Alchemy is, at its core, the field of potential. To utilise alchemy is to look at what is and to see what could be. While many branches of magic use the term, Alchemy is perhaps the only one to truly be an "art". None of that actually explains what alchemy is, though.

Much like its sister discipline of Transfiguration, alchemy is concerned about altering the fundamental nature of something. In some ways, Transfiguration is superior, able to turn any substance into any other substance, and in its sub-branch of Conjuration, create raw material from nothing. In many other ways, however, alchemy is a superior art. After all, while alchemy always requires a starting substance, any changes induced by Alchemy are permanent. While basic alchemy only allows for the reshaping of material into a new form, more advanced forms are able to create more of a substance from a small starting sample, or even change a material into a new form by utilising shared properties to enforce relationships between substances.

The highest form of alchemy is that of blood alchemy. After all, what is more artful than using magic to manipulate the essence of life itself?

Contrary to what the name might imply, blood alchemy does not always use blood as a starting substrate. Indeed, any form of organic matter, be it muscle, organ, or even bone, can be used as a substrate. Blood is, of course, the preferred material, as samples can be obtained with far greater ease and kept stable for much longer periods of time.

The core downside to alchemy in all of its forms is that it does not mix well with other forms of magic. Blood alchemy can be used to heal mundane injuries (though it is usually very inefficient to do so), but any sort of magical injury must have the lingering traces of magic scoured before it can be alchemically healed. In the case of curse wounds, whose magic is nearly impossible to eradicate, alchemical healing is effectively useless.

Despite the comparatively limited scope of blood alchemy as a healing mechanism, it does have its uses. For example-

'Tam, this book is the most boring thing I have ever read.'

At least let me get through the introduction before you refuse to read it. Now then…

"For example, a limb that was amputated through non-magical means is most easily grown back through blood alchemy. The standard healing practices for regrowing both bone and flesh interfere with each other, which can result in mangled limbs and faulty regrowth. Blood alchemy cannot interfere with itself, making the process much smoother.

Blood alchemy can also be used to induce permanent changes in a mage's body. For example, some mages will find themselves uncomfortable in the body they were born in, and can undergo a blood alchemy treatment to change their body to a more comfortable form. This is normally used to turn a male body into a female one and vice versa, but eccentric folk throughout the ages have occasionally requested more exotic changes, such as the tale of a man in-"

'No, Tam, I can't do this. I just can't do this.'

Do what? Read?

'No, I mean I can't just do nonstop theory studies the way you can, let alone study a text as dry as this one. I need to actually do something once in a while. We haven't done any extracurricular spellwork in two weeks — just nonstop theory.'

Harry, I understand your desire to get out and do things. Unfortunately, for the time being, the best course of action for us to take is to work on getting me a body. The sooner I am able to operate independently of you, the better. My ability to gather information is limited when I am borrowing the body of a student who spends most of their time in school.

'Well… if it's that much of an issue, couldn't we head into London and do some information gathering there?'

I'd say that your legilimency practise has already gotten us most of the information we need from the muggle world. Although…

'Yes?'

We need more information about the state of the magical world. How would you feel about another excursion with an impromptu lesson?

'Yes, please.'

Good. We'll need your invisibility cloak for this one. We can't just go around surreptitiously casting on people in Knockturn Alley like we can in Muggle London, so we'll need a way to stay unseen.

'This won't be… dangerous, will it?'

As if you have any right to ask me about doing something dangerous, what with your deadly broom stunts and willingness to run headfirst into danger. But no, it won't be dangerous. While there are some truly dangerous people who frequent Knockturn Alley, a majority of its occupants are drunks and outcasts. We won't be picking any fights and we won't be dealing with anyone dangerous.

'Will drunks and outcasts really be able to give you better information than you can get in Hogwarts?'

The Hogwarts Library is one of the greatest repositories of knowledge in the world, but… History is written by the victors. Many of the history tomes there, especially the modern ones, don't paint a wholly accurate picture because they don't show the losing side of the story. I need a more nuanced take to really start understanding what happened during the past fifty years…

'Alright… So what will I be learning from this little excursion?'

Only the most overpowered mind art in existence — Obliviation.

I take a backseat as Tam walks my body to the passage and outside the boundaries of the anti-apparition wards. While I will never admit it to her, it's nice to be able to take a backseat to my own life once in a while. Letting someone else do things for a change has been an amazing stress reliever, not to mention that it gives me much needed time to think.

…I feel no guilt at making that admission, if only to myself. I like Tam, dammit.

I really wish I had an invisibility cloak like this when I was in school. It would have made sneaking around much easier.

'Oh, yeah, it's been amazing.'

I had to wait until I learned the disillusionment charm, and even that's just highly effective camouflage, not actual invisibility. An invisibility cloak can fool anything short of a wardline or a revealing charm.

'…I'm realising that I don't know as much about invisibility cloaks as I probably should. I just sort of settled at "they make you invisible" and didn't really think to look further into them than that.'

Eh, even I don't know much more about them than that. I only know that much because of my studies of wards.

'Oh, so you're not going to give me crap about not learning as much as I can?'

I feel Tam bristle at my teasing tone.

You're working to fix the situation, which is more than most people would do.

'Why, did the great Tamelyn Riddle just say that I'm improving? Possibly even meeting her standards? Clearly this is the greatest compliment that has ever been bestowed upon me.'

Harry?

'Yes?'

Shut up.

If I was in control of my body, I would be giggling like a loon right now. As it is, not even the uncomfortable sensation of apparition kills my glee.

'So, what's the plan?'

I'm going to find someone who looks like they couldn't resist a good confundus charm, first of all. I'll discreetly confund them to go into one of the smaller side alleys and rip through their minds with legilimency until I have the information I need. Then comes your part of the lesson.

'Where I wipe the memory of the experience from their heads?'

Exactly. Now then, just give me a moment to find an acceptable target.

Feeling Tam do deep scan legilimency while in control of my body is always a surreal experience. Performing legilimency tends to reduce one's awareness of the physical world, with greater effects for more involved legilimency probes. Coupled with the fact that my awareness of physical sensations is numbed when I'm not in control of my body, and the two stack in such a way that makes it easy to forget that I have a body at all.

I feel the vestiges of the physical world return to my awareness as Tam withdraws from the junkie's mind.

All right, ready for your part?

'I suppose. How do I go about doing this?'

The wand movement is a right-sided clockwise semicircle swish, followed by an upwards flick. You already know the incantation. Once you've cast the spell, you'll instantly connect with the target's mind, like a direct legilimency probe. From there, you can use your knowledge of legilimency to navigate through the stream of memories until you find the one you're looking for. You won't be able to get a lot of details from memories while accessing them like this, but that's not important.

'So, what do I do when I find the right memory?'

Well, there are two ways to erase a memory. One of them involves severing the connections between that memory and others before pushing it down into the depths of the subconscious. Unfortunately, this method can be undone by either studying occlumency or by having someone who experienced the erased memory restore it. I have no interest in reversible memory charms, so we'll be doing an alternate method that I discovered by myself.

'Which is?'

Grab the memory by the seams and tear it to shreds. Rip the very fabric of the memory into so many pieces that it can never be reconstituted before letting the fragments dissipate into the mind.

'Um… wow.'

This method has its own downsides, but the irreversibility far outweighs them. So long as the target doesn't have intact occlumency defences, you can permanently scour any memory from their mind. Now, give it a shot.

Right. I take a deep breath and focus on the task at hand. Right half swish, upward flick, and…

"Obliviate!"

The spell bolt is large and impossibly white, but doesn't give off any light in spite of that. I don't have much time to ponder that oddity before the spell connects and I find myself thrust into his mind.

The memory I find myself in is not Tam's legilimency interrogation, but some much older memory. He's dressed in some sort of soldier's uniform while fighting on a battlefield. He's immobilised and watches as someone else on his side takes a bright white spell that was meant for him. I'm not able to get any further details from the memory, but I am able to put together that seeing me fire a white spell at him made him recall this event. I feel a brief pang of sympathy but immediately quash it — this isn't the time for such emotions. I feel out for the memory's threads and find the right one to trace back to the memory of Tam using legilimency on him. I check to make sure that it's the correct memory — I wouldn't want to accidentally erase the wrong one — before I reach out with my magic and slowly rip the memory to pieces. The fragments of torn memory dissolve into nothingness as I slowly shred my way through. When the last of the fragments have dissolved, I withdraw from his mind.

That took longer than I thought. You're usually much faster these days.

'I had to deal with some unwanted emotions.'

Oh, yeah. Those get easier to suppress with time. It took me a while before it was this easy.

'Hmmm…'

So, are you ready for more?

'Yeah… lead the way.'

Tam shifts into control of my body and stalks down the alley in search of her next target.

'I'm really wishing I could get more details from some of these memories.'

That's reasonable. I imagine the lack of clarity is part of the tradeoff, since normal legilimency is only good for viewing memories, not editing them.

'It's possible to create fake memories, right? Or just edit out parts of a memory?'

Tam confunds the next target before replying.

Technically, yes, but it's extremely hard to do well. You would have to accurately map all of the sensations from the memory and make sure the resulting threads are connected properly. I mean, you'd need to think about all the sensations that are part of the memory, and then you'd need to make sure that they're balanced according to that person's natural sensory priorities, and so on… Not to mention that olfactory memories — memories of smells — are incredibly hard to fake, as the mind processes them differently than other sensations.

'So, it's possible, but impractical?'

Basically. Hold on, I need to get to work.

Tam dives into the muggle's mind, leaving me alone in my body. I try retreating to my mindspace, but find it incredibly easy to get bored there without company. After faffing about for another few minutes, I start reinforcing my occlumency barriers. They've been steadily improving with time, but manually reinforcing them periodically helps them stay strong.

Alright, done.

'Awesome. So, what were you saying about faking memories before?'

Oh, that. Well, it's possible, but it would require an extremely intimate knowledge of a person's mental structure to create a false memory that they wouldn't immediately identify as such. Besides, in the time it would take to create one would be prohibitive in most timeframes. It's not like one often has hours to spare to perform an obliviation. No, it's generally easier to tear a memory to shreds and let the mind fill in the gaps. Speaking of which?

'Right.'

I take control of my body and level my wand at the woman. She's dressed in rags and shaking in fear, but I quash the feeling of sympathy with far greater efficiency than last time. Besides, it's not like this will hurt her.

"Obliviate."

I take back control of my body once Tam apparates us back to the passage. Obliviation is… surprisingly easy to do. I mean, I know Tam says that I'm skilled in the mind arts, but it feels like erasing memories should be harder than viewing them. Some part of me still feels uneasy about performing obliviation at all, but Tam's right — it's an incredibly useful skill to have, and I'd be remiss not to study it. Even if it wasn't a necessary skill for maintaining the Statute of Secrecy, it's a must-have for anyone prone to sneaking around. Anything that helps me reach Tam's level can only be a good thing — I can't always rely on her to be able to fix my mistakes.

As we near the entrance to the castle, I realise that Tam's been unusually quiet, which usually means she's contemplating something.

'What's on your mind, Tam?'

Hm? Oh, I don't know, I just… I'm trying to make sense of what I learned.

'What, did you learn anything unexpected?'

Well, not exactly… I'm just feeling like I'm missing some key factors about what went on in the war.

I don the invisibility cloak before hauling myself out of the back of the statue and jumping down to the ground.

I mean, even if my core self was playing some grander game, there are so many things that don't make-

Tam's thought is cut off as the invisibility cloak is lifted off of me.

I turn around to see an invisible figure fade into existence, cloak in hand.

"Sneaking out, are we, Harry?" Professor Lupin asks.

'Shit.'

Shit.

"I wasn't sneaking out, Professor." I say, trying to play the innocence card. "I was just trying to get around the castle without being seen. Are you saying there's a way out of the castle around here?"

Lupin just laughs. "Oh, that really takes me back. Your father also loved to play innocent when he got caught. Unfortunately for you, I can confirm that you were definitely in this passage mere moments ago, and I suspect this wasn't the first time. Am I right?"

I don't say anything, which is all the answer he needs.

His humour dries up and is replaced with resignation. "Harry, I understand the appeal of breaking the rules better than anyone. In fact, I'd even be willing to overlook you sneaking out if you did so on a weekend and if there wasn't a convicted felon out for your blood. As it happens, though, neither of those are true. I'm afraid that I can't overlook this. As such, I'll be having Albus restrict access to the emergency exits until Sirius Black is either caught or killed. I'd normally be confiscating the cloak, too, but I wouldn't want to take such a valuable defence from you. See that you don't abuse it so heavily in the future."

I clench my fists in frustration as I try to keep the rage from showing on my face. "I understand, Professor." I say, doing everything to keep my voice cool. "If you don't mind my asking, what made you think I was in the passage?"

"Well, the reason why is… I'm not actually sure. I had a strange hunch that you had been sneaking out and decided to follow through on it, just to be sure. I didn't want to believe you would be so reckless, but…"

Crap. I should have seen this coming.

'What?'

I'll explain once we're out of his hair.

"As for the how, well… I suppose I may as well tell you. You… do have a right to know, to some extent. Besides, it's not like knowing how I track you will let you get around it." He pulls out a piece of parchment, presses his wand to it, and says "I solemnly swear that I am up to no good".

Ink flows across the parchment, scribbling out a message identifying itself as the product of "Moony, Wormtail, Padfoot, and Prongs" before using some rather fancy calligraphy to label itself as…

"The Marauder's Map". Lupin says wistfully. "It was the result of years of work between me and my friends back in our schooldays — your father, Peter, myself, and… Black. We lost it before we graduated, but I was able to track it down shortly after the school year started. I've been using it to keep an eye out for Black, but I was… recovering from illness when he snuck in on Halloween. He has an… advantage that makes it hard for people to recognise him."

I wonder why Lupin's being so cagey about stuff that I already know, like his lycanthropy and Black's animagus form, before remembering that Tam obliviated that conversation from his mind.

I should feel bad for him, but it was a natural course of action for Tam to take, especially after I lost my cool due to coming in direct mental contact with a werewolf.

"This map shows everyone and everything happening in Hogwarts at this time. You can see all of the various secret passages throughout the castle, and the map even tells you how to get inside of them when it's used outside of one."

It's mind-bending to look at the maps' portrayal of Hogwarts's alien geometries in a two-dimensional Euclidean space. It's like staring at an Escher drawing that someone converted into a map. I close my eyes and start rubbing my temples after my fifth attempt to understand how some of the space-bending passages are accurately mapped on the parchment.

"Ah, yes, it's best not to stare too closely at some of the areas — rather headache inducing, as I've learned from experience. While that's definitely the map's most interesting feature from an academic standpoint, the feature we made the most use of was the ability to track people. We used this thing to avoid Filch so many times."

I perk up at that description. It can track people?

Harry?

'Yes?'

We need that map.

'I know. That'll take a lot more obliviation than I'm comfortable with doing at my level of experience, so I'll let you do the honours.'

Got it. I'm taking over now.

"So, it shows where everyone is?" Tam asks as she moves beside Lupin to get a better look at the map. "Even in common rooms or offices?"

Tam discreetly pulls out my wand as Lupin smiles. "Of course. If you look here, you can see Dumbledore making a floo call, and if you look over here, you can see your friends Ron and Hermione in the Gryffindor common room, along with-"

Lupin freezes and his eyes go wide as he stares at the map. I feel Tam tense my arm as she stops her attempts to cast the spell.

"No… no, it can't be. If he's… then that means… But the vow… but if we thought he was…"

Tam tries to sneak behind Lupin so she can catch him by surprise.

'You could just obliviate him to the face, like you did last time.'

I had the element of surprise that time. I don't, this time. He's obviously on alert, and I believe that some part of his mind may be prepared for this.

'How could he be…?'

Later.

Unfortunately, Lupin whirls around to face us before Tam gets to a good angle. I feel her freeze as he stares at us.

"Harry…" Lupin says slowly. "Peter Pettigrew is a rat animagus."

I can feel Tam almost answer in the affirmative before remembering that we're not supposed to know about that. "Okay…?" She replies hesitantly.

I can see something click in Lupin's brain as she replies. "I'm sorry, I have something very urgent to take care of right now." With that he dashes down the hallway. Tam raises her wand to try and hit him with a memory charm, but he turns the corner before she can get a clear shot.

Godsdammit!

Before we can do anything else, Lupin's wolf patronus appears in front of us and speaks. "I almost forgot to finish dealing with you. You have detention with Filch for a week. I'll be delivering you a note to that effect at dinner, just so you can't pretend that you never got this message."

'Son of a bitch.'

I'm not sure that's technically accurate, since he was infected with Lycanthropy, rather than being born with it.

Tam's joke slightly improves both of our sour moods. After taking a moment to lament this turn of events, I take back control of my body and start walking back to the Gryffindor common room.

'Well, I guess that puts an end to our excursions.'

Yeah. There are still spells I can teach you, but we can't do anymore mind arts without unwitting targets. I'm still just annoyed that I didn't see this coming.

'How could you have seen it coming? I mean, it's not like you could have stopped him from having that uncannily accurate hunch.'

Tam sighs.

Harry… That wasn't a "random hunch". You know how I described two methods of obliviation to you?

'Yeah?'

Well, the method I taught you is irreversible, but, the memories don't entirely go away, either. When you shred a memory, it fades into the mind, but because it's not suppressed first, the ideas of the memory still linger, manifesting as hunches and impulses.

'So you're saying that even though you obliviated Lupin, he still had some vague, subconscious idea of what happened?'

Essentially. It's why I kept trying to sneak behind him before obliviating him, as he might have been prepared for a frontal attack. Still, I don't think either of us could have seen the map coming.

'No. I know Fred and George said that they had a map, but I thought they were exaggerating its abilities, not understating them.'

Unfortunately, I think we've lost this round. Lupin noticed something on the map and ran off to tell someone. I don't think it will be long before Dumbledore knows about both the map, and our sneaking out, and we don't know who else they'll tell, too. Our window of obliviation was lost.

As I turn up the next flight of stairs, I do my best to remember everyone else Tam has obliviated, trying to determine if any other obliviation she's performed is likely to bite us in the arse. She obliviated Vernon a few times, but I couldn't care less about him, and he lacks any real power over me now that I'm not bound by the Trace. I'm pretty sure that everyone else she's done it to isn't someone we're likely to encounter again — everyone except…

'Hey, Tam?'

Yes?

'How likely is it that Ginny will remember what happened with the diary and the Chamber?'

I feel her thinking it over for a moment.

There are enough factors in play that I can't say with any degree of certainty. If I were to guess, however, I'd say that she probably wouldn't. The soul damage should probably interfere with her subconscious enough that it won't be an issue. I'm… not actually sure what the aftereffects of someone being obliviated of a possession attempt are, though, and I'm not in any rush to find out. While I don't think she'd discover me if I start poking around her mind, the risk is far too extreme for me to consider it.

I enter the Gryffindor common room and slump down into a chair near Ron and Hermione, ignoring the greetings they say to me.

'What do you think Lupin noticed on the map?'

I haven't the slightest idea. It's probably not something that we need to concern ourselves with, though.

"Knight to D6." Ron says, claiming my bishop that had placed him in check. I really should have seen that one coming, but I often forget to look for knights. My brow furrows as I take in the new state of the board, trying to determine the best move I can make now that I lost what I thought was my one opening…

'You know what, Tam?'

What?

'I don't think I'm very good at chess.'

No, you're not. I'm… not terrible at the game, but I doubt that even I could beat Ron. He is, admittedly, very skilled at this game.

'So… what move would you make in this situation?'

Hmmm. I would move my…

"Rook to C2."

We both pause as we realise that Tam managed to get me to say the words despite not being in control of my body at the time.

'What the fuck?'

What the fuck?

"Checkmate." Ron says as he captures my rook and ends the game.

I put on a show of groaning as Ron smiles smugly, but my focus is elsewhere.

'Tam, how were you able to do that?'

I don't know! I mean, I've been able to induce basic physiological sensations when I'm not in control, but this is different! Controlling vocalisation is hard! I could barely get Ginny to say anything even when I was actively possessing her!

'So what does that mean?'

I don't know!

'How do you not know!? Aren't you supposedly knowledgeable on soul magic!?'

No one these days knows much about soul magic! I know more than most people because I know any at all, but…!

'But what?'

I don't know. Maybe I haven't been managing the personality bleed as well as I thought I was? We may want to take a chance to meditate to make sure things are still in order.

"I'm going to go lie down for a bit." I tell Ron. "I'm not feeling great right now."

He nods understandingly. "Alright, mate. I'll bring you some food if you're still not feeling well when dinner rolls around."

I mutter my thanks as I start to pack my things up. For all his faults, Ron is a good friend. My train of thought is interrupted when Lupin comes into the common room, though.

"Has anyone seen a rat?" He asks us.

Ron and I exchange a glance before shaking our heads. Hermione is too involved in her homework to bother answering.

Lupin sighs. "Well, let me know if you find one, will you? Don't catch it, just let me know if you see it."

"Wonder what that was about." Ron muses as Lupin leaves the room. "Do you reckon a creature from one of his lessons escaped?"

I shrug. "Maybe. I mean, it's not like we see rats around the castle much, Scabbers excluded."

He laughs. "Yeah, but why would they be after Scabbers? He's just a lazy old lump!"

I shrug again and shoulder my bookbag. "Yeah, it doesn't make much sense, does it? Well, I guess we'll keep an eye out for him. See you guys later."

Ron nods and sets up another game of chess while Hermione just makes a slight grunt as she turns the page in her book.

Once I'm certain that my bed curtains are sealed and silenced, I sit in the middle of the mattress and close my eyes.

'So, what exactly are we doing?'

I'm going to close myself off from you to prevent any further issues from potentially cropping up. Once separated, we are each going to do a deep scan of our own minds, looking for anything odd or out of place. When you find something, because I have no doubt that we will, isolate the oddity from the majority of your consciousness. Tap on the barrier when you're done and we can sort through them.

I can tell just by listening to her that Tam already has a good idea of what's going on, but doesn't want to bias me until she knows for sure. I push that thought to the side — somewhat literally, now that I'm in my mindspace — and set to work.

This is not going to be fun.

Deep scans of the mind, in both occlumency and legilimency, are humongous pains in the arse. It involves parsing through literally every single memory, thought, and thread, checking for coherence, signs of tampering, and origin of the thought. To say that it is a time consuming process is an understatement. It is a time devouring process. I've performed deep scan legilimency twice during my various lessons, and each attempt took the entire duration of the lesson. And that was just on muggles with no mental magic to speak of!

I'm definitely going to be missing dinner. If I'm lucky, I won't miss breakfast tomorrow morning, too.

I decide to start at my earliest memories and thoughts, rather than the most recent ones — better to get all the nastiness at the Dursleys out of the way.

There are several experiences that predate the night when Voldemort killed my parents. It would be an exaggeration to call them memories, as they're more vague sensory experiences with no real context. I look them all over, giving only the vaguest of glances at the scents, remembering what Tam said about olfactory memories being extremely hard to fake. As it happens, that apparently makes a lack of smells one of the biggest indicators of a falsified memory. Everything there checks out, so I move on to the less comfortable later years.

I do my best to analyse every memory as thoroughly as I can while minimizing the amount of time I'm exposed to its contents. Once I start finding some repressed memories, though, I realise that this will be more work than I had hoped. Luckily, I already know what to do. Repressed memories are a common enough occurrence that both of my previous targets for deep scans had them, which Tam then had me unravel.

While memories are what makes up most of the substance of a mind, threads are what keeps everything together. Threads connect stimuli to memories and memories to other memories. A repressed memory is a memory in which the threads have all curled around the memory, preventing it from connecting to anything and keeping it out of conventional recall. To undo the repression, all of the threads have to be uncurled and allowed to restore their connection with the rest of the mind.

It's an involved, but not difficult, process. Once I've peeled back enough threads, the remainder unfurl and begin restoring their connections. With that out of the way, I look at the contents of the memory.

It's a memory of accidental magic. Of course it is. Such memories were safer to block out than believe in, lest I attract further ire from the Dursleys for talk of "magic". The magic itself was simple — a glowing ball of light conjured during one of the earliest times I was locked in the cupboard, back before I'd gotten over my fear of the dark through sheer necessity.

As I continue to work my way through the memories, I find more repressed memories that I gradually unravel. A time that I blew up a lightbulb because Vernon yelled at me, only for him to yell louder. Making a toy float over to me after Dudley tried to take it only for Petunia to shriek at me for using my unnatural powers to steal from him.

There are only a handful of memories along those lines, but they all have the same theme of me being horribly punished and often terrified for doing something innocuous with magic.

I really should kill the Dursleys. I'd be doing humanity a service.

I don't notice anything else odd about my memories as I continue to work my way through them. It's not until I'm almost done that something finally catches my attention.

When Lupin showed me the Marauder's Map, I mentally compared it to an Escher Drawing. I know what an Escher drawing is and can think of several examples.

I can do all of that despite never learning about them.

I carefully separate that knowledge from the memory. I almost missed it completely. If I almost missed that, could I have missed anything else?

I search back through recent memories for anything else like that. I keep finding out-of-place knowledge of classic literature, as well as a few instances of mathematical theory. I group them all against the barrier. Once I think I've gotten it all, I tap on the barrier. Tam opens a gap and immediately shoves a bunch of knowledge at me.

I believe this is yours.

The information easily slips into my mind. Despite the quantity being large, I don't feel overwhelmed. It's almost like none of the knowledge is new to me.

So, what did you find?

'Mostly stuff about literature and math that I can't recall learning.'

Tam pulls the knowledge into her own mindspace.

Yeah, as I thought. This is all mine.

'How did it get into my mind, then?'

You know how I talked about personality bleed? This is a subtler form of that. I've been trying to undo the bleed as it happens, but I was too focused on dealing with the big things. Little bits like this have been slipping under my radar. As a result, we had been slowly bleeding together enough that I was able to make your body do something despite not being the one in control.

'So… how do we fix it?'

There are three ways I can think of. The first is that we get me a body. That would fix the issue permanently, but we are still nowhere near ready, and I don't want to waste samples of my blood trying until I'm more sure of my abilities.

The second is that I keep my barriers up on a near constant basis. That will prevent anything from leaking, but it will also prevent us from communicating and prevent me from having much sensory awareness of your body. I consider this the least ideal course of action, for multiple reasons.

Well, we're in agreement on that one.

The third choice is probably our best one. We perform deep scans like this one on a weekly basis to fix any minor bleed.

'That sounds like an utter pain in the arse, but given the lack of other options…'

I know. It's not ideal, but we need to make sure that we keep this under control. While I've come to terms with our situation, I really don't want to lose my sense of self, not after I've had to work so hard for it.

'I don't suppose there's an easy way we can keep track of this?'

Well, we can't monitor the bleed directly, but continued personality bleed might lead to some other odd effects that we can track… Head to your water closet. I'll need a mirror for this.

I open my eyes. A wave of my wand parts the curtains, revealing a room cast in shadow. I can hear the various snores of my roommates as they sleep. I also feel very hungry from having to skip dinner. I notice that Ron kept his word and left a sandwich and some pumpkin juice on my nightstand. I devour the sandwich and make my way to the water closet.

Once the door is shut behind me, I turn on the light, nearly blinding myself in the process. I hastily wave my wand, casting a weak darkness spell to dim the lights. When the spots have finally cleared from my vision, I stand in front of the mirror.

'So, what do we need to do?'

I'm going to cast a diagnostic charm on us, and we'll need to be looking in a mirror to see the results.

Seems odd, but okay. I pass Tam control of my body and she points my wand directly at my chest.

"Anima Chromatis."

The centre of my torso lights up with colour. Most of the colour is a vibrant green, but a mass of red, maybe around half the size of the green, is attached to it. The two colours blur together where they meet.

'What am I looking at?'

Chromatic manifestation. Every person's soul has a "colour" that it shows when it's either manifested or projected onto the physical plane. That…

She points at the green.

…is your soul. And that bit…

She points at the red.

…is the part of my soul that's attached to yours. You can see that I have less soul than you, due to splitting it.

'And that means that the blurred bit is where our souls are bleeding into each other?'

Precisely. Right now, there is a significant, but not alarming, amount of bleed. Should we keep with the regiment consistently, the bleed should gradually lessen.

'Great. Because we clearly don't have enough to do already.'

Gods, I know. It's just one thing after another with us, isn't it?

'At least we managed to cross learning the Patronus charm off our list before this came up.'

That's true. It's a good thing that you have almost no social life, because we're going to be very busy.

'I… agree with the sentiment, but object to your choice of wording.'

Well bully for you. Come on, Harry, we have things to do.

"That wall had better be spotless!" Filch says from the other side of the hall.

I roll my eyes and discreetly cast scouring charms as I wipe at the wall with the sponge. Filch wants me to do this without magic, but whatever paint Peeves used in his latest act of vandalism was obviously designed to resist non-magical removal. Just because Filch can't use magic doesn't mean he should take out that frustration on other people.

At least cleaning is habitual to me. As I settle into a rhythm, I start moving my body on autopilot and pull most of my awareness into my mindspace. If I don't need to be paying attention to the work I'm doing, then I may as well have my consciousness do something useful. I manifest a form for my consciousness and stare into the black abyss of my mind.

"It's actually eigengrau, not black." Tam says as she manifests behind me. "The human mind finds it to be a more comfortable colour than pure black."

"Whatever." I say with a shrug. I sit down on a nonexistent chair as Tam does likewise.

"You're improving." She notes.

"It's just practice, isn't it? It's not like it's hard to learn — it just requires experience to do so."

"While that's true, I was also referring to the fact that you split your consciousness without me telling you how to do it. That's impressive — even I was never good at doing that."

I fail to hold in my surprise. "Wait, really? It just seemed natural to me."

Tam shrugs. "I imagine some of the differences in our upbringing contributed to it. We are similar, but we're not the same. You were given a lot more menial work to do that didn't require a lot of conscious effort and only had to stay on guard when your uncle or cousin were in bad moods. By contrast, I was constantly on alert against the other orphans and the adults. It wasn't safe for me to let my guard down, so splitting my consciousness and having one part of me lose awareness of my physical body was never something I was comfortable with doing."

I nod understandingly. "It's pretty fucked up, isn't it? Just in general."

She sighs. "Yeah. Yeah, it is. The horcrux creation didn't really help matters, either."

"What…" I pause, before deciding to go ahead and ask the question that's been weighing on me for some time. "What exactly happened with you making horcruxes, anyways?"

"That's… that's a long story."

I gesture to the empty space around us. "There's literally nothing going on in here. I'd say we have lots of time."

Tam lets out a small groan. "Fine, I suppose you have a point, and you need to know this anyways. Before we can get to any of the actual steps that lead to the creation of my first horcrux — me — you'll need context. You already have most of the necessary memories, but there's one more you need to know. This memory shows you how I first came across the existence of horcruxes in the first place."

I didn't expect the path to immortality to be an easy one. After all, if it was easy, then lots of people would have done it.

Okay, that wasn't entirely fair. There were lots of people who were immortal, but none of the common methods were up to my standards, and many of them were mutually exclusive. Vampirism protected one from aging, but it didn't protect one from being killed and introduced a whole slew of new vulnerabilities. No, vampirism was definitely out.

The Philosopher's Stone was a better alternative to vampirism, but it was heavily reliant on the consistent brewing of a potion to stave off aging. It didn't have any downsides like vampirism did, but it still wouldn't protect one from the destruction of their body. I let out an involuntary shudder at the mental image of being blown apart by a bomb. No, that was definitely out.

There were other forms of undead that granted immortality much like vampirism, but the only one that was remotely promising was lichdom, and even that was something that I balked at. Becoming a lich involved completely removing one's soul from their body and storing it in a phylactery. The body would live… in a sense, controlled remotely by the soul. The downside to such a method was that, in removing the soul from the body, the body was no longer able to channel magic. I'd hardly consider a life without magic to be a life worth living.

Alas, even with Slughorn constantly granting me access to the Restricted Section and scouring it for years, I've barely made any further headway. Whatever method of immortality I seek either can't be found in Hogwarts, or does not yet exist.

If it turns out that the method I desire doesn't exist, then I will make it exist. I refuse to bow to such petty concerns as death.

I slump into my seat at the back of the History of Magic classroom. I take out my notes for various other projects. I'm almost done working out the runic matrix that will allow each page to store multiple memories. From there, it will just be a matter of inscribing the runes on every single page, plus some binding and containment runes into the jacket. It will be hard work, but the possibilities opened by this will change the field. The average pensive can store several hours of memories at most, but this… this can store years of memories. I could render the entire pensive industry obsolete once I can figure out how to mass produce diaries like this one.

That thought is interrupted as, for the first time in my Hogwarts experience, Binns catches my attention.

"Excuse me, Professor?" I say as I raise my hand. The student next to me moans in his sleep.

"Yes, Miss Rimple?" Binns says in his usual droning voice.

"You just said that Herpo the Foul was able to survive not only being killed, but the complete destruction of his body. What sort of magic would make such a thing possible? He clearly wasn't a lich, given that he fought his attackers off with magic."

"The exact method Herpo the Foul used to attain his immortality is not something mentioned in any modern texts, likely purged from the records by many publishers and governments. Whatever method Herpo the Foul used may have been unique, as he was known for experimenting with magic, even creating the first basilisk."

My mind flashes to Tessie.

"Alas, any answer is not likely to be found outside of first-hand material on the event." Binns concludes before going back to his usual droning lecture.

I go back to studying my notes, grinning internally. It may have only been through an aberration of chance, but I finally have a lead — Herpo the Foul.

I come back to existence in my mindspace.

"Binns!?" I ask, incredulous. "You learned about horcruxes from Binns!?"

Tam laughs. "Isn't it brilliant!? Who would have thought to ask him! He's so dull and boring that I didn't even have to cover my tracks! Everyone else in the room was asleep and he probably has no memory of the conversation in the first place! I was free to pursue the works of Herpo the Foul and no one was any the wiser until I'd already succeeded!"

"So, that was the last bit of context you needed to show me? Now we can get to the point where you were created?"

"Well, yes, but… We should probably avoid having you view multiple memories without doing deep scans in between. Our presences are never closer than they are when we're viewing each other's memories, so it's not something we should do often. It's really for the best that we've been doing it infrequently up until now."

I groan and flop back onto the ground, vanishing the seat beneath me with an automatic flex of will. "I'm kind of annoyed that I have to be spoon fed these memories."

"You're not alone in that." Tam says with a sigh. "Creating a horcrux was the single most painful thing I've ever done, and… I really hate to admit it, but I fucked it up pretty badly. I don't like dwelling on the details of my mistakes, so I'd really prefer to get this over with as soon as possible."

Oh. Well, that's fair. No one likes to admit that they fucked up, much less relive their fuckups. "I should probably get back to my body."

She nods. "That's not a bad idea. Good luck re-merging your consciousness. I'd offer advice, but I have none to give."

I roll my eyes. "Thanks, Tam."

I open my eyes. The wall in front of me is essentially clean, though I've still been scrubbing at it for some time while operating on autopilot. The re-merging process was so easy that I find myself wondering if I did it wrong.

Nope, you managed it perfectly. I have to say, I'm genuinely impressed — you've managed something on your first try that even I never managed to do.

I feel an initial urge to brush off the complement before deciding to accept it. Just because what I did was instinctual doesn't mean that it wasn't impressive.

'Thanks.'

I rinse and dry the wall with a wave of my wand. "I'm done, Mister Filch."

"What do you mean you're done!?" He snarls. "You can't be done if I'm not done!"

"Well, my wall is clean. Just because yours isn't doesn't mean I haven't satisfied your conditions."

I can see his brow twitching in frustration. "Fancy yourself a cheater, do you? I told you that you were to clean this wall using your own sweat and blood, none of your fancy wand-waving."

I raise an eyebrow. "Just because I'm able to work more efficiently than you doesn't mean I was cheating."

He sneers at me. "Get out of my sight."

Well he doesn't need to ask me twice. I turn to march down the hall, only to come face-to-face with Lupin, Marauder's Map in hand.

"Have either of you seen a rat?" He asks.

I shake my head as Filch grumbles under his breath.

Lupin sighs. "Damn. I mean… Darn. Well, let me know if you see a rat around, would you? It's rather important. Stun it and bring it to me if you think you can do so without scaring it off."

Filch's grumbling grows more demented at the mention of magic.

"Or, well, come fetch me if you see a rat, Argus. Just try and avoid scaring it."

He goes back to his futile scrubbing at the wall as Lupin turns to me. "Do you want me to escort you back to the common room, Harry?"

I shake my head. "I'll be fine, Professor. Good luck on your rat hunt."

Lupin nods solemnly. "Thank you. I have a feeling that I'll need it."

What the hell is so special about this rat that it's gotten Lupin into such a tizzy searching for it?

'The Weasley twins probably put some joke potion on a rat and Lupin's been desperately trying to contain it.'

Ah, yeah, that does seem reasonable. So, it's nothing we need to worry about, then.

'Of course not. I mean, why would we need to be worried about a rat?'

A/N (Tendra): I'm glad I've finally gotten this chapter done. Departure has been the fic that most people have wanted to see continued. You would not believe how many comments, reviews, and PMs I've gotten asking about the state of this fic. The only reason it's taken this long is because I have been having severe anxiety due to the current crisis, and I was finally prescribed a medication that manages the anxiety properly.

I have actually had the first few pages of this chapter written for some time. I started writing it way back before I caught COVID in March, but it's taken a long time to get the rest of the chapter ready. (COVID was another reason this chapter took so long. It was horrible). I still don't think this chapter is up to my usual standards for this story. I may come back and fix the pacing issues later.

Lots of people have asked why Lupin didn't notice Pettigrew on the map if he's had it. The simple answer is that the map shows hundreds of people on it at any given time, and it's not easy to find one specific name in a crowd unless you're actively looking for it. Finally, Lupin was looking at the right place at the right time to notice Peter. Harry and Tam are, of course, utterly clueless about this.

Tam has finally admitted that she fucked up when she made her horcrux. All of the hints for what went wrong are there. I'm sure you can put the pieces together if you try.

On an unrelated note, It's amazing to me that some people are missing the point of Tam's hypocrisy. Yes, she is a hypocrite. She's supposed to be a hypocrite. That's the point. Harry doesn't realise it, but he is not a reliable narrator and is in the process of being corrupted by her.

Lastly, you can join my discord server at 6YwQewK for early access to chapters like this one, as well as freedom to pester me about all of your theories.

E/N (Xgenje): I'm so angr-e about them missing the damn rat that I can't right now. Will have more next chapter.

E/N (Foadar): I nearly screamed at the screen at how Harry and Tam reacted to the Pettigrew debacle, but I will reassure you. It makes sense. Stay tuned.