The first week of summer at number twelve, Grimmauld Place was a return to haven for Harry. It was the time in his life to experienced a true, chaotic, and loving home during the holidays, a fact that he had enjoyed immensely last year as well. The house, under Kreacher's newly enthusiastic and Ariana-centric care, was slowly shedding its gloomy, oppressive atmosphere. The mornings were filled with the easy banter of Sirius and Remus, the afternoons with exploring the dusty, secret-filled rooms, and the evenings with shared meals where laughter, not fear, was the dominant sound.
Ariana fit into this new family dynamic with her usual quiet grace. She was a calm, steadying presence, often found reading in a corner of the drawing-room while the others engaged in more boisterous activities. Her primary project was the Black family library. It was a treasure trove of ancient, often dark, magical knowledge. With Sirius's permission, she began the monumental task of cataloging, purging the most dangerous cursed tomes, and restoring the valuable ones. It was a task she undertook with a librarian's zeal and a scholar's precision.
One afternoon, while Harry and Remus were busy in the small, magically-expanded attic room, Ariana sought out Sirius. She found him in the study, staring at the vast, sprawling tapestry of the Black family tree.
"Sirius," she said, her voice pulling him from his reverie. "I need to speak with you privately. On a matter of strategic importance concerning the war effort."
Her tone was so serious, so formal, that Sirius immediately gave her his full attention. He gestured to a chair. "Of course, Ariana. What is it?"
"With Voldemort's return," she began, dispensing with pleasantries, "he will require a base of operations. A secure, well-warded location within Britain from which he can rally his followers and plan his next moves. He will not choose a random location. He will choose a place of power, offered by one of his most loyal and high-ranking followers."
Sirius's expression darkened. "Lucius Malfoy."
"Precisely," Ariana affirmed. "Malfoy Manor is the most logical choice. It is well-protected, politically significant, and Lucius's public denial of his Death Eater past makes it the perfect, unsuspected headquarters."
"And what can we do about it?" Sirius asked, a frustrated anger in his voice. "We can't just storm the place. Fudge would never allow it."
"We do not need to storm it," Ariana said, a cold, sharp light in her eyes. "We need to legally repossess it."
Sirius stared at her, utterly bewildered. "Repossess it? What are you talking about?"
"I have spent some time in your library studying the ancient laws of pure-blood houses and the marriage contracts of the Noble and Most Ancient House of Black," she said, her voice as calm as if she were discussing a potions recipe. "You, Sirius, as the last male heir, are the undisputed Lord of the Black family. Your authority, in matters of family law, is absolute."
She continued, her logic unfolding like a legal argument. "Your cousin, Narcissa, married Lucius Malfoy. Her marriage contract included a significant dowry provided by the Black family fortune to the Malfoy family. A dowry which, I have discovered, included the deed to the land upon which Malfoy Manor was built, effectively making it a Black family property gifted through marriage."
Sirius's eyes widened as he began to see the shape of her plan.
"Similarly," Ariana went on, "your other cousin, Bellatrix, married Rodolphus Lestrange. Her dowry was also substantial."
"What's your point, Ariana?" Sirius asked, his heart beginning to pound.
"The point," she said, her voice dropping to a low, conspiratorial tone, "is that ancient pure-blood law contains clauses for the revocation of such contracts. As Lord Black, you have the right to dissolve the marriage alliances of any who have brought dishonor upon the House or acted against its interests. Bellatrix Lestrange is a convicted, escaped mass-murderer. Narcissa Malfoy is married to a known, if unconvicted, Death Eater who consorts with the man who murdered your own new family members. You have more than enough grounds."
She leaned forward, her eyes gleaming with a ruthless, strategic brilliance. "You have the legal, magical, and moral authority to revoke both marriage contracts. And in doing so, you can legally reclaim their dowries."
The full, devastating impact of her words hit Sirius. "Reclaim the dowries… that would mean… I would own Malfoy Manor."
"You would," she confirmed. "And you would gain control of the entire Malfoy family vault at Gringotts, as it would be seized to repay the cash portion of the dowry. You would effectively bankrupt Lucius Malfoy and evict him from his own home."
Sirius looked stunned, then a slow, predatory grin spread across his face. It was the grin of the old marauder, the troublemaker. "That is… the most beautifully vicious thing I have ever heard."
"The timing, however, is critical," Ariana cautioned. "You must not act now. To do so would alert Voldemort that we are aware of his presence there. You will allow them to continue using the manor. Let them feel safe. Let them establish their headquarters, bring in their followers, store their dark artifacts. We will let them build their hornet's nest."
"And then?" Sirius breathed, captivated.
"And then," Ariana said, her voice like ice, "at a moment of our choosing—perhaps after Voldemort has made his public reappearance and the Ministry can no longer deny the truth—you will enact the revocation clause. With a single, legal move, you will seize his home, his fortune, and his base of operations, throwing the Dark Lord and his entire inner circle out onto the street. It will be a blow so devastating, so humiliating, it will cripple their entire organization before the war has even truly begun."
The plan was not just a military strategy; it was a masterpiece of political and economic warfare. It used the pure-bloods' own archaic, prejudiced laws as a weapon against them.
"There is one more thing," Ariana said, her tone shifting slightly. "The Lestrange dowry. When you reclaim it, you will also seize control of their Gringotts vault."
"It's yours," Sirius said immediately. "Whatever's in it."
"I am not interested in the gold," Ariana said. "But Bellatrix, as Voldemort's most trusted lieutenant, was likely entrusted with an object of great importance to him. An object I believe is currently stored in her vault. I will need access to it."
She was, of course, referring to Hufflepuff's Cup.
Sirius Black looked at the young woman before him, a girl who had just handed him the legal and financial equivalent of a dragon. She had armed him with a weapon more powerful than any curse.
"Ariana," he said, his voice full of a new, profound respect. "Consider it done. I'll have my solicitors at Gringotts begin drafting the paperwork immediately. We'll have it ready to strike the moment you give the word."
He stood up and walked to the window, looking out at the quiet London street. Lucius Malfoy was sleeping peacefully in his grand manor, utterly oblivious to the fact that a fifteen-year-old girl had just legally and financially destroyed him, and was simply waiting for the perfect moment to let the axe fall. The war had many fronts, and Ariana Dumbledore had just opened a new one, right in the heart of the enemy's treasury.