Sirius Black strode purposefully through the cobblestone streets of Diagon Alley, his footsteps echoing with a subtle air of authority. His tall, lean figure was adorned in impeccably tailored black robes that clung to his form, a stark contrast to the vibrant, bustling marketplace around him. The fabric flowed around him like a dark river, whispering of wealth and privilege.

Upon reaching the entrance, he paused, casting an imperious glance at the goblins who guarded the bank. His slate-gray eyes bore a cold, calculating glint. His lips curled into a faint, haughty smile, one that suggested he was well aware of the power his name carried in wizarding society.

"Open the doors," Sirius commanded with regal air, tilting his chin upward. His voice carried an aristocratic lilt that demanded immediate obedience. His words were as sharp as the edges of a finely forged blade, and they resonated in the grand marble hall of Gringotts.

The goblin on duty, though normally unyielding, hesitated for a mere fraction of a second before reluctantly turning to the massive keyhole and inserting a gilded key. The doors creaked and groaned as they slowly swung open, revealing the labyrinthine depths of the bank's interior.

Stepping into the dimly lit interior of the bank, Sirius's presence commanded attention from the moment he crossed the threshold. The goblins scurrying about the cavernous hall gave him sidelong glances.

As he walked deeper into the bank, his footsteps echoed with each confident stride, reverberating through the cool, dimly lit corridors. He approached the counter where a goblin clerk waited, regarding him with shrewd, calculating eyes.

"Good day, I am here to access the Black family vault," Sirius greeted with icy politeness, his voice carrying an air of expectation.

The goblin, while acknowledging Sirius's identity, was not about to bend the rules. With a stern expression, he demanded, "Identification, please, Mr. Black. The key to the vault, if you please."

Sirius's lips curled into a sneer, his steely gray eyes flashing dangerously. He remembered his brother Regulus's words well. Suppressing his rising anger, in a voice dripping with condescension, he leaned in closer, his voice low and chilling.

"Do you know who I am?" he hissed, every word dripping with arrogance. "I am Sirius Black, scion of the Most Ancient and noble House of Black. My family has been a cornerstone of this bank for generations. The House of Black has paid a substantial sum of money to keep this institution running smoothly. It would be a great pity if, suddenly, those generous donations were to cease." His tone was laced with a subtle threat, a promise of repercussions that would befall Gringotts should they dare to defy him.

The goblin hesitated, clearly aware of the dangerous glint in Sirius's eyes. The Black family, notorious for their mastery of Dark Magic, was not to be trifled with. Swallowing his pride, the goblin motioned for Sirius to follow him.

The journey in the cart was anything but pleasant, with various twists and turns that threatened to turn his stomach inside out. Finally, after what felt like an eternity of winding turns, the cart shuddered to a halt at the entrance of the Black family vault. The goblin retreated to a safe distance as Sirius approached the vault, his heart pounding with excitement and dread. With a deep breath, he inserted the key into the lock, and with a resounding click, the doors opened.

With the massive vault door now wide open, Sirius entered the vault. The chamber was cavernous and dimly lit, with rows upon rows of ornate, enchanted heirlooms and treasures that stretched far into the distance. The air was thick with the scent of old parchment, gold, and the faint trace of dark magic.

Sirius knew that the book he sought, as per Regulus's instructions, would be at the far end of the vault. His keen eyes scanned the rows of chests, statues, and relics as he made his way deeper into the heart of the vault. His steps echoed in the vast chamber, and every flicker of the dim light created eerie shadows that danced along the walls.

It didn't take long for him to spot what he was looking for – a chest with a large, ornate 'B' engraved on it, standing out amidst the rest. He approached it with purpose, his gloved hand resting on the lid as he examined the intricate designs that adorned it.

However, as he attempted to open the chest, it refused to budge. Frustration flitted across his face briefly, but then realization struck him. He belonged to a family obsessed with blood purity, and this chest was undoubtedly protected by blood magic. A wry smile tugged at his lips as he recalled that the Blacks had a penchant for using their own blood as a key.

Muttering a small "Diffindo" under his breath, he pricked his ring finger with the tip of his wand. Small droplets of his blood fell onto the lock, sizzling as they made contact. The chest responded to the offering, and with a soft click, it finally opened.

Inside the chest, nestled amidst layers of velvet, lay the worn and tattered book that Regulus had described. Sirius's face twisted in disgust as he reached for the book, careful not to touch it directly. He pulled out a handkerchief from his pocket and gingerly wrapped the book in it, securing it within the folds of his coat.

The journey back seemed to pass in a blur. Sirius moved swiftly, his steps echoing through the cavernous chamber, the precious cargo in his coat weighing heavily on his mind. Finally, he made his way out of the bank, where Regulus was waiting for him.

Sirius approached Regulus with a sardonic grin playing on his lips. "Well, dear brother," he remarked, "it's been quite fun, hasn't it? Playing the perfect little pureblood, following in the family's footsteps, and all that."

Regulus merely dismissed the comment with a curt nod, his eyes filled with a mix of impatience and curiosity. "Cut the theatrics, Sirius. Did you retrieve the book or not?"

Sirius's grin faded slightly as he reached into the folds of his coat, pulling out the handkerchief-wrapped tome. He held it out to Regulus, feigning hurt as he said, "Of course, baby brother. You doubted me? You really should have more confidence in your older brother."

Taking the book, Regulus regarded Sirius with a hint of skepticism. "It's not about doubting you, Sirius. It's about the gravity of this mission."

Sirius's expression turned more serious as he leaned in closer, his voice lowered. "Tell me, Regulus, why did it have to be me going into that wretched vault? You're the rightful heir, after all."

Regulus sighed, his eyes clouded with the weight of their family's history. "It needed the blood of the Heir to open, Sirius."

Sirius raised an eyebrow, a mixture of frustration and confusion in his voice. "But Reggie, you are the current heir. I was blasted off the tapestry, disowned. Why did I have to go through all of this?"

Regulus's response was unwavering. "True, you may have been blasted off the tapestry, and perhaps to the sacred Twenty-Eight families, you're no longer the heir. But goblins are different. They don't follow our wizard customs. To them, you are still the Heir of the House of Black, and that's all that matters when it comes to opening that vault."

As Regulus held the ancient Black grimoire in his hands, Sirius couldn't help but feel a mixture of conflicting emotions. He was torn between disgust at being associated with the Black family and a strange sense of pride that surely had his ancestors rolling in their graves.

"Reggie," he began, his voice tinged with curiosity, "what exactly are you looking for in the Black grimoire? And how did you even know it was in our vault?"

Regulus, his fingers delicately turning the pages of the tome, paused at a particular page and then turned it toward Sirius. In golden letters, the page read, "Magicae Essentia Vacua." He answered, "Our Uncle Alphard had always had a penchant for collecting antiquities. He told me he had acquired the Black grimoire from an Egyptian merchant, who had stumbled upon it in some forgotten corner of the world. Who do you think got the Gryffindor sword that's in the Lestrange vault?"

Sirius' eyes widened excitedly at the newfound information. "That sword is real? Why haven't I seen it?"

"Yes, brother, the sword is real. Now to the matter at hand, please," Regulus said, aggravated.

Clearing his throat, Sirius continued with his questioning, "But why the Black grimoire? Every magical family has their own grimoire. You could have borrowed the Malfoy's, for instance. Our families are tightly knit."

Regulus shook his head, a faint smile playing at his lips as he explained. "You see, Sirius, the Black lineage goes back much further than the Malfoys. While the Malfoy line can be traced back to William the Conqueror, the Black family can be traced all the way back to Alfred the Great. The Black grimoire contains knowledge and secrets that have been amassed over centuries, far surpassing any other family's grimoire in both depth and breadth. It's a treasure trove of ancient magic, rituals, and spells that can't be found anywhere else."

With a nod of understanding, Sirius faintly smiled as he asked his brother, "Is that it? Is this what's going to bring Voldemort to his knees?"

Regulus returned the smile, though his expression was tinged with a hint of seriousness. "Yes, Sirius. This is the beginning of Voldemort's downfall. But we have much planning ahead of us before we can put this knowledge into action. Lucius and I will make ourselves known when we have gathered all the information we need. We are going to make sure he doesn't come back by any means."

As Regulus turned to depart, Sirius couldn't help but express his concern. "Be careful with that grimoire, Reggie. It's full of dark magic."

Regulus turned back with a sinister smile, his eyes glinting with mischief. "Is it not what runs in our veins, brother? Blacks are synonymous with dark magic. We don't make dark magic; we are dark magic." And with a faint pop, he disappeared, leaving Sirius to chuckle softly, "touché, little brother, touché."

Contrary to popular belief, Regulus had never purposefully dabbled with Dark Magic. Sure, he had been close at times, mainly because he was an avid reader, a bit of a swot, as Sirius would playfully tease when they were young. All the books in Grimmauld Place had something to do with Dark Magic, and growing up, they were the only books available to him.

However, with the Black Grimoire in hand, Regulus was prepared to go to any lengths to protect his goddaughter. Even if it meant delving into the depths of Dark Magic, he was willing to tread that dangerous path, for he knew that desperate times called for desperate measures. And that's where Lucius' help became crucial.

Regulus apparated directly into the entrance hall of Malfoy Manor and walked with determination to the study. He knew that Narcissa and Lucius had been studying several books on blood wards and family magic, and their expertise would be invaluable for his plan.

Opening the study door, he entered with purpose, pulling the Black Grimoire from his coat and approaching the table where Narcissa and Lucius were engrossed in their research. Without preamble, he slammed the ancient tome down onto the table, causing the books and parchments to jump with the impact.

Narcissa looked up with surprise, her elegant features momentarily contorted with shock. "Regulus, what on earth..."

Lucius, always the epitome of composure, raised an eyebrow as he examined the book. "Well, what's this about, Regulus? I thought you said only the Heir could access it."

Narcissa, who had been silent until now, burst out laughing as she looked at Regulus, and said, "No, he didn't."

Regulus smirked and replied, "Oh yes, he did. He even reminded them of how our family kept the bank running."

Lucius, now growing annoyed, asked, "Who are you talking about?"

Narcissa, calming down, said "Lucius dear, it was Sirius who retrieved it. That boy has always been reckless and a bit dramatic. Still is, mind you, must be the Gryffindor in him."

Regulus, humorously, added, "That's right, Lucius. Sirius, as much as he hates to admit it, received Pureblood training just before he got disowned. He has manners, the postures, and the attitude. When he walked through the doors of Gringotts, Sirius wasn't just Sirius Black; he was the Heir to the Most Ancient and Noble House of Black."

Lucius couldn't help but chuckle at the thought of Sirius using his Pureblood upbringing to access the Black vault. "Well, I must say, Regulus, your brother is quite resourceful when he puts his mind to it. What do you plan to do next?"

Regulus didn't waste any time. "This is the Black Grimoire, the oldest grimoire in the whole world and one of the most potent repositories of Dark Magic knowledge in existence. I need your help, both of you."

Narcissa and Lucius exchanged a quick glance, their expressions shifting from surprise to curiosity. Narcissa spoke first, her tone laced with caution. "Regulus, you know we've distanced ourselves from that world. We have Draco to think about; you have Hermione to think about, for Salazar's sake."

Regulus nodded, understanding their concern. "I'm not asking you to embrace Dark Magic for the sake of it. I'm asking for your expertise in family magic and protective wards. This book contains a ritual that can create an impenetrable shield around Hermione, around Godric's Hollow. With it, we can trap the Dark Lord and drain him from the inside, even a baby will be able to kill him if we succeed, which we will."

Lucius leaned forward, his fingers tracing the elaborate patterns on the cover of the grimoire. "Are you sure you want to do this? You could die in the process, and I don't want your brother banging on my door."

Regulus's eyes bore into Lucius's, his gaze unwavering. "Yes, I know what I'm getting into, Lucius, because if we don't act, if we don't stop Voldemort, he'll come for Hermione and I'm not letting that happen. If I have to die, so be it. If that means she will be safe, that's all I care about. And don't pretend you wouldn't give your life for Hermione. I've seen you with her, and you clearly care for her."

Smirking lightly, he continued. "You wouldn't want to anger your wife, would you, Lucius? After all, Hermione is also Cissy's goddaughter, and being careless about our goddaughter's safety would mean you would find yourself facing the infamous Black temper. And Cissy throws some nasty hexes when she's angry, if I recall correctly. Now, let's get down to business."

Sirius had always harbored a deep hatred for Dark Magic and anything associated with it. However, after a conversation with his brother Regulus a month ago, he found himself in the Potter library, flipping through a book titled "Samhain Ultra Obumbratio."

Before he could delve further, the book was abruptly snatched from his hands by his uncle Charlus. Sirius had never seen his uncle so angry.

Charlus, his expression dark and stern, demanded, "Sirius, what are you doing with this book?"

Slightly taken aback by his reaction, Sirius replied, "I'm assisting Reggie with an investigation, Uncle Charlie."

Charlus's eyebrows furrowed in disbelief. "Investigating what, Sirius? Why are you specifically looking at this book? You've always stated your aversion to Dark Magic."

Sirius took a deep breath, realizing he needed to explain himself. "I'm well aware of what I've said, Uncle, and I still stand by it. However, Regulus and I retrieved the Black Grimoire about a month ago. There was a chapter in it that caught Regulus's attention; it was called 'Magicae Essentia Vacua.' He believes it holds the key to defeating Voldemort, as it seems destroying the Horcruxes might not be enough for my younger brother."

Charlus was astonished by this revelation. "What Regulus is attempting involves a complex potion and a powerful spell," he stated solemnly, holding the potions book in his hands.

Sirius's eyes widened with curiosity and concern. "Uncle Charlie, how do you know about this specific branch of Dark Magic?"

Charlus grimly answered, "The Potters have always excelled in potion-making throughout history; it's a part of our family legacy. While Potions can be used to help people, they can also cause significant harm. Potions are temperamental; their nature can be influenced by the intentions of the person brewing them. It's not just about the ingredients; it's about the mindset of the potion maker. Whatever the intention of the person brewing the potion is, it will indirectly affect the potion itself."

Sirius began to grasp the gravity of the situation. "So, what Regulus is planning involves a potion and a spell?"

"Ultimately, it's a spell that Regulus is seeking, but it requires a specific potion, 'Essentia Magi Arcanum Divellentis,' from 'Samhaim ultra obumbratio,' and a spell from the Black Grimoire, 'Divellere Magicae Abstrahendum Aperire.' Do you recall the Salem witch trials?"

Sirius's curiosity was piqued by the unexpected question. "Salem trials? You mean the witch trials in Salem, Massachusetts?" he replied. "We briefly studied them in History of Magic, but I didn't pay much attention."

Charlus nodded gravely, his expression serious. "What exactly do you know about the Salem trials, Sirius?"

Sirius scratched his head, recalling the bits of information he had retained. "Well," he began, "the Salem witch trials were a series of witchcraft accusations and trials that took place in 1692 in Salem, Massachusetts. A group of muggleborn girls claimed to be possessed by witches and accused several people of practicing witchcraft. The trials resulted in the execution of 20 people, mostly women, and the imprisonment of many others."

Charlus then leaned in, his eyes fixed on Sirius, and asked, "Do you know how the accused witches were killed?"

Sirius nodded in response, answering, "They were killed by being burned, weren't they?"

Charlus sighed, his expression growing even graver. "Yes and no. They were accused of practicing witchcraft and faced horrific executions, but the most favored method was burning at the stake. Do you know why?"

"Sorry, Uncle Charlie, did you just imply," he began slowly, his voice tinged with disbelief, "that the witches weren't killed by the fire?"

Charlus nodded solemnly. "Exactly, Sirius. What truly transpired is that they perished due to a spell that Regulus is trying to locate." Charlus leaned forward, emphasizing the gravity of his words.

He continued, "The Salem trials extended for a year and a half, which, believe it or not, provided ample time to brew this potion. Unless the person brewing it was an expert, it took a staggering nine months to prepare."

"The potion was strategically poured in a carefully selected area where the witches were to be burned. Twice every month for the initial seven months, the land was exposed to this deadly concoction. Then, to seal their fate, the spell from the grimoire Regulus possesses was recited during every full moon for the final three months of the process."

Sirius shuddered at the calculated cruelty of it all. "And when they were finally placed on the stakes," he ventured cautiously, "what happened?"

Charlus concluded with a somber tone, "When the witches were bound to the stakes, it triggered the entire mechanism. It effectively severed them from their magical cores, rendering them powerless and no longer witches. The fire merely consumed their mortal forms."

'Divellere Magicae Abstrahendum Aperire' was designed to breach the magical defenses surrounding the target's core, allowing the weakened magical essence, courtesy of the potion, to be extracted. When combined with 'Essentia Magi Arcanum Divellentis,' it created a devastating and irreversible effect on the target's magical core."

Sirius felt a shiver run down his spine as he realized the gravity of what they were discussing. "So, Regulus intends to use this combination to weaken Voldemort's magical core and extract it?"

Charlus nodded gravely. "Yes, Sirius, but you must understand the risks involved. This is incredibly dangerous magic, and it can have dire consequences if not executed perfectly. The smallest mistake could result in catastrophic failure and eventual death."

Sirius clenched his fists. "I understand the risks, Uncle Charlus. But we can't allow Voldemort to continue his reign of terror. Hermione's safety, and the safety of so many others, depends on us stopping him."

Charlus placed a reassuring hand on Sirius's shoulder. "I admire your courage, Sirius; do make sure your brother receives this information before he decides to proceed on his own. I wouldn't want Hermione to lose her beloved godfather."