"All right," said Hermione, pausing outside a disused classroom. "Before we get go to the hospital wing, I think we should test my theory. If you'll give me Scabbers, I will turn around, then one of you - don't tell me who, and don't say anything - go in the classroom and pick two corners of the room randomly, walk to each, then come back. When you're done, I'll go in with Scabbers and test the spell - if he can tell which corners you went to, and lead me back to the right one of you, then we're in good shape." The Gryffindor boys stared at her in confusion.

"But...why don't we just test it in the actual place, save some time and trouble?" asked Ron. Hermione shook her head.

"If it turns out not to be practical, there's no point in even trying it and risking getting in trouble with Madam Wainscott or anyone else. Also, this way we can check the answer, because you two will know it, whereas in the hospital wing, we couldn't be sure it wasn't just a guess or something?" Also, I needed to prep the room first, and that would've required an additional pretense to get Madam Wainscott out, Hermione added, silently. The boys looked at each other.

"Makes sense to me," said Harry. Ron shrugged, and handed over the rat - Hermione steeled herself carefully to avoid showing her revulsion, though again wondered if it might've been more in character for her to be uneasy about handling a rat.

She also made a point of standing so that she couldn't see what the boys were doing, but angled slightly so that the rat - if he were so inclined - could in fact spy on them. Better to give him every opportunity to cheat now, to feel as smug and confident as possible in whatever he decided to do.

There were quiet noises behind her as the boys exchanged gestures to work out who would go in, followed by the sound of the door opening and closing, then doing so again after a brief delay. At the second door closing, Hermione turned back to face Ron and Harry.

"Ok, just wait here. It might take a little while, since I'm going to be very careful, so please be patient? Oh, here," she added as if it was an afterthought, pulling a quill and a scrap of paper out of her bag and handing them to Harry, "once I've gone in, write down which of you went inside, and which corners you went to - it's important in science to document everything as you're doing it." Harry nodded, though he glanced at Ron, which probably meant Ron had gone into the room, but then the blind nature of the experiment wasn't actually the point, after all. That taken care of, Hermione entered the room and closed the door behind her.

"Can I really trust them to wait, though?" Hermione asked herself quietly, deliberately forcing uncertainty into her voice - though this was not all that hard, considering. She withdrew her wand from her bag and aimed it at the door. "Colloportus," she said, making a tied-knot gesture with the wand tip. Throughout this process, she did not yet put Scabbers down. An Animagus transformation - indeed Transfiguration in general - conserved the location of the center of mass unless the accommodation of the process otherwise shifted it. But she obviously couldn't support the weight of an adult man with one hand, which meant if he reverted now, he'd probably end up falling at least 30 centimetres or so to the floor, and Hermione was hoping he'd wait rather than risk turning an ankle or something. Either her guess was accurate, or his plans didn't suit changing yet, because the rat remained quiescent during this process.

When making her preparations, Hermione had picked the room partially due to its proximity to the Gryffindor common room, but also because it was a fully interior room and did not have any windows. She'd also carefully checked along the base of the walls around the room's perimeter for any chinks or holes a rat might squeeze through, and found none - thus the door was the only way in or out. She knew that if things went horribly wrong and the murderer somehow escaped what she'd planned - and had a wand - her simple Locking Charm wouldn't hold, but it would slow him at least a moment. While turning away from the door, she surreptitiously kicked what appeared to be an oddly-shaped collection of wood fragments about three inches high - it skittered on the stone floor and ended up roughly centered on the doorway.

The classroom only held a handful of desks and no table, so her path to the center of the room was largely unobstructed. Hermione glanced around, making sure everything was in place, took a breath to steady herself, then started Step 4. She couldn't help tensing as she set the rat down on the floor - this was his first good chance to try something - but for the moment he seemed content to play his part as she was playing hers.

"I'll have to go over the spell a few more times," she said, "I'm sure Ron won't mind if you have some biscuits while you're waiting…" She removed a pair of Bourbon creams from her bag, setting them down before the rat, then reached back in for Practical Household Magic, all the time not letting go of her wand. Ostensibly this was to review the Supersensory Charm, but in actuality it was just a prop for a brief delay. Hermione watched carefully over the top edge of the book to see if the rat seemed at all suspicious, but he had begun devouring the chocolate-flavoured biscuits without hesitation.

In a little more than two minutes, he'd finished eating and cleaning his face and paws, and seeing Hermione still apparently muttering over her book, settled down patiently to nap. She waited as long as she dared, but if she waited too long most of her planning would end up wasted, and plus the longer she waited the more tense she became - she wasn't sure she'd have the nerve to go through with it. Hermione took a few more breaths that she'd intended to be calming, but had little effect on her churning stomach. Her hand shook a little as she tipped her wand down past the edge of the book, but she held her breath, waited for it to steady...waited…

"Emméno," she said, with a double-flick of her wand, aiming the (non-Permanent) Sticking Charm at the rat's left forepaw, currently resting against the stone floor, his other paw crossed over it and his head atop both.

At once, the rat awoke, and - as she'd hoped - instinctively planted its other paws for leverage to try to free the first. Hermione immediately cast another Sticking Charm at the other forepaw, then each of wthe two rear paws for good measure, ignoring the rat's increasingly frantic squeaking. Hermione put the book back into her bag and kept her wand trained on her captive.

"You needn't bother - without a wand in hand, I'm pretty sure you couldn't get loose from even one of those, let alone four. Also, I know you're not a natural rat, and that you murdered Madam Pomfrey, probably because she discovered that too." Hermione tried to deliver this declaration in a tone of quiet confidence, but she found by the end her voice was a bit shaky. Her wand, at least, stayed steady enough, if not quite as steady as the proverbial rock. As for the rat, he had frozen, looking up at her by the start of the second sentence. By the end...the rat's form had begun shifting, growing. Hermione readied herself just in case it turned out her tests hadn't been rigorous enough, or the results couldn't be extended to an Animagus transformation...

But they had, and could, and she relaxed - slightly. The rat had become an adult man. It was hard to tell in his current posture, but it seemed like he was on the short side, balding, in casual robes that had deteriorated to the point that they were little more than rags. Even if he was short for an adult, he was decidedly rounded, and probably outweighed Hermione by at least a factor of three. His slightly beady eyes rolled wildly, his face a mixture of outrage and fear - but much more of the latter.

As Hermione had tested, with the help of a few Engorgement and Shrinking Charms, a Sticking Charm retained its enchantment even under shifts in size, and thus his entire palms were still affixed quite firmly to the stone floor, rather than tiny rat-paw-sized patches of them. His shoes were not - Hermione supposed because whatever kept his clothing suspended in the transformation didn't apply to the accommodation of the Sticking Charm, so the charms on his feet had dissipated being otherwise separated from the floor - or perhaps were simply holding his shoes on? And though the centers of the charms on his hands had shifted, each area had to continue to overlap the original area defined by the spell, so his hands were now touching, thumb-to-thumb. Unable to support himself in that position, he'd toppled forward, his legs splaying out, elbows bent awkwardly to avoid putting uncomfortable pressure on his wrists. He looked up at Hermione in a panic, eyes wild.

"No, no, no...you have it all wrong! I'm a marked man, I'm hunted, I had to hide...but I didn't kill the Healer, I didn't!" Hermione wasn't inclined to simply take his word for it, but he did seem truly terrified.

"You were there...the staff checked, and no one else could've done it," she pointed out, reaching into her bag with one hand while the other kept her wand on him. The man shook his head frantically.

"The staff checked...was Snape one of them?" Hermione frowned, and the man's expression became desperately triumphant. "He's always been one for lying and sneaking and secrets...I saw him kill Pomfrey with my own eyes...I only just managed to open that cage and escape before he set up that subterfuge with the salamander blood and the quills, protected by a Bubble-Head Charm the whole time! When the other staff investigated, he must've interfered...subtly, carefully...and covered his tracks!"

While Hermione tried to wrap her head around this accusation, another part of her automatically continued the plan, since either way, there was no good reason not to. She did not direct her wand away from her prisoner, but instead brought her other hand around in front of it just long enough for her Finite to catch the tiny object she held, which - no longer under the influence of seven stacked Shrinking Charms - agreeably ballooned outward until it was the normal-sized magical camera she'd borrowed from Penelope Clearwater. As much as she would have liked to quip 'Watch the birdie…' or something, surprise was paramount in the Plan as she didn't want him to have any chance to transform back into a rat at this point. So while the man was still trying to grasp what he was seeing, she centered him in the viewfinder and poked the shutter button with the tip of her wand. He blinked and sputtered from the large flash, looking even more desperate if anything. Hermione set down the camera carefully, keeping her eyes and wand on him.

"What motive could Professor Snape possibly have for killing Madam Pomfrey?" Hermione asked, though there was not as much skepticism in her voice as there might have been. She now rather regretted not having had Harry explain precisely what he believed about the Potions Professor. Before the man could respond, a loud pounding began on the door, and muffled voices. Hermione simply sighed, while her prisoner startled violently, wincing at the pain this produced in his hands.

"Oh, Merlin, who's that?!" he cried. Hermione shook her head.

"That is the sound of someone who - presumably because they are Gryffindors, or possibly because they are boys - upon hearing a Reminder Charm on a quill tell them there is an emergency and to find whoever of Professors McGonagall, Flitwick, Quirrell or Dumbledore is nearest and bring them here as fast as they can, rather than doing that, have instead elected to shout and also pound pointlessly on the door that I prudently took the precaution of sealing. Though the latter was mostly for you," she added dryly. "Professor Snape?" she prompted, after a moment. The man blinked.

"He's a secret Death Eater, has been for years! Pomfrey must have suspected something about me after all those tests she did, and he somehow learned of it first - I'm marked, I tell you, I was in the Order of the Phoenix, fought against the Dark Lord...Snape came to do unspeakable things to me, but first he had to eliminate the witness…" Hermione stared. That was ridiculous, Professor Snape was...well, a Professor. Teachers didn't go around being evil and murdering people, they just didn't. And if you were secretly evil, why on Earth would you go around deliberately trying to look evil? Professor Snape, like anyone, probably had various problems, but being stupid didn't appear to be one of them. And yet, Harry had learned something… Hermione glanced at the door, but by now the pounding had stopped. Looking back, she found the man had also noticed, and his panic had increased.

"Do you have any evidence of that, other than your claim that he killed Madam Pomfrey? And if you knew he was evil, why didn't you just tell Dumbledore earlier? You've been living with the Weaselys - as a rat - for years!"

"I...didn't have evidence! If I'd accused him, Snape would've wiggled out of it somehow, and then some odorless, tasteless potion would've found its way into my soup, and I'd have tragically choked to death or something!"

"So just tell Professor Dumbledore what you told me, surely-"

"Snape's muddied the waters, I told you! Unless...you could let me go, let me be a rat again, use your Charm, and I'm sure I can find Snape's trail. But even with him in Azkaban, the Dark Lord still has other secret supporters, I'd never be safe...just don't tell anyone, let me live as a rat, please, I'm fine with it, I'm a good rat…" Hermione's confidence was wavering, but her sense of propriety just couldn't let this last one go.

"Look, you can't just carry on sleeping in children's beds as a rat, it's just...you just can't, okay?" She shuddered. "And besides, I, ah, don't actually think the Supersensory Charm will work that way...that was a sort of trap. Just wait, the Headmaster is a really amazing wizard, I'm sure he can think of a way to keep you safe…" The man, who'd been staring at her throughout, began to thrash, his face twisted in frustration and terror, eyes rolling wildly, wincing each time he strained to free his hands - one of which, Hermione noted, was missing a finger. Suddenly he slumped into a sort of dejected squat, his chin falling to his chest. "I'm really sorry," Hermione said, feeling a lot less good about the whole thing than she'd expected to, "I can't release you, but if you're telling the truth, everything will work out...somehow…"

Could Snape have actually done it? Hermione still didn't know what spells the staff had used to investigate, maybe they could be fooled, particularly if you knew in advance what spells were likely to be tried, and were actually present there to make certain. But could he have done it right under the Headmaster's nose? Then again, while Professor Dumbledore - at minimum - had been sharp enough to suspect foul play, he hadn't managed to find Scabbers or Professor Snape, so maybe he wasn't infallible. And that bit about muddying the waters wasn't hard to imagine, given how easily her future self had done it to her. But something else had occurred to her.

"If you were just running for your life, why did you steal Lavender's wand? And, more importantly, why run back to Ron's room, if you say Professor Snape knew who you were, wouldn't he just-" Hermione's question was interrupted by a terrible cry of mingled exertion and pain as the man lunged upwards from his squat with desperate strength. His scream mixed with a nightmarishly wet sound as all the skin from both of his palms tore free, gory handprints left behind on the stone. He staggered back a step, off balance from the sudden lack of resistance, his face contorted in pain.

Hermione had tried to think of ways the Plan could go wrong at each stage. She'd moved all the furniture away from the center of the room (and put some of it to other use, besides) so he couldn't reach anything with his feet, or with a free hand in the event she'd only been able to get one stuck before he transformed. But this hadn't occurred to her at all, and even though she still had contingencies that might help, she simply wasn't emotionally prepared for the sight of a man mutilating himself to get free of spells she'd cast. And she wasn't even sure he was guilty anymore, he might just be so terrified he'd lost his reason. She froze in indecision.

One of his bloody hands reached into his tattered robes and pulled out Lavender's wand, face twisting as he tightened his flayed hand around it, pointed it at her. A part of her noted that this still didn't prove anything, but the rest of her decided it still looked pretty bad, and her hesitation broke.

"Expelliarmus!" she cried, giving her wand the appropriate diagonal flick. But the man slashed his wand downward, causing a bright flash as her spell was parried. He aimed his wand back at her, but Hermione had planned this sequence in advance and was already dropping onto her stomach, her own wand extended. His wordless spell finished first, but sailed over her and struck the wall behind. But he was still fast and experienced, and was able to sweep his wand down in another parry as Hermione shouted, "Illubrico!"

However, the strategy she'd worked out had called for her to - just in case he already had a Shield up - aim this spell at the floor, and since the Lubricating Charm did not form a visible projectile, he was unable to adjust his parry to block the spell's unexpected trajectory. The stone became nearly frictionless, and the man's feet shot out from under him, dropping him heavily onto his back.

At this point, Hermione hesitated - she was encouraged that her spell combination was actually working, but the next part called for her to manually trigger a fail-safe that ought to disable him. Except during her planning, she'd presumed that if things reached this point she would be in a life-or-death struggle and basically anything would be justified - including the fail-safe, which might cause serious injury or even death - whereas now she was uncertain enough to question that. But her instincts said she had no choice - and as long as he wasn't killed outright, if he was innocent, Madam Wainscott and the Professors ought to be able to set everything right.

But the brief hesitation to weigh the moral considerations had been costly, and even as she began to point her wand upward, her opponent had recovered from his fall and launched his own spell. Hermione tried to dodge, but she was too slow, and before she even got two syllables out, her wand was sailing out of her hand to clatter into a corner of the room. I should've thought of that, tied a safety strap to it or something, but I was expecting Curses, not a Disarming Charm, maybe he really isn't a horrible murderer after-

"Crucio!" snarled the man, struggling to his feet. Blood spattered the stone beneath him, scattered drips from his free hand mixing with staccato spurts between the fingers of the other, squeezed out by the pressure of his grip on the wand.

Thought vanished as Hermione's world became pain. It was like her blood was on fire, or like her blood had been Transfigured to hydrofluoric acid, or something even more gruesome, except she couldn't really form these concepts, only feel them - there was no room for anything but the searing, hateful agony. And then it was suddenly gone, leaving her twitching and panting on the stone floor - blood no longer burning, but muscles still aching from their involuntary contractions, her cheeks wet with tears, one of her fingernails chipped from clawing at the hard surface beneath her.

"Tell me what you know about me, what you've told!" screeched the man. "Tell me, so I can fix it…" Murderer or not, he was clearly unhinged at this point, and Hermione was terrified - she was pretty sure she'd do anything not to feel that pain again. But she still only answered the second part of his mad demands.

"Y-you...were there...only w-what I...told Ron and Harry," she stammered out, between gasping sobs.

"Who else?! You didn't plan this trap yourself, who is helping you?!"

Hermione's mind cast about frantically for what he might want to hear. She wondered if he'd believe her if she told the whole truth...maybe that'd be enough time for a Professor to actually get here, since it seemed like the man's own heart-pounding fear - and maybe the pain in his hands - was interfering with what was supposed to have been her second fail-safe. And the Cruciatus Curse hadn't triggered the first...maybe that was why it could eventually drive a victim insane, you never lost consciousness from its effects, no matter how much you might want to? He raised the wand again, and Hermione's train of thought vanished as she immediately began to speak as fast as she could form the words, her brain barely connected to her mouth.

"No one, honestly, I tried to talk to Dumbledore but I couldn't get into his office or he was out and I asked the Defence Professor for advice but it was all hypothetical and they all think I've been hexed so I needed real proof which is why I borrowed the camera, but the trap I just thought about and I've always been quite good at thinking, but now I'm rather suspecting I'm not smart at all and maybe I should have been in Gryffindor, because I can't imagine how I expected for a second any of this would-"

"Dissocio," he interrupted, swishing Lavender's wand downward into a alternating flick at the end. Hermione gasped - recognizing a Disassembly Spell, and suddenly horrified at the thought of what it might do to a human body - but the spell was not aimed at her. Instead the camera turned into an exploded diagram of itself, all its individual parts separating and hanging in the air for a moment, then dropping gently to the floor. "Accio proof," he continued, waving the wand vaguely at the scattering of camera parts, and the film agreeably soared towards his free hand, but he recognized the problem with this and an additional flick sent the roll to the floor in front of him before it could contact his bloody, fleshless palm. Another flick and the mottled appearance of the exposed film changed to a uniform brown-black. A final swirling motion sent the film and all the camera parts back together, each fitting neatly into its proper place.

While the man was carefully destroying her evidence, Hermione shakily stood up. Her wand was several yards away, and the only other ways of deliberately triggering her fail-safe she could think of seemed both unwise and unreliable. Though if it appeared he was about to use the Cruciatus on her again, she thought she might just go ahead and try one anyway. In the interim, she tried edging towards her wand as subtly as she could. She'd only made it about halfway when his attention turned back to her, whereupon she froze and tried to give the impression she was terrified into abject submission - a feat which did not require much acting ability, under the circumstances.

"Accio wand," he said, aiming his own wand to the side, but keeping his eyes on her. Hermione's wand obediently leaped into the air and landed neatly in his free hand. He grunted at the pain this caused, but maintained his grip on it. "Trying to be clever? With me? I can always see what people want to hide..." The little man gave a hollow laugh, and Hermione couldn't keep disappointment from touching her features. He tucked Lavender's wand into his robes, and switched Hermione's to his right hand.

"What...what are you going to do now?" she asked, her curiosity only barely edging out her fear at hearing the answer.

"No time to stage a convincing death scene for you, it'll have to be a Memory Charm," he mused.

"So you did do it. But...if you can do Memory Charms, why did you kill Madam Pomfrey in the first place?" Hermione asked, aghast.

"I'm not very good at them," he said, with a shrug and an elaborate yawn. Hermione's heart briefly swelled with hope, but even if the Liquid Sheep she'd dosed the biscuits with was finally starting to kick in, it was taking forever...the dose must've been diluted within his greater body mass. But if he kept talking long enough… "I don't know enough Potions to pass off that kind of mental damage as an accident. But with that convenient Hex as an excuse, I can probably get you shipped off to St. Mungo's permanently, convinced of something ridiculous - say, that Grindelwald had escaped and had for some reason transfigured himself into a desk somewhere in Hogwarts…later, when I've had enough time to work something out and suspicion to die down, I can arrange a tragic accident for you too. " He raised her wand.

"Wait!" interrupted Hermione, desperately. "If you're going to Obliviate me anyway, can you explain why you were really hiding as a rat first?"

"What would the point in that be?"

"I'm a Ravenclaw. If I have a choice between not-knowing and knowing...even temporarily...I'll choose knowing." For a moment, it looked as if he actually empathized with her, but the rat-faced man shook his head.

"I recognize stalling when I see it, and reinforcements could arrive any minute."

Hermione dove to one side as he opened his mouth again. She didn't have much hope of actually dodging the spell he was about to cast, so she also flung her arms backwards, piking forward, trying to hit the stone floor headfirst as hard as she could manage and if she was very lucky, triggering the other fail-safe before-

"Petrificus Totalus!" The spell might have helped her, preventing an instinctive flinch, except that it also forced her rail-straight, so the impact was distributed more evenly across her entire body instead of just her forehead as she'd intended. It still hurt when her nose hit the floor, but not as much as the realization that she hadn't planned carefully enough, she hadn't read enough...she was going to be Obliviated again, probably be committed, and then - at some point - die.

It wasn't supposed to have been like this. Probably all kinds of people thought something like that in their final moments of clarity before some ignominious end, but Hermione suspected she was unique in actually having fairly strong evidence on which to base that assertion. If this was how Time really worked, this disproportionate ruination of everything, she didn't think much of how the Universe was arranged. It was petty and nonsensical and frankly, someone ought to put Time in its place.

She really hoped someone would, even if it obviously wasn't going to be her.

"Obliviate."

There was a terrible wrenching disorientation.