for being a complete feather-head, of course. That, I am happy to say, I could not manage."

Draco and Pansy snickered appreciatively.

"Well, we'll let you get back to work then, Professor," said Draco, hopping off the desk. "We want you to find that antidote as soon as you can. Come on, Pansy."

"You go on without me," said Pansy. "I need to ask a question about our last assignment."

Pansy turned back to Snape. She waited until Draco had left, a faint smile flickering across her strange pixie face. Snape stared back, feeling annoyed.

After a few heartbeats, he prompted, "And your question is, Miss Parkinson?"

"Oh, I just said that to get rid of Draco," Pansy said, walking toward his desk with a graceful cat-like saunter. She began to walk around the edge of the desk - to Snape's side. It was a galling broach of his authority, and so he stood up, intending to intimidate her a little.

Snape blinked in surprise, and Pansy's smile turned into a giggle.

"I've got shorter!" said Snape in horror. He only stood a couple of inches taller than Pansy now, rather than the half-foot that he was used to. Pansy dissolved into laughter.

"How old do I look?" Snape demanded.

"About the same age as me," said Pansy, her voice musical with giggles.

"I look fifteen?"

"Maybe sixteen," Pansy said. Snape looked down at himself. His robes were pooling at his feet, and his sleeves were a shade too long. His wrists looked knobblier than they should, too.

Snape looked up again in time to see an expression of determined mischief on Pansy's face. The girl wound her arms around his neck and kissed him hard on the mouth.

"Get off me!" thundered Snape, shoving the girl away far harder than he had intended to. Pansy stumbled back - but she was giggling still, her dark eyes glittering.

"But it can't wait," she said playfully, walking toward him again, using that same cat-like gait. "You'll be too young for me tomorrow."

"I'm too old for you on both days!" sputtered Snape. "You're a fifteen-year-old girl!"

"And you're a fifteen year old boy," said Pansy in an intentionally seductive voice, leaning toward him.

"I'm thirty-six!" Snape raged at her. "Get out of my classroom, you stupid little cow! Get out! Now!"

Pansy just giggled again, and then paused, her head tilted a little, studying his expression closely. Snape felt himself break out in an uncharacteristic cold sweat. Pansy was deciding whether or not to obey him, and "not" would probably involve her kissing him again. And what the hell would he do if that happened?

Snape pulled himself together. "Get out, Miss Parkinson," he said in his deadliest voice, "or you will be in detention for a month, and Slytherin house will be down by one hundred points - as much as that fact would pain me. Regardless of how I look, Miss Parkinson, I am still your Professor!"

Pansy gazed at him a moment longer, then giggled one last time, turned, and sprinted out of the classroom. Snape waited until he was sure she was gone, and then sat down. The screaming, crimson embarrassment of it all! He'd give her that detention anyway, when he was back to normal. Right now however, he was too hot, and the skin between his shoulderblades felt damp. Blasted girl.

Pansy wasn't really interested in him, of course - Snape remembered quite clearly just how unattractive he'd been to girls the first time his body was at this age - she just wanted to find out how much power she had over him. Typical Slytherin. It reminded Snape unpleasantly of some of the games that Bella had used to play when she was young and lovely and toying with the boys who courted her.

The worst part of the incident was that Snape's sixteen-year-old body had been very definitely in favour of Pansy kissing him again. Funny how teenage hormones could cut through an otherwise strong aversion to being touched. And those urges, now awakened, were likely to continue distracting him for the rest of the afternoon. Snape ran his hands through his hair, and tried to shake off the ridiculous teenage emotions. He pulled the sheet of parchment he had been working on back toward himself, picked up his quill.

He didn't even have time to recapture the thread of what he'd been doing before someone rapped on the classroom door again.

Snape looked up. Hermione Granger and Neville Longbottom were standing in the doorway.

"Enter," he said dryly, putting the quill down.

The two students came only a little way into the classroom, and then stood there, staring at him.

"Yes!" said Snape loudly. "I know! Had a good enough eyeful yet? Why are you two here?"

"We - we came to try to figure out what Neville did," said Hermione timidly. "With Potions cancelled, we can get an early start on it."

"Well - begin, then!" said Snape, gesturing violently at the cauldron that Neville had been using the previous evening.

"Party started already?" asked Dumbledore, sticking his head in the door. "Splendid! How are you this afternoon Miss Granger, Mr. Longbottom?"

The students sang a chorus of "Very well, thank you" to the Headmaster, and smiled up at him. Snape curled his lip in disgust.

"You have your list, Neville?" said Dumbledore.

"Yes, Professor," said Neville, holding up a piece of parchment with the Headmaster's writing on it. "Thank you for taking notes last night."

Hermione and Neville settled down to work. Snape overheard Hermione saying, "All right Neville. You start making the potion, and I'll watch and try to recall what I saw you do. Remember to go by the list - you don't want to be doing something different each time..." Dumbledore walked over to Snape's desk.

"It won't work," Snape said to him, quietly enough that the students wouldn't hear.

"Don't be such a pessimist, Severus," said Dumbledore genially. "So - are you looking forward to puberty?"

"I'm not being a pessimist, Albus," said Snape testily. He pushed a sheet of parchment across to Dumbledore. "Look at these equations. I've been working on this all day, and there is just no way to get that list of ingredients to do what I observed! Something formed in Longbottom's potion that had a very low vapour pressure, because the potion boiled like mad while on a moderate flame. Whatever that substance was, it boiled off, and left the stable silver potion behind. But if you take the list of ingredients for the draught of enlightenment, and include asphodel - I'm not even excluding the gillyweed anymore! - you simply cannot make something that volatile, no matter how you prepare the ingredients or what order you mix them in!"

Dumbledore studied the equations carefully. "You're sure?" he said.

"I am certain, Headmaster," said Snape. "I think Longbottom had another wrong ingredient in there, in addition to the asphodel." Snape fiddled with his quill for a moment, and then said tensely, "and unless we can figure out what that was, I'm in real trouble here."

Dumbledore continued to study the reaction calculations for a moment, and then got up and went over to Neville and Hermione.

"Neville," he said, "I want you to try to remember something for me."

Snape snorted in derision at the word "remember". Neville went scarlet, but Dumbledore continued speaking as if he hadn't noticed either thing.

"Professor Snape wonders if you might have had a different incorrect ingredient in there, in addition to the asphodel. Or perhaps something got into the potion by accident. Can you remember anything like that?"

Neville said something so quietly that Snape couldn't make it out. Dumbledore said gently, "Well, do these ingredients look like the ones you were using? Think hard."

Again, Neville's response was too quiet to hear, but Hermione said, "He had all these ingredients, Professor. I remember - he went back to the stores cupboard a second time, and I glanced over to see why. It took me a second, but then I realised he was missing gillyweed, and that he must have gone back to get some. But everything else was there by his cauldron. He had all the right potion ingredients, except for the gillyweed."

Snape scowled. Then he got up and swept - or tried to - over to the stores cupboard. To his annoyance, Snape found he couldn't move as quickly as he was used to without tripping over his over-sized robes. On top of that, he felt clumsy and ill-built right now - seemingly all elbows and knees.

After Snape had been studying the potion ingredients in the cupboard for a while, Dumbledore came over and said, "Checking for cross-contamination?"

"Yes, but everything looks fine," said Snape. "And besides, a trace amount of contamination from any of the ingredients we've got here shouldn't affect a whole cauldron full of potion. Only truly powerful ingredients can do that, and I don't let students handle those unless they're in seventh year. And exceptional."

"Might something have got in there by accident? Tracked in, or caught on sleeve cuff perhaps?" said Dumbledore. "What counts as a powerful potion ingredient?"

"Basilisk venom," said Snape. "The blood of an enemy, or of a dragon. A unicorn's heart. There's lots of things - mostly illegal to obtain - and I keep none of them in here." Snape bit his lip. "I cannot think of a single way in which Neville Longbottom might have got a truly powerful potion ingredient into this classroom by accident."

The evening hadn't gone well, although Snape might have admitted (under duress) that this was probably his own fault.

"You've concocted a potion nearly identical to this one five times this evening, Longbottom! How could you mess up the procedure on this go-around? Even with Miss Granger nurse-maiding you throughout? Can you not even learn by repetition, you dunderhead? What is wrong with you?"

"Severus," said Dumbledore sharply from the doorway - he'd gone off an hour ago to eat dinner - "I think it's time the children went to bed."

"Good news at last!" fumed Snape. "They're certainly accomplishing nothing of worth here, and they distract me!" He stomped over to his desk and sat down.

"Neville, Hermione, thank you so much for your help this evening," said Dumbledore warmly to the two students. "You may go now. You have Professor Snape's and my deepest gratitude for your assistance."

Neville and Hermione both looked at Professor Snape with a mixture of scepticism and fear on their faces. He glared back at them poisonously. Dumbledore, glancing between Snape and the students, smiled and said, "Oh, don't you mind him. You know how ferociously moody teenagers can be."

The look that Snape gave Dumbledore should have incinerated him. Neville and Hermione took one look at his expression, gathered up their belongings, and streaked out of the classroom.

"I AM NOT BEING MOODY!" roared Snape.

"No more so than you normally are, Severus, no," said Dumbledore, a gentle smile on his face.


Snape stopped, and clamped a hand to his throat. Dumbledore made a heroic attempt not to burst out laughing, but failed, and had to lean against a desk for support.

"Did my voice just crack?" said Snape.

"Yes. I'm afraid it did," Dumbledore gasped shakily, nearly crying with mirth.

Snape sat there a moment, clutching his throat. "Good," he said finally. "No more teenage hormones to deal with. That will be a relief."

Dumbledore stopped laughing and stared at him.

"Have you been having trouble with that?" he asked, his voice ringing with amusement. Snape nodded miserably.

"Kept catching myself staring at the curve of Miss Granger's throat, instead of concentrating on what I was doing. No wonder the little blighters in third year never seem to hear a word I say."

Snape folded his arms, and patiently waited for Dumbledore to stop falling about the place laughing.

"It's not funny," he said, when the Headmaster had finally stopped snorting and giggling madly. "I'm over twice their age. I feel like a dirty old man."

"When in fact, you're a dirty young man, which is completely normal and unremarkable. I wouldn't worry about it too much, Severus."

Snape ran his fingers up into his hair and rested his head against his palms for a moment. "Tomorrow, I'm going to be a child," he said. "All of a sudden, I have no time left. I have perhaps two days to live."

"We'll get you through this, Severus," said Dumbledore, suddenly gentle. "We will find your antidote in time. Tonight I sent an owl to St. Mungo's; they're sending two specialists over tomorrow to help us."

"Problem is," said Snape listlessly, "it's hard to find anyone more specialised than me, and I'm stumped, so what good will they do? Why is it so much harder to face a death that you can see coming, as opposed to one that might happen spontaneously at any moment? I'm not afraid of dying; but I can't stand the dread of it."

"Be thou of good hope, Severus," said Dumbledore. He stood up. "And now, may I remind you that I did say it was time for the children to go to bed. That means you also."

Snape sputtered with rage, but Dumbledore just started laughing at him again.

Snape tried to shrink his robes to fit him, but his wand didn't seem to be behaving anymore. He was becoming too young to handle complex charms; his magical abilities had become underdeveloped again.

After much swearing, and multiple attempts, Snape finally had something that was at least wearable. He dressed, and left his rooms to go to breakfast. He nearly walked into Dumbledore coming around a corner, and judging by the gasp the other man let out, it was more of a shock to Dumbledore than it was to him.

Dumbledore stood there, his mouth slightly open, staring at Snape.

"That's rather rude, you know," said Snape, hating his little-boy voice. Sarcasm just didn't work as well in this octave.

"Sorry," said Dumbledore, still looking quite shocked. "I did say that this was proving to be a very strange exercise in nostalgia, Severus. I had forgotten how small you were when you first came to Hogwarts."

"There have been thousands of students through this school, Albus," said Snape peevishly. "I do not believe that you remember me."

"I do," said Dumbledore, his voice holding both sadness and anger. "You were this thin, tiny boy - as pale as a plant that's been kept in the dark." Dumbledore paused, frowning slightly, then said, "And as bruised as a kicked peach." Snape suddenly found he couldn't meet the Headmaster's eyes anymore. "Everytime you came back to Hogwarts from a visit home, you had marks on you, but would never tell anyone where they came from," said Dumbledore. "It drove Poppy and me to distraction. There are very few actions in this world that could make me willingly do harm to another human being, but hurting children is one of them."

"I don't - really," said Snape haltingly, "have time - for nostalgia, right now. Can we move on? I need breakfast, and then I need to get to work."

"Of course," said Dumbledore softly. "You have always found great comfort in your work. But breakfast first."

Breakfast was a nearly painful experience. The students weren't just staring anymore; they were staring and giggling to one another about his appearance.

And his size. Snape had to kneel on his chair to eat his breakfast in comfort, because the table was a little too high for him. He wondered if it might have been wiser to sit with his Slytherin students instead of at the staff table. Most of the students he had passed in the hallways that morning hadn't even recognised him, so he would have been almost invisible sitting among them. Also, the Slytherins were doing the least amount of giggling, and casting him the most worried glances. Snape was quite popular with his students, in his own way. They knew better than to cross him, but they also knew that Snape would deal with their rule infractions in a discreet manner, without alerting either their parents or the Headmaster unless it was completely necessary. They appreciated his protection of them, and of their reputations.

The Gryffindor table was another matter, of course; great merriment was taking place there. Snape glared at Harry and Ron, who kept looking over their shoulders at him, and falling about laughing. Hermione looked huffy, sitting across the table from the two boys, but was saying nothing. The Remus of her generation.

And then, as he was watching, something interesting happened. Snape saw Neville stand up and snap at Harry and Ron - he couldn't quite catch the words, but Neville's tone and posture were clearly angry. The two other boys were shocked silent immediately, and the Gryffindors sitting near them quieted also, everyone staring at Neville, who continued to rant at the other two boys. After perhaps a half-minute of it, Neville turned and stomped away from the table - and out of the Great Hall entirely - in what was clearly a filthy temper. Snape watched him go, surprised - but pleased - to see that soft, silly boy finally showing some backbone. Potter and Weasley didn't laugh again for the rest of the meal, but Granger looked happier.

Snape wandered into the Potions classroom in a distracted, thoughtful mood, and so was surprised to find a man and a woman standing there.

"Well, we are a bit early," the man was saying. He had his back to the door and was staring up at the jars of potion ingredients lining the wall behind Snape's desk. The woman spotted Snape immediately however, and smiled at him.

"Hi there, Sweetie," she said to him. "Are you a Slytherin? Can you tell us where we could find Professor Snape?"

Snape stared at her in outrage. The woman's companion had turned when she spoke, and apparently had realised the gaffe immediately, because he was now cringing. The woman continued to smile at Snape.

"Yes, he's standing right in front of you, you addle-witted sow," said Snape loudly.

The woman's expression turned to one of confusion, but her companion readjusted his face around his gritted teeth to form a rather pained smile. He leaned forward, extending his hand.

"Professor Snape!" he said, "So nice to meet you! I'm Handolin Ronk, and this is my assistant, Renni Spanner."

"My condolences. Better luck next time," said Snape, shaking Handolin's hand but still glaring daggers at Renni.

"She's new," said Handolin apologetically. Renni had apparently realised what she had done now, because her face had gone scarlet and she was avoiding Snape's eye.

"You're the experts from St. Mungo's?" said Snape. "Merlin help me; I had better call my solicitor and start writing my will."

Handolin's smile disappeared, but he said in perfectly cordial voice, "We need to know everything that happened, with as much detail as possible. May we start interviewing you immediately?"

"Certainly," said Snape, gesturing for them to sit at the students' desks, while he went up to the head of the classroom to take his own seat. Safely hidden behind his desk, Snape discreetly pulled his feet up, and kneeled on his chair.

Neville had arrived in the middle of Snape's interview, and haunted the back corner of the room until Handolin and Renni finished. When Snape grudgingly introduced the boy, the two specialists insisted on interviewing him as well.

Snape stood by the cauldron where Neville had been working the previous night, and poured over the notes that Dumbledore had made for the boy. It was a careful summary of their work, but Snape could work out the potion ingredient reactions in his head, and he could see that there was nothing here that was useful. He glanced up at the trio sitting by his desk. Renni seemed to be doing most of the talking, and Neville appeared to like her. She smiled quite a bit, and occasionally said things that made the boy laugh a little. Handolin sat silently, looking at Neville with a polite expression, and taking careful notes of the conversation.

Snape wished fervently that the two specialists weren't there, because he had made a decision last night, and they were a danger to his plan. He - and Neville and Hermione - and Dumbledore - had all been exploring blind alleys. None of the logical means of deducing what Neville's potion had been were working. But Snape had a memory of a potion, brewed only once by his hand, that had looked similar to what Neville had made...

Snape had decided last night that it was time to break his vow to never involve himself with the Dark Arts again.

Snape had a book; he had it hidden within Hogwarts, because as much as Snape dreaded the thought of Dumbledore ever finding out that he still possessed it, he dreaded the thought of the book falling back into Voldemort's hands even more.

Snape hated the fact that he had never been able to bring himself to destroy the book. It contained knowledge, and he couldn't make himself erase something as beautiful as true understanding. The fact that the understanding in this book had been bought with human lives, and could only be used to twist and destroy sickened him - and yet - to wipe it away forever was somehow worse.

To practice Dark Magic was to channel that particular and disturbing type of magic that was able to use the wizard as easily as the wizard could use it. In cases where the Dark magic ran out of control, or was purposefully let out of control, it could feed on the living, as if it were a living thing itself, which preyed on humans and their darkest impulses. Most magic came from the natural earth, and was alive in the same way that soil was - harmless and inert if left alone, but fertile if used. Dark Magic was much more powerful than normal magic because it was not inert - it actively tried to make the magic-user's spells work. But it was much more dangerous than normal magic too, because it would occasionally twist itself out of the magic-user's control, and feed on whoever was available.

Potions, which so often involved killing plants and animals, was a lot closer to being a Dark Art than people liked to talk about. And so it wasn't - Snape had decided last night - much worse than brewing a normal potion, if he just took a look at the book. A look only; he wouldn't be brewing anything in it - he would just be examining the recipes recorded there, for clues to what steps and ingredients had created Neville's iridescent silver potion. And Snape was doing it to save his own life. This was surely an extenuating circumstance.

Snape glanced over at Neville and the two specialists, and then turned and quietly left the classroom. He walked down the hallway, entered his office, and closed the door behind him. Snape walked to his writing desk, pulled the chair out and ducked down. The castle floors were stone blocks, and one of the ones under this desk had a chipped edge.

"Lumos," said Snape, and pointed the light of his wand at the chip. There was a rough patch on it where, if you shone a light at it from the correct angle, the shadows formed the shape of a skull. Snape paused, frowning. His magic was getting weaker. He would be able to reveal the book - that was a relatively simple charm, if you knew the key - but he wasn't going to be able to hide it again afterward.

Snape sighed, pressed the end of his wand against the shadow-skull, and said "Silith-lin". The stone suddenly rippled, then drained away in liquid form, revealing a heavy brown book, bound in leather and without a title. Snape picked it up, crawled back out, and put the book on his desk. He stood staring at it a moment, and then took a piece of parchment and a quill and wrote: "Bequeathed to Albus Dumbledore, in the event of my death. Dispose of this, Albus."

Snape signed the note. After a moment of internal struggle, he added the postscript: "I'm sorry" and then attached the note to the front of the book with a sticking charm. Today was a day for breaking all kinds of promises to himself, apparently - but his use of the word "sorry" was a relatively small one.

Snape pulled his chair forward, knelt on it, and opened the book. His skin immediately felt icy cold, but he didn't bother trying to remedy the matter; the book always had that effect, and no amount of warmth could fix it. Snape began to flip through the pages, searching...

And suddenly Neville was slapping his face, saying "Professor? Professor?" in a terrified voice.

"Stop that," said Snape automatically. He attempted to cuff Neville across the side of the head, but his arm hardly moved off the floor. Snape began to shake violently, his teeth chattering.

"I'll get Madame Pomfrey," said Neville, beginning to stand up.

This time Snape's arm did respond. He grabbed Neville by the front of the robes, and said "Not if you want to live, Longbottom."

"But -" said Neville, "but you're sick! That book, it was - was - It was doing something to you!"

Snape struggled to sit up, but couldn't manage it. "The book - where is it?" he said weakly, flopping back.

Neville slid an arm under Snape's shoulders and lifted him up to a sitting position easily. It occurred to Snape that his little-boy body must weigh almost nothing.

"It's on your desk, Professor. I closed it. Is it cursed?"

"No," said Snape, "but apparently it's hungry."

Snape rubbed a hand across his forehead. It suddenly felt like someone was tattooing their name on his frontal lobe with a knitting needle. "Damn it," he said. "I'm too weak. I never even thought of that. A child can't withstand it."

"What is it?" asked Neville.

Snape put his hands against the cold stone floor and found that he could support himself now. "It's just a book, Longbottom," he said evenly, "but not one meant for children."

Neville turned and stared at the book - and Snape's inpromptu will written on the front of it - for a long moment. Then he turned back to Snape with an expression that Snape had never seen on Neville before: a look of determination.

"It's Dark Magic," the boy said.

"Don't be stupid, Longbottom. Do you really think Dumbledore would permit such a thing in Hogwarts?" said Snape acidly, rolling over and pushing himself to his hands and knees. After a moment, he put a foot under himself and tried to stand up. It didn't quite work; Neville had to grab his arm to keep him from falling on his face.

"So it's all right if I go and tell Dumbledore about it?" said Neville, his voice sharp.

"You'll do no such thing!" said Snape.

"Why not, if it's just a book?"

Snape stared at Neville. "I said, you will do no such thing," he said.

"Or you'll do what?" said Neville, his voice calm and even. "I probably weigh twice what you do right now, and if you're not strong enough to read that book, then you're probably not strong enough to hex me very well either."

Snape stared at Neville. Who expects a sheep to bare its teeth? "I am your Professor," he said. "You will do as I tell you!"

"Or you'll do what?" Neville repeated, his face set and determined. "Put me in detention? Dock my house points? Threaten to have me expelled, or simply make my life as horrible as possible? You do all those things already. That's no threat at all."

"You detestable little shit!" Snape snapped. "How dare you!"

"Just save it, will you?" said Neville wearily. "You haven't got time for this! I know that book contains Dark Magic; I saw what it was doing to you."

Snape gritted his teeth, trying to hold his anger in.

"And I won't tell Dumbledore if you don't want me to," Neville said, "but I'm ditching all my classes so I can help you, and you of all people should know that I can't really afford to do that. I shouldn't be here - but you haven't got much time left, and I don't want you dead. So I'm here. You could at least have the decency not to lie to me."

"You don't want me dead?" said Snape savagely. "Really? Your dear old Potions master who has always taken such a particular interest in you?"

The look that Neville gave Snape made the boy look about twenty years older than he actually was. "You occasionally make me wish that I was dead," said Neville, "but no, I've never wanted you dead. I don't wish anyone in this world dead. Not even You-Know-Who. Not even - the Lestranges."

Snape met Neville's eyes for a moment longer, and then turned and stared at the book on his desk.

"I'm trying to help you, Professor Snape," said Neville. "I'm just asking that you don't lie to me about that book."

Snape continued staring at the book. After a moment, he said quietly, "It is Dark Magic, Longbottom. I thought I remembered a potion from it that resembled the one you made."

Neville was shocked silent for a long moment, and then he said in a horrified voice, "But I couldn't have made a Dark Magic potion by accident, could I have?"

"Possibly," said Snape, shrugging dismissively, "but not a potent one. That requires malice, and you don't appear to have any. I need you to read this book for me, Longbottom."

"What?" yelped Neville. Snape turned back to the boy.

"I'm sure you heard me," he said. "I need you to read this book for me. I can't do it myself - my body and powers are too immature. You're fifteen. You should be able to withstand the book's attempts to feed on you, although only barely. What I'm banking on is that you, in particular, will prove to be resistant to the influence of Dark Magic."

Neville was shaking his head. "I think you should get Professor Dumbledore to help you with this," he said, staring at the book in horror.

"Professor Dumbledore does not know that I own this book, and I do not want him to know!" said Snape. "Longbottom, if you don't wish ill on anyone - anyone at all - then Dark Magic cannot manipulate you! It finds its way under a person's defenses through their hatreds and ambitions. You are not hateful, Longbottom, and I certainly hope you're as unambitious as you appear, because the only thing more intolerable than an idiot is an ambitious idiot - just look at Percy Weasley. You will read that book for me, Longbottom."

Neville reddened, and said sharply, "Not if I don't want to. Why do you own this? Where did it come from?"

Snape paused; this was a very inconvenient question, but he very inconveniently needed Neville's help. "I really don't want to answer that, Neville," he said.

Neville blinked. Snape was hoping that the surprise, and implied intimacy, of using the boy's first name might make enough of an impression on him that Neville would relent, and not force him to answer the question.

Unfortunately, Neville was showing uncharacteristic amounts of backbone today. "No," said the boy. "If you're going to ask me to do something this dangerous for you, I think I have the right to ask questions. My trouble in Potions class is that I don't really understand what I'm doing - but I need to understand what I'm getting into here, because this is more dangerous than Potions class by a Quidditch field. Where did you get that book from?"

Snape had always prided himself on being fearless, but that didn't mean that some things weren't hard to force himself to do. It took a long time for him to finally say "I got it from the Dark Lord."

Neville went white, and his pupils dilated. Snape stared at the boy's expression of terror, and thought, 'Blast it. I've frightened him too badly. He's scared that...'

And realising what Neville was scared of made the remedy for his terror clear - but this wasn't going to be any easier an admission than his previous one.

"I was a Death Eater, Neville," said Snape. "Was. I am not one now. And yes; Dumbledore knows about it."

"You - you're not -" said Neville, still pale with fear. Snape pulled up his sleeve, and stared bitterly down at the mark that he couldn't erase. It was pale, and distorted on his child's arm, but it was still clearly the Dark Mark. Snape had looked at it that morning, and thought how unfair it was that his body could regress to infanthood without erasing any of his past sins.

Snape extended his arm to show Neville the mark. "If you think I'm evil and vile now, Longbottom, I assure you that I'm a loving pussycat compared to the man I once was. I have, in the past, murdered on purpose, or on a whim. I have tortured for fun, and to obey orders. But I also would rather kill myself than ever become that man again. I turned my allegience away from the Dark Lord - actually - about the time you were born. I acted as Dumbledore's spy for more than a year before the Dark Lord fell. I had nothing to do with what happened to your parents, Neville; I didn't even know that was going to happen."

Neville was silent for a very long time. Snape finally couldn't stand it anymore, and said, "Swear that you will tell no one about this, Longbottom."

Neville stared at the floor, then said, "Dumbledore?"

"Yes," said Snape. "You can talk to Dumbledore about it if you wish. He will confirm what I have said. But do not tell him about the book. He would - be very disappointed in me."

"Do you use that book?" said Neville.

"No," said Snape. "I haven't even touched it in fifteen years. I - it still has power over me, and I don't ever want to become the man I was again." Snape frowned at the book. "But I'm becoming the boy I was, and will die sometime tomorrow, as a premature infant struggling to make my lungs work, if I don't find a way to reproduce your potion. I think this book is my last hope, Longbottom."

Neville said nothing more, but turned slowly, sat down at Snape's desk, and hesitantly opened the brown leather book.