I flip through the book on introductory alchemy as I sit in the Gryffindor common room. As the season has slowly shifted to spring, people have started spending less time in the common room in favour of the grounds. Frankly, I'm glad. It means there are less people around when I'm trying to get my work done.

I still don't know why Tam thought that the best way to introduce me to the principles of alchemy was to read through the bland introduction of a century old book on the advanced principles of the field.

The modern books on alchemy are much easier to understand. Not only is their language less dated, but they draw on advancements made to the periodic table in recent years, making it much more understandable for anyone muggle raised, such as myself.

The simplest forms of alchemy involve the transition of pure elements into other pure elements. Transition and rare earth elements required the Philosopher's Stone, but anything else was fair game.

This was why we had a chunk of raw graphite sitting on the table in front of us.

Ready?

'Yeah, I think so.'

Tam theorised that since performing transmutation required a conscious focus on the material and its principles, then having both of us focus on the process would increase its efficiency. Essentially, we'd be using that pesky soul bleed to our advantage.

Tam takes control of my body and presses my wand to the graphite. From there, we both begin focusing on the carbon and its structure, slowly changing the structure without changing the components. This process continues until the carbon stops accepting more magic. She opens my eyes, and sitting on the table in front of us is an uncut diamond.

'Wow.'

It actually worked.

'And now we have a diamond.'

Yup. Pity that it's worthless.

'Er… it is?'

Harry, we were able to make a jewellery grade diamond with only a few months worth of experience. Anyone with a rudimentary understanding of alchemy can make diamonds. Diamonds have little intrinsic value in the wizarding world beyond their properties as a material.

I briefly ponder flooding the muggle market with diamonds to tank their value, making all of Aunt Petunia's diamond jewellery worthless, before deciding that it would be too much work for too little gain. If I'm going to get petty revenge on Petunia, then I'd want it to be the sort of slow, inescapable thing that would lead to her having a mental breakdown. I mentally chuckle at the thought.

Now, let's try something a little more elaborate. Ready?

Tam presses my wand to the diamond, and we set about inducing another change. This time, we keep the structure the same while altering the material. Much like last time, we continue the process until the material stops accepting new magic. She opens my eyes again, and the diamond has been replaced by an identically shaped chunk of dark grey material with a blue lustre.

"Fancy stuff, Harry." A voice says from over my shoulder. "How long have you known alchemy?"

Tam jumps when Katie first starts talking, and I take the chance to take back control of my body.

"I've been practicing for around ten minutes now, if you must know." I reply as calmly as I can manage. "Is there a reason you decided to announce your presence by speaking right into my ear?"

Katie smirked at me. "I like watching you jump. It's adorable how skittish you are."

I sigh and pinch my brow.

Katie sighs back. "Fine then, don't take the compliment. So, this is silicon, right? It's not bad, but I thought the diamond was prettier."

"It's just a carbon crystal. It's not that special aside from its durability."

She rolls her eyes at me. "That's such a boy thing to say."

Hey!

That conversation is interrupted as Angelina enters the common room. "What the hell is up with Lupin lately? Two days ago he interrupted potions class and asked if we'd seen a rat. I thought Snape was going to murder him at the time. Then, just now, he interrupted my career meeting with McGonagall to ask about the same thing!"

Katie raised an eyebrow. "I guess you could say he's in something of a rat race. He might even be having what'd you'd call a ratty day. Eh? Ehhhh?"

"Shut the fuck up, Katie." Angelina snaps.

Katie sighs and shrugs her shoulders. "No one appreciates my genius."

"I have no idea what's up with Lupin." I say, cutting off their squabble. "He's done the same thing to me five times over the past two weeks. At first I thought he was trying to track down something that Fred and George set loose, but now I'm not so sure."

"Is this how we lose our next defence professor?" Katie asks. "We watch him go insane trying to track down a rat?"

I snicker at the thought. "Wouldn't that be ironic. We have a werewolf for a professor and he loses his job through something completely unrelated."

"Lupin's a werewolf!?" Angelina exclaims.

Crap, I probably wasn't supposed to say that.

Katie rolls her eyes. "Duh, of course he is. He's 'mysteriously sick' every full moon, and all of Snape's substitute lessons are about how to identify and defend against werewolves. To top it off, Snape was brewing Wolfsbane during one of my detentions with him. You'd have to be an idiot not to put the pieces together."

Okay, so apparently it wasn't a huge secret. Still I feel stupid for not figuring it out until after I'd performed legilimency on him. The evidence really was right in front of me. I hope I'm not missing anything else important…

"But he's a werewolf!" Angelina protests. "He's dangerous!"

"You know what else he is?" Katie retorts. "Competent. Angelina, I swear to God, if you get the first competent DADA teacher I have had in four years fired, I will never forgive you."

"He turns into a ravenous monster once a month!"

"So do you! The last time you were on your menses, you snuck into my room and stole the last box of chocolates that I'd seduced McLaggen into buying for me! Them, to add insult to injury, you told me that it was for the good of my waistline! As if I'm the one who needs to watch what I eat when you've been packing on the pounds!"

"I have not!"

"Oh yeah?" Katie steps forward and pinches Angelina's midriff. "What's all this then? These baggy robes may hide the truth, but I've seen your developing potbelly in the Quidditch showers."

Well that certainly puts an image in my mind.

You know, I had a train of thought going, and I feel like I was almost onto something before I was interrupted.

'That's nice.'

Harry, I try not to ask more of you than I need to, but can you please stop picturing your teammates fondling each other's naked bodies in the shower?

'…I don't think I can.'

Harry, I am feeling anatomical sensations from you that I'd really rather not feel. Please, for the love of gods, do something about it!

"If you'll excuse me, ladies." I say as I stand up. "I've got some business in the loo that I need to take care of."

That is not what I had in mind!

Angelina's eyes widen in shock, but Katie just smirks.

"Looks like you're not the only one I managed to get a rise out of, Angie."

"KATIE, IF YOU DON'T SHUT THE FUCK UP RIGHT NOW, I SWEAR TO MERLIN I'LL-!"

I feel dirty.

'You weren't at all involved in the process. You were occluded from me the entire time.'

I can feel your lingering euphoria and I know where it came from.

'I mean… It's not the first time I've, uh…'

There was plausible deniability before! This time I know exactly what you were doing!

'I'm… sorry? I don't know what to tell you.'

How about you not tell me when you're doing it in the future. Please.

'Um… Look, this is really awkward. Let's just change the subject.'

Please do.

'So… you said you thought you were onto something earlier? Any idea what it was?'

No, I… I feel like we're missing something. Like there's something that doesn't match up and I can't put my finger on what it was.

'Do you remember what it was about?'

Not in the slightest. Your mental imagery saw to that.

'Sorry.'

It's fine. I get that you're at… that age, but please try not to let it happen more than necessary.

'Um… sure.'

…

'…This just got awkward again, didn't it?'

Yeah, it did.

'So… why don't you show me another one of your memories? You still haven't explained what went wrong when you made your horcrux.'

Ugh, fine. Anything would be better than this. Let me know when you're ready.

I leave the bathroom and sit on my bed in the empty dorm room. I debate putting up some basic protections around my bed, but decided against it. It's not like anyone else is going to be around anytime soon. I flick my wand to shut the curtains and cross my legs as I sit down.

'So, what's it going to be this time?'

Tessie being extremely helpful.

'Well, that does sound inter-'

Tam doesn't give me a chance to finish that thought.

My tongue clicks in irritation as I slam another useless book shut. The librarian gives me a harsh gaze, but I'm too irritated to care. Ten books on Herpo the Foul, including those from the restricted section, and no details on what he did to prolong his life beyond "dark magic". One of the books speculated that it was soul magic of some form, though I was hesitant to take such speculation at face value. Even then, soul magic is a very broad and very illegal field. Just obtaining the resources on soul magic to recreate his discovery would put me on a huge number of Ministry watchlists.

Which basically puts me back at square one. Unless I can obtain firsthand resources on what Herpo did without raising any alarms, then I'm stuck.

I dump the books on the return cart and storm back to my table. My annoyance peaks as I find several newcomers seated there idly gossiping as they work on their essays. I scowl as I hastily shove all of my things into my bag and storm off elsewhere. I can't even find a place to work without being bothered by the inane rabble. If only there was a place I could study without being bothered by anyone…

As soon as I think that thought, I realise that I do have such a location… sort of. The Chamber of Secrets is certainly solitary. I don't know if it would make the best study location, but it wouldn't hurt to try.

At least the entrance is discreet. No one would be suspicious of a student using the bathroom. I imagine sneaking in here would be much harder if I was a bloke, but thankfully, that's not a problem.

A hissed "open" reveals the staircase, and I begin the trek down the stairs to the Chamber.

By the time I actually reach the Chamber, I'm vowing to have it cleaned the next time I have an opportunity. It's so uncomfortably damp. I must have messed up the Impervious Charm on my shoes, as it gave out halfway to the Chamber. It ends up taking four drying charms to remove all the water from my socks and shoes once I'm no longer forced to wade through the water.

"§Speak to me, Slytherin, greatest of the Hogwarts four and all that jazz.§" I grumble to the statue. I really hope I don't need to buy a new pair of shoes. I don't know if I can afford them.

"§I see that you're back, child.§" Tessie greets me. "§Have you come to enjoy some sanctuary?§"

"§Among other things…§" I smear some blood on the wall to open the passage to the Inner sanctum and sit down at the table. I begin looking over my assignments. "§And feel free to call me Tamelyn.§"

"§That's a silly name.§"

I roll my eyes. "§Well, it wasn't supposed to be my name, but my mother was dying and the matrons at the orphanage weren't familiar with Scottish Ballads, so Tamelyn it is.§"

Tessie gives a hissing laugh and coils up in the corner. I start rooting through my book bag for study materials.

"Let's see… Charms is done, Potions is done, History is… hmmm… §Say, Tessie, I don't suppose you're familiar with Herpo the Foul, are you?§"

"§He was the progenitor of my kind, yes? Salazar studied his work extensively as the basis for imbuing himself with the essence of serpenthood.§"

"§Are there any books here about his… pursuit of immortality? I've been trying to follow in his footsteps, but records on the subject have been lacking.§"

"§Salazar had no interest in becoming eternal, but I believe that the methods were mentioned in one of the books here. Check the rightmost book on the second shelf from the bottom.§"

I move over to the shelf. The book in question is bound in an unusual leather and looks far older than the others. I suppose that makes sense given that Herpo predates Salazar by some time. Still, I place it gently on the table and open it.

It's written in Greek. I don't know what I expected.

"Shit. §I don't suppose you can read this?§" I plead.

"§I saw no need to learn how to read the writings of humans.§" She hums contently. "§But I believe that Salazar left some loose pages with commentary in the book after he finished.§"

I start gently flipping through the pages. Indeed, it seems Salazar did leave some commentary lying around, thankfully in parsel. It would have been just as inconvenient to have to translate Old English.

Let's see. Basilisk breeding, Basilisk venom and its properties… I spend the better part of an hour flipping through the book. Salazar was very detailed in documenting his process. Still, I don't find anything about immortality until I reach the end.

Horcrux.

That's what it's called.

Salazar didn't have much to say on the contents of this part of the book, being apparently wary of the magic it described. Still, he translated the name. I check the Greek writings on the page to check the original term. The original term appears to be "πεμπτουσια", which means… essence, I think? Something about essence. Horcrux must be the translation, though I can't imagine how they came up with such a term…

Still, horcrux. That's the secret to immortality that I seek.

I don't have any information on what they actually are, but I at least have a term to search for now. In fact…

"§Did Salazar mention how he found this grimoire?§" I ask Tessie

"§I believe it came up in one of his journals.§" She replies. "§I didn't pay much mind to his writings, though. I was more focused on finding prey to feed my growth at the time.§"

Very typical for a snake, but still. I grab several of Salazar's personal journals and begin testing out the spell I just finished designing. I place my wand on the cover of the book and then…

"Scriptinvenio §horcrux§."

Nothing happens

So that means that either the spell doesn't work, the spell doesn't work for searching parseltongue phrases, or that this book doesn't contain any references to horcruxes.

I try it several more times as I work my way through the journals, until the fifth one gets a match. Several of the pages around a certain section begin glowing chartreuse, and in my eagerness to check them I nearly forget that I'm handling historical texts. Reason wins out and I carefully open the books to the highlighted part.

The previous owner of the Grimoire of Herpo the Foul has continued to be a thorn in my side. I spared him as an act of mercy, an act that he has not seen fit to repay. He has begun circulating tomes detailing the process of creating the abominations known as "horcruxes". The other Founders and I have been working hard to destroy these cursed tomes wherever they pop up, but we can never be sure that some aren't slipping through the cracks. I fear that if we do not act soon, we shall have another tyrant on our hands, worsening the already poor conditions between magicals and mudbloods.

I flip ahead a few pages.

More of the blasted tomes appeared in Hogsmeade. How exactly such materials were able to get through the protections granted by Hogwarts, we have no idea. Rowena is trying to improve the protections to make sure that no further copies of Dividing the Soul enter our domain.

That's it. Dividing the Soul is a book that details the process required to create a horcrux. The Founders were obviously trying to destroy all of the remaining copies, but based on their apparent difficulties, I doubt they succeeded.

"§I believe that I have found exactly what I need, Tessie.§" I say with a grin. I'm sure that finding the book in question will be a challenge in its own right, but at least I now know my next step.

"§Good. Do stay a while. I like the company.§"

I stifle a giggle. "§I'll make sure to come down here when I can.§"

"§Good. Bring beef if you do. It's been so long since I've had beef.§"

"§I'll keep that in mind.§"

I push myself upright in my mindspace. "Tam, how many more of these memories are we going to have to go through to get to the important details?"

"I am providing context." She replies levelly.

"I'm not denying that the context is nice, but I really feel like you're putting off showing me the important memory for a reason."

"That's none of your business."

"The hell it isn't!" I yell. "I've had a horcrux in my skull for the past twelve years, and now you're here on top of that! I'd say I have every right to know what exactly happened when you created, well, yourself! Fuckup or not, this is critical information!"

"Fine!" She yells back. "Yes, I did fuck up when I created myself. Quite frankly, I wouldn't be surprised if that fuckup is the whole reason we're in this mess in the first place! But I don't like admitting to my failures and I hate reliving them even more! So, for the time being, you'll have to deal with me pacing myself!"

I sigh and flop backwards as the anger leaves me. "Fine. Fine…"

Tam also sighs and leans against a wall, arms crossed.

Dammit, this just got awkward again, albeit in a completely different way than before.

"So, what was that about how you weren't supposed to be named Tamelyn?" I ask, changing the subject.

"My mother wanted to name me 'Tom Marvolo Riddle', after my father and her father." She shudders at the thought. "Thank gods that never came to pass, though not for a lack of trying. The Nurses refused her attempts to name a girl 'Tom'. She then tried to have me named 'Tam Lin Merope Riddle'. Tam Lin was a character in a Scottish ballad of the same name."

"And the nurses mistook it for the name Tamelyn?"

She nods. "They thought it was a combination of 'Tam' and 'Evelyn'."

"So why did she want to name you after this 'Tam Lin' character?"

Tam sighs. "It was the only book to be found in the hovel her family called a home. Frankly, I'm not even sure she was literate enough to read it, but I'm sure she found some comfort in it among the atrocities of her home."

"It was really that bad?"

"Yeah, it was…" She pauses.

I glance at her to see her brow furrowed in confusion.

"I… I don't remember. I know that I went to the house where she grew up, but I can't remember when I did it or where it was. I have only vague details about the place. Why can't I remember?"

"Core you removed several memories from the diary, right? Maybe that's one of them?"

"Yes, but why…?" She trails off.

We're both silent for a while.

"Regardless, my mother wasn't a good person." Tam says. "Nor was she someone I can be proud of, but she was dealt a bad hand."

"I should probably go back downstairs." I say after another bout of silence. "Who knows what conclusions Katie will jump to otherwise."

"Yeah, we don't want your salacious teammate's imagination running wild. I need some time to think, anyways, so expect some silence on my end."

I open my eyes, the curtains around my bed still closed. Well, time to face the world once more.

"About time!" Katie says as I step into the common room. "That must have been one hell of a-"

"I was meditating!" I cut her off.

Katie groans. "Aw, you just have to ruin my fun, don't you? What the hell were you meditating for, anyways?"

"Occlumency reinforcement." I reply tersely.

"Occlu- You're an occlumens!?" She asks, surprised. "How the hell did you become an occlumens at the age of thirteen!?"

"Practice." And a hell of a lot of irreplicable coincidences.

Katie jumps in front of me and grabs my shoulders. "Teach me your secrets!"

"I… really don't know how to explain what I did. Besides, I'm not sure my legilimency is good enough for testing any barriers you try to create."

"You're a legilimens too! No way! Prove it! What number am I thinking of right now!?"

I internally sigh and send out a probe to her mind. It doesn't take long for me to see too much.

"You're thinking of the number sixty nine." I say as I rest my forehead in my hand. "As well as some very graphic depictions of what that implies."

"You are a legilimens!" She exclaims. "How the hell did you have the time to learn two different forms of the Mind Arts by your third year?"

I shrug. "I made time."

Katie whistles. "Well, this explains why Hermione has been complaining about you blowing her off."

"Yeah…" I scratch my head. "I've not been great about… doing social stuff this year. Lots of preoccupations from the Chamber incident last year."

"Well, why don't you go spend some time with her? It'll save the rest of Gryffindor from having to listen to one of her rants about you."

I flinch slightly. "She's been ranting about me, huh?"

"Oh yeah. Not too often, but every once in a while she'll just start going-"

The portrait slams open and Lupin storms in. I can feel the magic radiating off of him like an aura, tinged by the unnatural corruption of his lycanthropy. He immediately casts several charms, including what I can identify as a supersensory charm and an animagus revealing charm.

"-off?" Katie finishes.

"Shush." Lupin commands. His eyes dart to a location on the floor. He tracks… something for a few seconds before groaning. "I'm going to feel this in the morning."

A wave of his wand levitates all of the furniture and rugs in the room. He then presses his wand to the floorboards and uses transfiguration to peel them all back from the beams beneath. I hear a faint skittering noise, and Lupin then lashes out with a wandless Carpe Retractum from his free hand. Whatever he tried to grab clearly got away, as he swears and relinquishes his grip on all of the items in the room before leaving.

"Damn rat." is the last thing we hear before the portrait closes behind him.

"Holy hell." Katie says in awe. "He's been holding back on us in class."

I'm beginning to suspect that we're missing something very big here.

'I'm inclined to agree.'

"Okay, what are we missing?" Tam says as she paces around my mind. "Lupin is clearly chasing after this rat with a passion that defies reason. Why?"

I think back to the first time it happened. It was several weeks ago, but… "Wasn't it several hours after he caught us sneaking out?"

"Right." She nods. "And we didn't hit him with an obliviate that time, so that can't be blamed."

I rack my mind trying to recall the details from that conversation. My experience with occlumency has improved my recall, but I really didn't think all of the details of that conversation were worth committing to memory. I try to think about what we saw him do today. He cast several spells including… "An animagus revealing charm. Could the rat be an animagus?"

"And Peter Pettigrew is a rat animagus. That's what Lupin said to us right before running off. …But no, that doesn't make sense. Peter Pettigrew is dead."

"What if he wasn't dead?" I propose. "He could have faked his death, couldn't he?"

"Yes, but then why would he still be hiding as a rat?" Tam counters. "It's not like he would have had any reason to continue hiding as a rat after Sirius was sentenced. Besides, if Pettigrew was alive, then Lupin wouldn't have been able to tell us about him being a rat animagus at all. Remember how they made an unbreakable vow? The only way he could have told us about Pettigrew was if he had betrayed the others, or was dead."

"That… sounds vaguely familiar." I reply.

"I believe you were in the middle of panicking about Lupin being a werewolf when he mentioned it."

"Yeah, that would be why. So, what if Peter had betrayed the others? That would explain why Lupin could tell us the secret and it would explain why he's been in hiding."

"That…" She pauses to process what I just said. "That actually makes a surprising amount of sense. Okay, we know Sirius is guilty. He was sentenced to life in Azkaban and all that entails, but what if he had an accomplice? Sirius's cover is blown since he was known to be the secret keeper, so he helps Peter fake his death. Sirius gets arrested for it, since he was going to anyway, and no one looks further into Peter Pettigrew."

"That makes a disturbing amount of sense, actually. And now that Sirius has broken out of prison, the two are trying to rendezvous before searching out Voldemort. …Possibly taking me out in the process."

"Well, this does explain a lot of things, doesn't it?"

"It does. So now what do we do?"

Tam looks pensive for a moment. "Well, it does add an additional complication to my plan. It would be easy for us to best Sirius or Peter in a fair fight, but now we have to worry about watching our back while we talk. Honestly, our best bet might just be to get both of them together just to make sure that the message gets across."

"Great, so now we're not trying to catch one escaped criminal — we're trying to catch two."

Tam rolls her eyes. "I'm aware that it's less than ideal, but now we have an advantage. We know that they're trying to rendezvous, so if we can catch them when they do that, then we'll have them both right where we want them."

"That still leaves us with the problem that we don't know where or when they'll be doing it. Even Lupin and presumably Dumbledore are having trouble tracking down Pettigrew. How are we supposed to get to them first?" I ask.

"Okay, let's think. Where would the two be most likely to meet up? We need a location that they both know, that's not directly under Dumbledore's control. Somewhere nearby, but still isolated."

"So we'd need to look at all of the secret passages. Since we know that Pettigrew has been evading Lupin despite the latter's possession of the map, it would probably be in Hogsmeade. Fred and George said that most of the passages are known to Filch, so they're probably known to Dumbledore, too."

"One of them is caved in. Lupin has undoubtedly been watching the one that goes to Honeydukes since he caught us there, so that leaves…"

"Wherever the one under the Whomping Willow goes." I finish. "Where does it go?"

"I don't know." Tam says. "But I think we know someone who does."

I run into Ron and Hermione in the library. "Have either of you seen Lupin?" I ask.

Ron shakes his head. "Nah, he's been running all over the place lately. He barely seems to be paying attention even in class."

"I'm just glad you showed up at all." Hermione says. "I'm trying to work out our study schedules for finals. Do you think we should spend more time on divination or charms?"

I roll my eyes. "I don't have a term to express how little I care."

"You can't just slack off, Harry!" She chides. "How are you supposed to pass your exams if you don't study."

"I'll make do, Hermione."

"Still, you should study with us. Here, you can take this time table I've-"

"I don't give a shit about your damn study schedule!" I yell, against my better judgement.

Hermione just looks hurt at my outburst. I feel bad, but quash the emotion immediately. I have bigger things to worry about.

"I'll see you two later." I mutter as I walk away.

'…No snarky commentary this time, Tam?'

Like you said, we have bigger things to worry about. Let's just find Lupin and get the information we need.

Finding Lupin proves much harder than one would expect over the following week, let alone finding him in a place with no witnesses. He always runs off the moment class is over, and he's rarely standing still. I'd expect it to wear him down given enough time, but if anything, he seems more frantic the longer this search goes on.

I'd wager it's a side effect of his lycanthropy. It's probably activating some latent hunting instincts he tries to keep suppressed.

As Lupin runs out of the classroom while dismissing us yet again, I tag him with a silent tracking charm.

'Hopefully that will do it.'

Less than five minutes later, I feel the charm be dispelled.

'Dammit! How is he this good!?'

I don't know, but it's turning out to be a huge pain in the ass.

'I don't suppose you have any more brilliant ideas for tracking him down?'

Um… maybe? We could try wardjacking, but that's insanely hard to do. It would be extremely obvious, though. Dumbledore would instantly know what we were doing and where we were doing it. The risk of getting caught is too high.

'So that's a no. What if we did it in the Chamber?'

The Chamber uses a separate ward scheme. We would need to be inside the bounds of Hogwarts. Maybe we could use the Room of Requirement to hide. I don't think Dumbledore knows how to get there…

'Couldn't we just have the room take us to where he is?'

…Maybe? I've never actually thought to use it to spy on people. I know that you can't use it to steal from people, but you can use it to take items that are "lost" or "abandoned". There seems to be a bizarre set of restrictions on some of its behaviours.

'Perhaps we should test it first?'

It wouldn't hurt. I never thought to use the Room to track people… Maybe we should see if it can do surveillance, too.

'Now that would be useful. Let's see what we can do.'

Slipping away from everyone ends up being harder than I expected. Hermione's been especially clingy after I blew up at her. She keeps insisting that I need to take time to unwind.

I stand in front of the Room of Requirement and begin pacing.

'I need to find Remus Lupin.'

When I open the door, the Room is in a configuration I've never seen before. Five mirrors sit on the opposite wall, and one sits on each of the walls to the side. The six mirrors on the side are opaque with surfaces that resemble slowly rippling quicksilver, but the one in the centre is displaying an image of Professor Lupin. He's currently running down a hallway while checking the Marauders Map.

I have to admit, I'm a little jealous of his stamina. He's been running for hours every day trying to track down that rat for, what, three weeks?

'Thereabouts, yes. He's just gotten increasingly frantic as this chase has gone on, too.'

That would be the lycanthropy. They hate letting prey get away, and the longer something evades them, the more frantic they get.

It's wholly unnerving to remember that Lupin isn't entirely human — that he's got baser instincts constantly influencing him.

Now, let's actually test our earlier theory.

Tam takes control of my body and speaks to the room. "Show me Peter Pettigrew."

The mirror to the right of the one showing Lupin begins displaying an image. Well, sort of. The mirror is mostly dark, with occasional flashes illuminating indistinct parts of the scenery.

What exactly are we looking at…?

The image of Lupin abruptly stops running and uses a spell to tear out a wall. The image in the second mirror is now brightly illuminated, showing a rat lying among the rubble. It quickly skitters away, dodging spellfire from Lupin, before ducking into a gap under a suit of armour and slipping away again.

'Well, I guess that confirms the theory.'

Yeah, I guess we were right after all. Now, much as I'd love to get the information we need right away, let's see what else we can do with the room like this.

"Show me Sirius Black."

The mirror to the left of the one showing Lupin pulses black for a moment before going back to its passive state.

'So… I guess that didn't work?'

Yeah. The colour probably meant something, but I have no idea what. Let me try a few other things.

"Show me Albus Dumbledore."

The mirror ripples again, this time fading into an image of Dumbledore sitting at his desk.

So it can show us Dumbledore's office. I wonder if it can show rooms?

"Show me the Great Hall."

The mirror to the right of Pettigrew's ripples to show an overhead image of the great hall. A few students are milling about, but no meals are being served at the time.

"Show me the Chamber of Secrets."

The mirror to the left of Dumbledore's pulses black.

The Chamber is outside the Hogwarts wards, so I guess that the black means that it's out of bounds? I wonder if it would block anything inside the ward scheme at all.

'You said the Room doesn't allow stealing, right? Maybe it works off of a morality system? What's something immoral you could do with spying?'

Good question. Um…

"Show me the Prefect's Bathroom."

The mirror pulses red.

Right, that's got to be the sign of it not allowing surveillance of certain areas for "moral reasons". I wonder if the same is true of people.

"Show me Katherine Bell."

The mirror shows an image of Katie sitting in a bed in what I can only assume is the fifth year girls dormitory. A magazine is propped up on her legs.

Well, what do you know, she's behaving herself.

I opt not to point out the nature of the magazine in question.

I have two more things I want to check before we can move on.

"Show me Myrtle Warren."

The mirror on the right hand wall shows a scene of the second floor girls bathroom. Myrtle is floating morosely through the stall doors.

She always was melodramatic. Well, now we know it works on ghosts… Okay, last one.

"Show me Tamelyn Riddle."

The mirror on the left hand wall starts showing… something. Most of the image is flickering black. Sometimes it looks like it's showing a pile of junk. The rest of the time, it's showing me, standing in the room of requirement.

Well, that settles it. We absolutely cannot let anyone else find out about this.

'Agreed.'

I take back control of my body and glance back to the mirror showing Lupin. He's currently taking a breather in an abandoned classroom while eating a granola bar of some kind.

'Perfect.'

Indeed. Are you sure you've got this?

'As sure as I can be. Let's go.'

Alright. I'll take over if it looks like things are about to go wrong. We absolutely cannot afford any mistakes here.

'I know. I've got this.'

You'd better, for both our sakes.

I stand in front of the mirror and speak to the room. "Take me to Remus Lupin."

A seam appears down the mirror's centre, and it opens inward to a dark passage.

I will never understand why a castle has developed such a sense of melodrama.

'Magic, probably. Now let me focus. I really don't want to mess this up.'

Lupin jumps and whirls around when the passage into the room opens, but he lowers his wand when he sees it's me. "What are you doing here, Harry? That passage isn't on the-"

I point my wand at him. Lupin reflexively raises a shield, for all the good it'll do him. "Imperio."

Lupin's shock at seeing me cast an unforgivable makes it all the easier to crush his resistance.

I shudder as I feel the spell take. Tam has cast dark magic in my body, but the euphoria is so much stronger when I cast it myself. It feels so good that I almost lose control of the spell when Lupin begins resisting. I quickly reassert control and begin interrogating him.

"Where does the secret passage under the whomping willow go?"

Lupin's face contorts as he struggles to resist before answering. "It goes to the Shrieking Shack."

Really? Wow, we've just come full circle, haven't we?

"How do I get past the willow?"

"There's a knot on the base of the tree that will paralyse it if pressed. The passage is accessed through the roots of the tree."

"Describe in detail all of the information you know about the enchantments and wards on the tree, the passage, and the shack."

Lupin's face twists again. "The shack was where I spent my full moons transformed as a werewolf. It had a number of protections including containment, anti-apparition, anti-portkey, aversion, and several other wards designed to keep me in and others out. I don't know the specifics, but I know that all of the wards were deactivated shortly after I graduated. The tunnel is meant to be uninteresting. It has several low level aversion charms to make people turn back. It also…"

Lupin starts struggling again. I force the spell on him even harder. "Keep going…"

"Your father… and Black… tampered with the wards somehow. I don't know the details. They became animagi to keep me company, but… there are wards around Hogwarts to… keep unregistered animagi from entering or exiting… unless going in through the front gate… I could never… find anything when I checked. Now that Dumbledore is in on the secret… he checked too. Couldn't find anything wrong… Think it might be time based… Tied to the full moon… Always good at wardcracking…"

Lupin's resisting harder and harder the more I make him talk. I suppose I should end this while I'm ahead. "Obliviate."

I shred the memory of the past few minutes and slip out of the room while Lupin's still dazed.

The next full moon is in six days. Time sensitive wards are extremely tricky, as they're nearly impossible to even detect, let alone dismantle, unless they're active. We're just going to have to hope Lupin's hypothesis is right.

The whomping willow is surprisingly easy to access for something that poses such a risk to life and limb. There are no gates or walls restricting access — the willow is simply perched at the highest point of the cliff overlooking the lake. Then again, that just seems to be Dumbledore's style. He did leave a cerberus in the school with nothing more than a vague warning and an easily unlocked door preventing students from running into it.

Tam takes control and begins casting some diagnostics.

Well, it seems someone has already beat us to it. Looks like there are some recent alert charms tied to specific triggers.

'Lupin?'

Or Dumbledore. Normally, attempting to disarm these trips them, but I did learn a very interesting trick you can do from Salazar's library…

Tam steps away from the willow and moves closer to the outer wall of the great hall. Once there, she casts several charms.

Dumbledore's charms are tied to people pressing the knot on the tree, and people entering the passage in the roots. The charms that I just cast are tied to people pressing this specific brick and walking through the wall, both utterly useless. Now I just have to do a little freeform magic…

Tam starts moving my left hand in slow gestures. I can feel the tingle of shifting magic in the air, and after a few minutes, I feel a sharp snap.

'What just happened?'

I switched the triggers for our alerts. Now, Dumbledore will get an alert if someone presses a random brick or walks through a wall, and I will get an alert if anyone disarms the tree or enters the passage. Because Dumbledore's alerts weren't deactivated, they weren't tripped. No one should be any wiser.

'Should be…?'

It's Dumbledore. He has a way of interfering in things.

'Tam, we have done many things that are either dubiously legal or outright illegal. I really don't want to get caught.'

I know, I know. Look, if we do get caught, we can escape. I have several safehouses that no one else knows about, not even Voldemort. She wanted contingencies in case she was compromised but I wasn't, so she removed the memories from herself altogether. If things get bad, we can fallback to one of those safehouses and rework our plan from there. It would be bad if that happened, but I'm not rushing into things without a backup plan. Unlike some people.

'It was one time!'

But that one time was a basilisk!

'Look, just… you're sure things will work out?'

Of course. We have all the info we could possibly need. Everything will be fine.

A/N (Tendra): Yay, I finally got another chapter for this done! I've been wanting to work on this for a while, but it was really hard to get in the right headspace for the past year. Now that Trump is out of office, though, my mental health has been dramatically improving.

I was also super pleased when I was browsing TV Tropes during the pandemic. Departure from the Diary is listed on nine different trope pages! I love seeing how passionate the fans of this fic are. It warms my heart to know that you're all enjoying my fic this much. I can't wait until DftD earns a page of its own.

So, I was sort of horny when I wrote the first scene. Yes, it really does show. I'm sorry (not really). Every time I try to write Katie, it just becomes… like that.

Many of you were frustrated by the fact that Harry and Tam completely failed to put the pieces of the Pettigrew puzzle together. To be fair, they are very much off in their own world 90% of the time. I'm sure you will all be very pleased to see them finally put their heads together only to arrive at the wrong conclusion. You're welcome.

Honestly, though, the number of fics I've read where Harry and co are able to deduce Sirius's innocence from scattered fragments of information is frustrating, especially given the number of leaps of logic that often occur in said scenes. It's even more frustrating because any reader familiar with canon already knows the "twist". I am a firm believer in defying expectations.

Also, can we just take a moment to feel bad for Pettigrew? Lupin has been chasing the guy near nonstop for weeks, and Lupin keeps pulling out the stops the longer Peter evades capture. Believe me, at the end of this, he'll be glad to just be away from Lupin.

The time-based ward bypass arose organically as I was thinking this chapter over. If Peter has been chased for this long, why hasn't he escaped? For that matter, why did Dumbledore not detect any problems with the wards blocking entrance to the grounds from the secret passages after Sirius first broke in? Dumbledore may be negligent, but he's not an idiot. Dumbledore simply never checked the wards at a time when the bypass was active, and Peter hasn't escaped because there hasn't been a full moon since Lupin started chasing him. He was there when James and Sirius, prodigies that they are, created the bypass, so he knows more about it than Lupin does. It's not a perfect solution, but really, trying to make anything logically coherent out of canon tends to be.

Join my discord at 6YwQewK for early access to fics, previews of unfinished chapters, and miscellaneous ramblings from yours truly.

Next chapter will wrap up year 3!

E/N (Xgenje): I am so angr-e about the Tam+Lin=Tamelyn thing. I am at least a 6 on the spicy mayo scale. Also they raised so many plot flagz through this chapter. Katie is so Horni~ it's kinda cute.

E/N (Foadar): Hmm. Or perhaps Sirius really is guilty?