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Part 1 of Harry Potter and The Compendium Maleficiis
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2026-05-03
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2026-05-23
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Never Mess With The Black's Dark Artifacts (Sometimes)

Summary:

During the Horcrux hunt, tensions erupt and Harry clashes with Ron deep in the woods, leading Harry to abandon the mission and return to Grimmauld Place. Left alone and burdened by guilt and doubt, reflecting on the fallout of their fractured friendship. In quite isolation, he unexpectedly comes across a dark artifact that fundamentally changes the course of his life.

Or

Harry Potter starts wearing Green and Silver, lives a life free from suffering and is in love with a certain Blond haired brat.

Notes:

Buckle up your seatbelts and bring that popcorn because I feel like you guys will love this plot.

(See the end of the work for more notes.)

Chapter 1: The Locket

Chapter Text

'You don't know why I listen to the radio every night, do you?' Ron said, breathes uneven, and a harsh glare all over his face, 'To make sure I don't hear Ginny's name, or Fred, or George OR MUM' He adds, raising his voice, 'What you think I'm not listening too?' Harry snaps at him 'You think I don't know how this feels?' He's fuming, raged, hurt. 'NO, YOU DON'T KNOW HOW IT FEELS! YOUR PARENTS ARE DEAD! YOU HAVE NO FAMILY!' Ron berates him, harry looks him in the eyes for a few moments, searching for any sign of regret, but Ron stands unburdened by remorse.

He then turned his gaze to Hermione, though she looked at him with pleading eyes, then turned to look down on the floor, betrayal, Harry felt like 20 knives had stabbed his chest right that moment, so he looked at them for the last time as if it's a silent goodbye, and picks up his bag and leaves. He could hear Hermione calling for him, but he kept his gaze fixed ahead, refusing to look back.


He finds himself in 12 Grimmauld Place, conceivably because it's the safest place he could think of, knowing outside, the world is tearing itself apart, and he is the enemy’s most wanted man. Or maybe, just maybe, it’s the only place where he ever felt like Home.

Of course, he's Harry Potter, he never gets peace, getting greeted by a fuming portrait of Walburga Black isn't the most pleasant experience. 'You filthy blood-traitor! you have no right to disgrace the ancient house of Black with your presence!’ She scolded, raging, but Harry was not in the mood to put up with her, he had other things to focus on, so he just casts a silencing charm around the portrait and climbs up the stairs.

His path terminated at a singular door, it somehow managed to stand out from the rest, a set of initials carved into the wooden door “S.B”, he stood there, questioning whether he has the right to enter or not, but right now, he needed, craved, ached for the comfort of any kind of kinship, so he opens the door, the room was messier the first time he came here, when he was still Alive... Now it was neat and dusty, and the atmosphere felt almost, dead.

He laid down on the queen-sized bed, hugging the pillows where he searched for his Godfather’s scent, for any kind of warmth and security that he somehow, thought he could prove Ron wrong with it, tears streamed down his face, silently sobbing, he curled up his knees to his chest, and slowly fell asleep.


Harry woke up exhausted, dry tears now on his face gives this uncomfortable sensation of tightness, his eyes burned, but worst of all, his heart ached, for the next 5 minutes, he did not move, just looked up the ceiling and stared, he couldn't bring himself to think about last night's events.

It was pouring out the window, thunder boomed outside the place, he wondered if Ron and Hermione were okay, if they thought of him, were they searching for him? Did they take back what they said?

His thoughts were interrupted by a constant mewing out the window, he got up and followed the noise, opened the window, the cold breeze hit his skin, found a black cat shivering in the rain, mewing constantly. "You poor thing," Harry whispered as he picked up the cat and brought her inside. He quickly closed the window and wrapped her in a blanket, 'It's okay, it's okay, you're safe now' He got under the covers and held her tight, attempting to transfer his heat to her shivering frame.

He kept muttering reassuring words to the poor kitten, as if she's a helpless child seeking comfort, she slowly stopped shaking, replaced with a gentle thrum radiating from her, she was purring, Harry assumed that was a good sign, right? He decided to stay in bed and cuddle his new little friend while slowly falling back into a deep slumber.


He woke up around evening by the sound of a desperate mewing cat, 'Hi there' He picked her up and pet her, caressing her gently, she head-butts him, gently bumping her head against his chest, as of showing affection, she then started mewing, then it clicked, 'You must be famished' He then put her down and went down stairs with her following him behind.

The kitchen was dusty, he opened the pantry, trying to find anything edible, he found some dry bread and a can of sardines, he then filled a bowl with water and put them on the floor so she can eat, she sniffed the food before digging in, she ravenously ate as if someone was about to steal her meal.

Harry sat on the floor watching her eat, 'I wonder what's your story' Did she also run away from her previous family? Or was she lost? She doesn't look like a stray, she then gazed at him for a few moments as if she knew he was thinking about her, then proceeded to turn back to her meal.

'You need a name, what should I call you?' He added, maybe something that represents her? She was a black cat with bright green eyes that were impossible to miss, 'What about Cassiopeia? Cassie for short' He said, it would suit her well, with her midnight fur and jade-like eyes, a constellation would suit her well, perfect to the Black family standards, 'Do you like it?' She let out a chirrup of pure excitement, showing that she's pleased with her new name. 'Glad you do Cassie' He smiled, scratching her chin.  

 Suddenly a loud shatter was heard across the room, did someone track him down? Cassie then shifted behind Harry seeking for protection, he got up and pulled out his wand, approaching the source of the sound, Cassie following behind, he walked up slowly to the living room, and acted 'Expelliarmus!', the elf flew across the room falling on the armchair, 'KREACHER!' Harry shouted as he ran to help the elf up, 'I'm so sorry, I thought someone intruded, I forgot you were here' The elf looked at him for a moment, then glared, ‘Of course, you’re back’ He snorted, although Harry has now inherited the Black’s heritage given that he is the godson of a Black, but that did not mean the blacks accepted him, including this old elf.

 ‘Look Kreacher, for now I’ll be staying here, I need your help’ He states, Cassie hissed at the resentful elf, looks like Kreacher isn’t the only one with opinions, ‘Of course, Master’ He spat, Harry didn’t really mind, just happy to have some help.

Speaking of help, Hermione would be disappointed, knowing he was asking help from an elf, as she considered it slavery, but he didn’t really see it this way, I mean the elf was honoured to serve the house of Black, and he isn’t mistreating him in any way so it's not really considered slavery, although she would still think otherwise.

 ‘Kreacher, I need you to get some food for both me a little Cassie right here’ He glanced as the Midnight furred feline who was stretching on the dusty floor, which he should sweep sometime, ‘Anything else? Master’ Harry winced at the title, he tried asking the leather-skinned elf to call him by his given name, but he obstinately refused, so Harry just gave up, ‘No, that would be it, thanks’ Harry replied, 'Wait!' Harry called, 'Do not inform anyone about my whereabouts under any circumstance' He demands, 'As you wish, master' The elf replies, moments later, he disapparates into thin air, Harry turns back to Cassie who is now throwing herself at Harry’s legs, he picks her up, and pats her, ‘At least I got some nice company’ He smiled.


Harry decided to sweep the kitchen floor until the elf came back with his wish-list, while Cassie just laid in the corner keeping him company.

When Kreacher came back with two bags filled with food, Harry helped him put the bags on the dining table, ‘Let’s see, we’ve got Fish and Tuna for Cass, and some veggies, bread and tea leaves’ Harry looked back at Kreacher, ‘Do you mind freshening Sirius’ room until I make us dinner?’ He asked politely, ‘Of course, Master’ says the elf walking away.

 He decided to make a simple vegetable soup, since he didn’t really have many options, so he started by cutting an onion and peeling some carrots, and got to work.

His hands froze from the burning-cold water and kept using heating charms to boil the pot faster, he decided that it's a good time to start hating on the Winter season, in the end, the soup was exceptionally looking, and edible.

He poured some soup in two bowls and called the elf to eat at the dinner table, which he demandingly refused to, something about knowing his place? so Harry gave up arguing with him and put the bowl in Kreacher’s cupboard to eat there instead.

After dinner, Harry washes the dishes, cursing from time to time while his hands stung from coldness, but managed to finish unharmed, he picked Cassie from the floor and took her back upstairs into Sirius’ room.

‘What do you think will happen now, Cass?’ He wondered, by all rights, the boy who lived should be out there, hunting these fucking hocruxes, not buried beneath a pile of warm blankets crying his eyes out.

But Harry has broken, he’s entirely spent, mentally and physically shattered, crushed and forced to be part of a prophecy he never asked to be part of, ever since he remembers, he’s being risking himself for others, trying to keep everyone away from death.

He no longer wants to be a hero, a weapon, nor a symbol, he just wishes to live a normal teenage-boy life, no dark lord, no Dumbledore and no interventions.


­­For the next few days, Harry was getting dramatically bored, all he did was play with Cassiopeia, cook, eat and think about how awful his life is, which he grew really tired of doing, he wandered around the corridors looking for entertainment, when noticed a flicker of vibrant purple light seeping from under a door, as he approached, the air grew thick, carrying a powerful magical force, pulling him closer, as if inviting him to seek what’s behind.

Harry felt hesitant, but Cassie was curious, she neared the door and looked back at Harry who was still standing on the other side of the corridor, uncertainty washed all over him, she mewed, signalling him to come closer.

Despite feeling a strong sense of doubt, he approached the glowing door, wand in hand, he drew in a deep breath, releasing a heavy sigh, before pushing the door open.


It was a library.

He looked around before entering, lots and lots of shelves filled with dusty books that looked like they outlived several generations, year? No, centuries.

Harry looked around, he then saw a small orb of light, the same vibrant purple from under the door, so he got closer, and as he followed it, as it drifted to one specific book, Harry picked it up, dusting it, “The Black’s Registry of Forbidden Artefacts”.

Harry had no idea why that orb of magic indicated it to Harry, whether it’s dangerous or not, but curiosity got the better of him and decided to find out why the magic chose it, and maybe to also kill time.

Cassie was laying on the armrest of an armchair at the corner of the library, he took a seat next to her and opened the book, anything to kill time, though the pages started flipping themselves and stopped at a specific chapter, weird, Harry thought.


Chapter IV

Compendium Maleficiis

The time-space anchor of the house of Black.

The Compendium is not to turn and travel across the stream of time, but to travel across the an entirely different Parallel Universe, retreading your path from birth.

Founder

Altar Perseus Black, a Dark Wizard specialized in both metal Charming and spell crafting.

Altar has invented Compendium Maleficiis in 1943, forging it in 1954, the reason for inventing such an artefact: “The course of my life has been nothing but miserable, I have decided to change it, and relive my life under a different destiny”.

Description & Appearance

The Compendium Maleficiis is a heady, oval locket made out of obsidian and silver. Unlike other artifacts that are used for traveling through time (Past and future), relying on specific mechanics, this artifact purely relies on Dark Magic.

Observations

It has been rumoured that many wizards have taken the risk to activate the Compendium Maleficiis, and yet have not ever returned, nor have found any trace of their disappearance, they just vanished from their existence, Scholar Altar could barely document this magic as observations concerning this Locket are mostly theoretical.

Activation Ritual

 To trigger the Locket, the holder must observe these following instructions:

  • Intention- The holder and the magic within their core must intend to travel across an entirely different universe and shall not have any doubts.
  • Clasping- The holder shall wear the Locket around their neck while holding the obsidian in both hands.
  • Alignment- The holder shall open the Locket and invite the magic within it into their own magical core.
  • Speech- The holder must repeatedly say “Compendium Maleficiis fatum meum mutat” so the spell can activate the Locket.
  • The process- The Locket will suck the holder’s soul in, building a whole new universe while wiping the previous from existing. (Theoretical)

 

Possible (Theoretical) Adverse Effects:

Nausea, memory loss, loss of one or several senses (Such as sight, hearing or sense of touch).

Scholar Alter Black believes that during the shifting, your physical appearance may be harmed or lost in between traveling, because the Locket pulls your soul and may not include your physical appearance.

  

 

Warnings

This operation has low percentage certainty of success, “I, Altar will be using this this Artifact as soon as I finish documenting this, I assume all physical and temporal risks alone”.

If the displacement succeeds, the destination reality remains unknown, which may cause leading to an alternate universe with far much worse events, you shall use it at your own risk.

Altar has charmed every piece of parchment that yet to contain the name “Compendium Maleficiis” and its information to be part of every alternative Universe the locket has yet to travel, so more wizards may continue his research.

Compiler’s note (1958) – Atlas Augustus Black

I am here to inform all readers that I have searched for the name Alter Perseus Black in every Black Register, and found out that Altar has been last seen on March 19th year 1955 and has not been seen since, there were no traces other than the scrolls with his research about this locket.

 I am in complete disbelief and have reached to the conclusion that Alter may have indeed succeeded into traveling across alter universes.

Unfortunately, I was hoping for more data regarding this Artifact and I have yet been eager to learn about its capabilities.


Harry was in disbelief, first of all, did Altar actually succeed and did indeed travel into a whole new world, second of all, why did the orb of magic guide him into this? Did it somehow read him? Seen how hard his life was and thought that this would help?

He is a Light Wizard, he doesn’t do Dark magic, so why does he have this eagerness to do it?

No Harry you are not associating yourself with Dark magic, he thought, but something deep inside was hoping for a better life, what would it be like? Would I have a normal life for once?

No Harry, stop thinking about it, this is bad, not okay, and even if it is, you’ve read what Altar said, so many things could go wrong, what if Altar did not actually succeed what if his physical appearance vanished and his soul is stuck somewhere, so many bad things could have happened.

Harry closed the book shut, he will not think about this any longer, he got up leaving it on the armchair, stretched a little, and went back to Sirius’ room, with a lazy cat following behind.

He got ready for bed and stared at the ceiling while Cassie was cuddling his arm, if he couldn’t do it, that does not mean he can’t fantasize about how awesome his ‘alternative’ life could be, so he did so, replacing his previous boredom with internal fantasies, he was slowly getting addicted.


 He thought about his parents being alive, being raised by them, cuddling his mum and playing with his dad, sitting with them at the dinner table, being a family, about having normal school experiences, no fighting evil forces, just being a reckless teenager.

He felt childish for thinking like this, but it still warmed his heart, even though it’s just his imagination.

For the next week his routine consisted:

  • Waking up
  • Fantasise
  • Eat breakfast
  • Fantasise
  • Play with Cassiopeia
  • Fantasise
  • Clean
  • Fantasise
  • Eat Dinner
  • Fantasise
  • Sleep

And Harry was getting more and more impatient, the more he fantasised the more he was eager to use the locket.

 One afternoon, Harry has decided to go back into the library and read about it again, and he did, 3 times, and his most asked question was, ‘Where do I find this Locket?’ Was it even in this universe?

He searched for any kind of indication on where the Locket might be, and found nothing, Cassie mewed at him until she got his attention, ‘Not now Cass, I’m busy right now’ He replied, flipping pointlessly through the pages.

She then jumped on him covering the book with her body, ‘Cassie!’ Harry glared, she mewed at him again then looked stared at the door of the library, making Harry look her direction.

The orb of light! It was floating at the entrance of the door, waiting, ‘Sorry for ignoring you Cass, you were just trying to help’ He patted her.

Harry quickly got up and followed it, with kitty following behind, the orb was going underground, finally reaching a metallic door, he tried opening it but it was locked, he picked up his wand from under his sleeve and did a quick unlocking charm, ‘Alohamora!’, the door then opened, seriously what’s the point of locking doors anymore.

 The room he entered was filled with expensive looking objects, from gold to Platinum, Harry was mesmerized, he could feel a powerful magic within them, Artifacts! Well Dark artifacts, he could feel their heavy Dark aura, that’s where the Locket might be, but the room was ginormous, he would need days to search this storage, and Harry did not hesitate, he tucked his sleeves and started searching for it instantly.


Believe it or not, but in the middle of his 30 minutes, tiring time of searching Harry berated himself stupid, he realized he could just do an easy summoning spell to find the Locket, why did he not think of that sooner? He himself doesn’t know.

‘Accio Compendium Maleficiis!’ and in a span of 10 seconds the locket was in his hand, he studied it for a moment, it was a powerful that’s for sure, his magic shifted, as if transmitting Harry caution, it was beautiful, the way the obsidian glowed and the locket itself was so attracting, inviting, making Harry eager to open it, then doubt filled his mind, his heart raced, was he sure about this? No, no he was not. 

He was terrified, yet eager, he didn’t know what to do, so he set the Locket on the table, not taking his eyes off of it, as if scared it will run away.

He decided to think about the outcomes of this, because what he was thinking about doing was insane, and he needed to make a decision soon, and choose an option.


And that’s what he did, for the next week he kept thinking, whether it was okay what he was doing or not, weighting the pros and cons of this (Literally), but one thing, just one factor held him back.

 

He cried, cry-baby, he can’t man up and stop his tears, because, he did not really care about most things on his list other than his best friends, or rather, ex-best friends.

He thought about forgiving them, really! But he couldn’t bring himself to.

Because they hurt him too much, Ron’s words may have stabbed him in the heart, but Hermione’s silence was like pouring salt on a fresh wound, it stung, pained.

They were his only family, not by flesh and blood, but by love, though, in the end, looks like only Harry thought of it this way.

 So, he was alone, now that the only people he considered family were gone, there is no one else.

Sirius is dead, his parents, Dumbledore, no more friends, HE IS ALONE! Alone in a universe where he has to play hero even though he didn’t ask for it.

He’s already lost so many innocent lives, people who shouldn’t have risked their lives for him, and with that he is happy to stop it all. 

And honestly, if that Locket does work and he does end up in a parallel universe worse than this one, at least he’s got nothing to lose here.

And if it doesn’t work, he’s ready to do it, yes, he was scared but he’s ready, at least he will reunite with his parents, and godfather, and just end the suffering once and for all.

They might be disappointed in him for giving up, and worst of all use Dark magic in the process, but he didn’t care, he was done suffering, he wants peace.

And that really did it, he didn’t care whether he fails or not, he just wants out.

He has decided, that

tomorrow he would do it.


Harry was laying on his bed, ready to sleep, though his mind refused to quiet down, he was thinking about tomorrow, he was happy yet scared, but it’s okay right? Everything will be fine, hopefully.

‘I’m scared Cassie, what should I do?’ He looked at shadow furred cat laying next to him, she got up and surprisingly put both of her paws on his face, purring, well at least one of us is calm about the situation, he thought.

 She sniffed his cheeking tickling him with her whiskers in the process making Harry chuckle, ‘You sure know how to brighten the mood’ He smiled, picking her up, placing her on his chest, ‘I will miss you Cassie’ he scratched her chin.

 ‘We became so close this past month, I feel like I’m not ready to let go’ He added, ‘But I’m sure after I leave you will find a loving family who will treat and feed you more than I can offer, of course, I might not remember you then, but I hope you will’ Cassie looked him in the eyes for a moment, she was so cute, she then proceeded to close her emerald eyes and lay on his stomach purring, and slowly drifting to sleep.

Harry continued to pet her gently, as if scared to wake her up, he kept worrying about tomorrow’s bizarre events, until her soft vibrating purrs quieted his mind until sleep took the best of him.


He woke up the next morning, back paining, and he might know why.

A certain feline still laid on his stomach, and fearing to wake her up, he might’ve stayed still the whole night so he doesn’t disturb her.

Today is the day, the day where it will all be over, no more tears, no more pain, no more pressure.

Cassiopeia woke up, she laid her paw on Harry cheek and got off the bed, she was a shockingly smart cat.

He followed her downstairs, as he poured her some cat food and clean water, she dug right in, happy to be fed.

Harry on the other hand, was not feeling hungry, rather the opposite, feeling knots in his stomach, he was ready to throw up any second now.


After Cassie had her delectable, scrumptious breakfast, they both settled in the Library, Harry rereading the instructions on the Activation ritual over and over again, scared to mess it up.

After what felt like decades, he literally memorized the instructions word by word, Harry felt like he was ready, not quite but enough to start the ritual. 

He held the Locket in his hands feeling its Dark aura before placing it around his neck, and held the obsidian with both hands.

This is really happening, I’m excited yet scared, I just want to leave already, I just want to… Yeah Harry isn’t going to settle down.

Harry looked at an already gazing Cassie who was a few inches away from him, “Bye Cassie” He whispered, not really ready to lose her.

Harry took a deep breath, and looked at the locket before opening it slowly.

A blinding, purple flash of light erupted from the inside, It wasn’t just a soft glow, it was a powerful blast, the dark magic was strong yet welcoming.

His breath hitched, okay, he closed his eyes, embracing the magic, letting it in, ‘Compendium Maleficiis fatum meum mutat’ He said.

He could feel the magic of the Locket connect with his own, ‘Compendium Maleficiis fatum meum mutat’ He repeated, he could feel the pressure of the Locket trying to suck him in, ‘Compendium Maleficiis fatum meum mutat’ and it did.

He felt dizzy, he felt the world starting to pull away, dissolving, a weird screeching that made him fuzzy, everything is starting to blur out, ‘Compendium Maleficiis fatum meum mutat’ He whispered, this is it, he felt the Locket pulling him in, his physical presence shifting, he was unconscious.

Before the Locket could pull him all in, Cassie jumped and wrapped herself onto his left leg, sucking her in aswell.

Poof, the sound of the Locket falling on the wooden floor was louder than it should be.

They were gone.

Both Harry and Cassie.

They no longer exist in this universe.

They left.