A/N: Special thanks and credit to my dear friend Kitty. Both for her beta-ing help and her idea of how to defeat Voldemort.

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"Remember, you are forbidden to speak to anyone about anything that happened here today and will not report to my mother about anything I do or who I have seen," he ordered Kreacher, who had spent the entire conversation staring at Sirius in utter disgust but had remained silent as ordered. "Take us home."

"Yes, Master," Kreacher bowed low, Side- Apparating them home; and taking one look at the articles covering his walls, Regulus gave into the desire he had felt for the last few weeks and tore them all down.

Even as the torn pieces of parchment fluttered down all around him and Kreacher looked up to him worriedly; he couldn't find it in himself to care and as much as he had never expected to see his room again, he found that he couldn't stay in it a moment longer either. "Go to your room and stay there until it is time. Come get me in six hours, I will most likely be in the library. And not a word to Mother."

He couldn't hear his mother's heavy footsteps, though he did not know if that was because she was still in her bedroom weeping after his father's untimely death or because she was asleep and as such took care to not let her hear him move around.

It wouldn't do for his mother to discover what he was doing, she was so deeply set in her ways that she would not understand why he had changed and perhaps even try to stop him, something he could not let happen.

Despite tearing through the library, he found no more than the mere basics of information on the subject in the time he had and could only hope his brother had had more luck as Kreacher came to get him.

Potter was leaning in almost the exact same spot as he had before, though Sirius didn't appear to have returned yet so he dismissed Kreacher before approaching.

Having learned from his previous visit, Regulus stopped far enough away that the wards would not actively try to stop him.

"Did you learn anything?"

"Nothing useful," Regulus admitted. "You?"

"Nothing," Potter answered. "But my father believed that destroying them beyond repair might work."

"That might work when destroying them one by one, but not when Sirius wants to destroy them all at once."

"If he has voiced that much then that means he already has a plan and is just looking for confirmation that it will work," the sheer confidence in Potter's words was just one more piece of confirmation that Regulus truly didn't know his brother very well; but he didn't comment as Potter suddenly straightened and glanced off to the side moments before Sirius Apparated inside the wards.

"How did it go?"

"I have been granted access to the vaults of both the Malfoys and the Lestranges," Sirius said. "Neither of you found anything, have you?"

"No, how did you know that?"

"One of the only books containing detailed information about Horcruxes is called 'Secrets of the Darkest Art', one I know is kept at Grimmauld Place. It is being kept in the study so you would not have found it in the library."

"A book that our parents wouldn't own," Potter admitted. "But why doesn't Arcturus have it?"

"He does, but ripped out several pages of magic even he deemed too dangerous."

"Including the Horcrux ones," Regulus realised. "How can you be certain that Father has not done the same thing?"

"Because I have read it as a child. Walburga made it her mission to make me see the so called beauty of dark magic and made me read everything she could think of."

"Right," it clearly hadn't worked but it did mean his brother had an idea of what to do. "And you remember how to destroy them?"

"I'm fairly sure, though it wouldn't hurt to have that book for confirmation."

"Then I will see to it that you'll get it. What else did Grandfather say?"

"Not much, he still wishes to remain neutral in the war; though he has given me full consent to move freely as his Heir," Sirius pulled a golden ring out of his pocket; though it took Regulus a moment to recognise it as his father's ring.

"Didn't Grandfather take that from Father after he disinherited him?"

"Apparently it should have been given to me when I turned twelve as I'm the Heir but Orion didn't. I have no interest in wearing it, but it will give us full access to anything we might want," he dropped the ring back into his pocket. "If we still wish to make it to Gringotts today, we should leave now."

"The longer we wait, the more chance there is that the Dark Lord might figure out what we are doing."

"I agree," Potter stepped out of the protective wards. "You are sure they won't alert either the Malfoys or Blacks of our visit?"

"They shouldn't," Sirius retrieved two cloaks from his house and handed one to Potter. "But I'll be sure to mention it, just in case. Make sure you put your hood up."

Understanding his brother's motive to hide exactly who they were from the wrong people, both Regulus and Potter followed Sirius' lead before they placed a hand on his outstretched arm.

Moments later they were standing in front of Gringotts and he followed as the other two strode through the entrance and along the marble hallway to a counter about halfway into the building.

Regulus had no idea why they skipped all the empty counters before the one they seemingly picked in mute unison, but did not mention it as they came to a stop and Sirius stepped forward.

But the words he spoke were not ones Regulus recognised, a string of guttural rattling noises that were rather rough on the ears, though the Goblin behind the counter immediately looked up and answer in kind as a smile crossed his lips.

"Well met, brother Sirius," he spoke in English, giving a small incline of the head in a clear display of respect, one met and returned by Sirius. "What brings you here today?"

"Official Heir business," Sirius reached into his pocket. "Lord Black has ordered me to inspect the vaults of those who are suspected of dishonouring the House."

"I did not think you cared about that," the Goblin raised an eyebrow as Sirius placed the Heir ring onto the counter.

"I would not Gornuk, if it weren't for a matter concerning my heart's family as well."

"Fortius Quo Fidelius," the Goblin nodded in agreement, eyes sliding to Potter momentarily before they returned to Sirius and he slid the ring back to him. "Which vaults would Heir Black like to investigate?"

"Lestrange and Malfoy," Sirius glanced down at the ring. "Aren't you supposed to check that thoroughly?"

"You are the most honourable wizard I know, you would not deceit me. Your companions?"

"You know my brother James," Potter spoke something in the same gibberish Sirius had, though whatever he said made the Goblin raise an eyebrow and Sirius shake his head fondly.

"I shall pretend you meant to tell me you hope gold shall flow freely and business shall flourish," the Goblin shook his head. "Your Gobbledegook is terrible as ever, brother James."

"Sorry, that's what I meant," Potter looked at Sirius. "What did I say?"

"Nothing I can repeat," Sirius laughed before sobering. "I don't know if you have ever met Regulus Black?"

Pitch black eyes met Regulus' and it suddenly occurred to him that the goblin was friends with his brother and that was why they had chosen him for their business.

"Good afternoon," he greeted the creature after a moment of silence, normally his parents had done all the talking when dealing with the goblins but did not think any of their interactions were something he should repeat.

"Yes, afternoon," the dark eyes turned away from him again to look at Sirius in question; who shrugged a little helplessly in return.

"We deal the hand we've been given, anything to protect our heart's treasure."

Regulus was not sure what the words meant, but they seemed to appease the goblin as he rose to his feet. "You know what you are looking for?"

"I have been given an indication," as his brother followed the Goblin without hesitation both Potter and Regulus followed and a cart ride later had them standing before a vault.

"Malfoy vault, I shall wait outside for you to finish," the Goblin opened the vault for them, stepped aside so they could pass.

"Thank you Gornuk," Sirius stepped into the vault.

"How will we recognise if it's here?" Potter softly asked once they were out of earshot from the Goblin.

"You should be able to recognise it the moment you see it."

"How?" raising an eyebrow as Potter simply began searching without further instructions, he turned to his brother.

"Look around if you see any books, we'll go from there," accepting the vague instructions, Regulus turned left; looking around the surprisingly empty vault. There were no layers upon layers of gold and relics as there were in the Black vault and he wondered if the Malfoys truly were as rich as Lucius had always claimed to be.

"Found it," Sirius' soft voice called out several minutes later; holding up a thin book with a cloth.

"A book like you thought it would be," moving to his brother's side, Regulus looked at it. "How can you be sure it is what we were looking for?"

"There is a strong darkness in it," Potter answered. "I can recognise Riddle's magical signature in it; though it's faint."

"How..."

"It's like in the cave; focus on the book and you might be able to sense it as well."

Following his brother's instructions, Regulus could indeed feel a faint pulse coming from the book.

"How could you recognise it so easily?"

"We are more attuned than you are," the only reason Regulus didn't bristle at Potter's words were because his tone wasn't condescending but simply matter-of-fact.

"Right, Lestrange vault?"

"Yes, we're searching for something large and round there. Might help narrow down the search," Sirius left the vault again and turned to the Goblin; one Regulus now knew was called Gornuk. "We've found what we were looking for here."

"May they burn for their deceit and theft. Would Heir Black wish for us to seize the vault?"

"Not yet," Sirius put the book into his bag. "I first need to finish gathering the evidence I have been set out to collect before acting. It would not do for them to run before we are ready."

"Very well, Gringotts shall wait for your word before seizing the vault from their control," Gornuk bowed slightly. "Shall we move to the next?"

Regulus' stomach turned as they travelled much deeper underground, the sense of being underground never having sat well with him, but he made no comment as they were once again admitted into the Lestrange Vault without a problem.

This vault was crammed from the floor to ceiling; silver armour, coins and potions scattered everywhere as the shelves were much too small to contain everything.

Seeing something that looked like skin, Regulus stepped forward for a better look, hitting a piece of gold in the progress.

Immediately it duplicated itself and a sharp burning pain rushed through his feet. "Merlin!"

Staggering back, he bit back several curses as the coin he had hit kept duplicating several times before coming to a stop and he saw Potter scramble back as well, but Sirius was standing in the middle of the vault and must have touched at least a few items, yet nothing multiplied at his touch and he looked at them confused.

"Probably set a Geminio and Flagrante curse on everything," Potted mused as he made sure to not come anywhere near anything in the vault.

"Then why doesn't anything react to him?"

"It's probably set against intruders," Sirius mused as he moved further into the vault to search for the Horcrux. "But they wouldn't want to be burned if they visited their own vault so made sure to allow themselves unchallenged access."

"And since you are the Heir to the family, you can enter untroubled as well," grumbling, Regulus rubbed his toe as he scanned the vault with his eyes only. "Up on that shelf in the very back is a round cup. It's both big and round enough to be what we're looking for."

He couldn't help but grumble a little more as his brother climbed a mountain of coins to be able to reach the shelf and removed the cup without a problem.

"This is it," he called as he wrapped the cup into a piece of cloth and put it into his bag before climbing down again. "I can't sense anything else, you James?"

"No," Potter moved forward enough to help Sirius over a pile of Knuts, being careful not to touch anything.

"Then we are done here, unless either of you has another idea?"

"No, let's regroup back at your house to determine our next step," Potter helped Sirius down and they both moved to Regulus again.

"We are done here, Gornuk," Sirius waited until the vault had been closed again. "I need not remind you how important it is to keep Lord Black's investigation to yourself for now?"

"A Head of House's business is not for us to discuss," Gornuk' dark eyes met Sirius'. "Nor is that of the Heir. May your investigation go well and your intent flourish."

"Thank you, Gornuk. If all goes well, you will see the result soon enough," the Goblin's words did not seem to alarm Sirius half as much as Regulus and he simply returned to the cart so they could return to the entrance.

They didn't speak as Sirius Apparated them back, inside the wards to Regulus' surprise but he didn't comment on it as Sirius and Potter made their way inside and his brother placed the items on his kitchen table.

"How do you plan to destroy them?" Regulus asked as he looked at the three displayed items.

"I'd like to have a look at Secrets of the Dark Arts to be sure, but I think a chain Fiendfyre would work well enough. And although it won't do anything to Riddle himself, it would have the added benefit that should he have hidden another Horcrux somewhere, it'll be destroyed as well."

"Then I will retrieve the book so that we can be sure," Regulus decided.

"We will get ready to destroy them when you have returned, then," Sirius agreed and with a short nod, Regulus made his way outside to Apparate back home.

It was just as he had found the book that a burning sensation in his left forearm took his breath away and he knew the Dark Lord was summoning him.

"Kreacher!"

Even as the trusty House-elf appeared, Regulus could hear his mother calling for him and he hurriedly pressed the book into his hands. "Bring this to Sirius and tell him to destroy them. I will be in the perfect position to take him out for good in ten minutes."

"Yes, Master," Kreacher disappeared with a loud crack and Regulus hurried to grab his robes, waving his mother off as she came out a side chamber.

"Sorry Mother, but I must go at once," not waiting for a reply, Regulus hurried outside and Apparated to the Dark Lord's summoning.

"You are late," Bellatrix snapped at him as he arrived and he glanced at her warily while fastening his mask.

"I was delayed by Mother," it wasn't unusual for his mother to complain any time he left, worried for him since his father's death and Bellatrix knew her well enough to only sniff in disdain but make no other comment as they made their way to their respective places in the circle.

While he had just been grateful to be a part of the Dark Lord's inner circle at all, he now wished he was just a little bit closer so it would've been easier to take the man out.

As the other masked people took their places around him, he forced his mind to clear as he knew the Dark Lord would be able to sense any hostile thought and bowed along with everyone else as he strode into the room.

"Someone has betrayed one of our own," as always, the Dark Lord's voice lured people in, though Regulus no longer felt the same pull he used to have and tried to squash down his revolt at knowing what the man truly was.

"My Lord?" as usual, it was only Bellatrix who was brave enough to speak up as the others cowered in fright and Regulus focused on taking even breaths to keep his heart rate normal.

"Mere hours ago, Wormtail was discovered and arrested by Auror Potter. Anyone care to tell me how that could be?" There was no mistaking the anger in his voice and involuntarily, Regulus flinched along with everyone else.

"Did the fool betray himself?" Snape drawled from Voldemort's left.

Regulus had envied his supposed friend for rising in the ranks so quickly in the mere year he'd been in the Dark Lord's service longer than he himself, but now he just felt disgust at ever having wanted to be like him.

"I do not believe that is the case. Someone sold him out," Voldemort's red eyes slid over them one by one, making them all duck lower. "You will..."

A horrific scream snapped Regulus' head up just in time to see the Dark Lord being engulfed in flames; fire bursting out of the man and spreading through the room with a roar that stopped his heart dead cold.

The faint familiarity of his brother's magical signature behind the magical flames immediately told him the Dark Lord must have had a Horcrux on him that Sirius' spell was now destroying, taking the man himself with it as Fiendfyre did not differentiate between human and object, burning everything in its path.

Masked people screamed, the fire vaporising them effortlessly and although he had been ready to sacrifice himself to take the Dark Lord out before; he still found himself running for the doors with Bellatrix.

"Expulso!" Bellatrix' shriek exploded the doors, annulling the magic keeping them closed and they scrambled away from the horrific screams behind them.

"Move!" she hissed as she shoved him to the side and as he stumbled to keep his balance his heart hammered in his throat as roaring flames burst through the corridor before them and although Bellatrix desperately raised a shield in protection, she was no match for the roaring flames as they surrounded her.

Closing his eyes so he wouldn't have to see her burn, her terrified screams pierced through him before they abruptly cut off and his last thoughts as the heat of the flames rushed towards him was that at least his brother had managed to destroy the Dark Lord and that was worth dying for.