Hello lovely readers! :) I wanted to include a short author's note to thank you for reading my story. I will really appreciate any comment you have regarding my work, but please keep in mind that my native language isn't English and I tried my best to avoid any mistakes.
Nonetheless, if you notice something incorrect please feel free to let me know so I can correct it as soon as possible and learn along the way. Thank you very much!
I hope you'll enjoy my version of a Time Travel AU with Hermione, where Regulus/Hermione will be the endgame.

12 Grimmauld Place, 1979

He never thought he would be back here again, yet here he was. In front of his childhood home, lost in thought, bringing memories to the forefront of his mind, all of them lacking warmth, the feeling of safety, happiness or unconditional love a child would need.
He was wandering about his bigoted parents, with their pureblood mania, convinced that being a Black made you practically royal.

He didn't deserve to be a part of the family anymore, so they said, not since he brought shame on the Most Ancient and Noble House of Black. The day his parents disowned him he couldn't care less, he didn't want to be a part of their plan anyway. He was disgusted by them.

But his brother, that was another story. It's great he had a brother, isn't it? He was a much better son, as he was constantly reminded.

He wished they were aware that the joke was on them now.

He threw away his cigarette, and before he could change his mind with quick confident strides he headed towards the front door and knocked.

Kreacher opened the door and looked him over with pure hatred in his large elf eyes.

"Ah, Master Sirius. Master Regulus is waiting for you in the drawing room. I believe you know the way."
"Kreacher, what a lovely welcome. I didn't know you had it in you."

Kreacher just glared at him, trying to control the comeback that was clearly withheld only out of obligation to their family, after all Sirius was still a Black by blood, he couldn't outright disrespect him.

They entered the threshold and Sirius followed him to the drawing room, where his little brother was sitting in one of the leather armchairs, with a tumbler of Firewhiskey in his hand. Not so little anymore, he was already 17 he thought.

"Hello, brother."
He seemed to be deep in though about something, he looked up from his glass and glanced at him, he had an expression on his face he showed when he was weighing his options, like when he was trying to solve an Arithmancy equation.
"Regulus." he nodded. "Your letter was rather cryptic."he stood in the middle of the room, with his arms crossed, brows furrowed.
"Kreacher, leave us please."he addressed the elf in the corner. "I'll summon you if we need anything."he waited until the elf left, then cast a Muffliato for good measure and a charm to signal if somebody was eavesdropping or approaching the room. Nobody else was in the house to his knowledge, but one couldn't be safe enough these days.

"Well, I couldn't very well tell you in a damn letter what I wanted to say. Fancy a drink?"
"No, thanks. I'd prefer if you just got on with it."
"Did you practice Occlumency as I asked you to?"
"I am sure I am not as good as you, I didn't have the "privilege" to study under dear Aunt Bella's tutelage, but I am adequate I believe. Why?"he observed him, examined his posture, he was fidgeting with his wand, his mouth twitched then he opened it and closed it again, like he was trying to find the right words.
"I cannot reveal anything I want to say until I am certain that I cannot be compromised. May I?"he stood and raised his wand, about to perform Legilimency on him to test exactly how good he was.
"Are you bloody insane? What if you see something I don't want you to see? he took a step back, trying to put some distance between them.

They started to reconcile their relationship a couple of months ago, when Regulus approached him confessing that he wasn't as loyal to the cause as their parents believed, but he still hasn't earned his complete trust, yet if he wanted to be honest with himself.

"Are you scared Sirius?he smirked.
One would think if he was sorted into bloody Gryffindor, he would be reckless and cocky enough to just go along with it.
He might still possess some self-preservation. Good, they will definitely need that in the long-run.

"What?! No!" he exclaimed, "but that doesn't mean I want you to invade my mind."
"Look, you don't know what you are up against. Not really. I need to share this information with you, but I need to be sure that he cannot get even a glimpse of our plans if you are captured. It's too important. He cannot discover what we know." he didn't need to specify who he was.
"That's the question, isn't it? Know what exactly?"
"Sirius, we do not have time for your stubbornness, Mother and Father can be back any minute. You'll let me use Legilimency on you, or you know where the door is. You can just forget it and leave."
"Alright, alright. Just give me a second." he took a deep breath, closed his eyes and tried to burry all his recent memories of Regulus and their conversations, his letters, anything related to their interactions from the present into the back of his mind, organized in neat piles of books on bookshelves. Then he concentrated more on the task and made sure to have all the books which contained Order information strongly sealed from another prying mind in his head.
"I am ready." he sighed.
Regulus made eye contact, stepped closer and raised his wand. Up this close Sirius can clearly see the dark circles under his eyes.
With all honesty being sleep deprived during war was not that uncommon, but something told him that there was another matter bothering his brother. The hair on his neck prickled.
"Legilimens" he entered his mind smoothly with great precision.

If Sirius didn't know he was searching among his memories, he wouldn't have a clue that there was somebody else in his head. He was more than good, he was brilliant at this.
Regulus tried to find a weak point in his system, but he couldn't see anything interesting, only useless everyday activities and ridiculous thoughts about nonsense.

"Good job brother. You are not half bad." he smirked," but keep in mind the Dark Lord won't give you a second, he will invade your mind without hesitation with much force. It will be painful. You need to keep up your walls even if they torture you." his mouth turned down in a scowl.
"And believe me when I say, they will do just that if you find yourself in one of his cells." his jaw clenched, his was holding his wand so tightly his knuckles turned white. He turned towards the wall, thinking just how many of those tortures does he need to witness until it will be finally over? At least they can move on to the next step now that Sirius is ready.

"So what now?" asked Sirius eagerly, he couldn't phantom what else Voldemort could have over them, which would make their fight against the Dark side even more difficult than it already was. He started pacing the room, Regulus was hiding it well, but he knew him better. He was agitated and that made him anxious about what he was about to say.
"Do you know what a Horcrux is?" Regulus finally blurted it out.
Sirius abruptly stopped and stared at his brother wide eyed, his mouth slightly agape. Whatever he thought he would say, this wasn't it.
"No.." his face got paler considerably with each second passed.
"Please don't tell me he created one." he whispered, even though he knew they couldn't be heard by anybody.

He didn't need an explanation about what it was, even if he was disowned he was still a Black, he grew up in this house and he had information on all kind of dark arts he was supposed to be interested in according to his parents. Only by thinking about what someone had to do to create such a vile thing as a Horcrux, he shivered and could feel bile coming up his throat.

"I am afraid so. He desires to be immortal, if someone gets to him, he wanted a solution to be able to come back." he cast down his eyes and turned to pick up his tumbler of Firewhiskey and finished his drink with one gulp. He seemed so tired of this situation in that moment,
"What do we do now? Do you know what it is? Or where he keeps it? How do you even begin to destroy something like this?" he asked question after question, his brain suddenly going overdrive with the possibilities. This was a game changer for the Light side.

"Leave that to me. I wanted to talk about something else entirely. I got a hold on an item which could help us as a last resort if I..well, if I die destroying it.." Regulus stepped closer to him, with uncertainty in his stare. He looked so young right then, he reminded him of a time when they were only innocent little boys playing in the backyard. He wished they grew up differently.
Regulus seemed desperate for his trust, his eyes dilated, staring directly at him. "Do you trust me?" he asked.
"I..Yes Reg, I do."
"Good." He relaxed considerably at that. "Do you know what this is?" he removed a golden chain from under his black bottom up shirt, with an hourglass pendant attached to it.
"Is it what I think it is? You are absolutely insane, Reg. Where did you even get this to begin with!?
"Firstly, calm down. Secondly, I have my ways and honestly the less you know the better." He sighed.
"Now, I want you to listen carefully. Exactly 2 days from now, I will go to the location where the Horcrux is hidden and I will try to obtain it and destroy it as soon as I can. I know from Kreacher that there are many obstacles in the way to have my hands on the item, and it is rather possible that I die doing this mission."

"What the hell!? How can you be so calm about this!?"
"Would you shut it for a minute!? Let me explain or Merlin help me I'll ask somebody else who can keep his shit together!"
He went to pour himself another glass of the amber liquid and downed it in one gulp once more. He needed something to relax his nerves. He was planning this for so long, there was no turning back now.
He waited until Sirius calmed down a bit, then he faced him again to continue telling him his plans.

"As I was saying, it is rather difficult to get to the Horcrux and I will probably die, it would be foolish of me to think that I can succeed the first time."

"The first time? Oh Merlin. You want me to use the Time Turner, don't you? So in case you don't..in case you…" he wouldn't say it out loud, he just couldn't voice what will probably happen to his little brother.

"Yes. I researched it, basically everybody advise against changing anything in the past or to be seen when somebody uses a Timer Turner, but for fuck's sake we don't have a choice in this. We never had. This is a risk I am willing to take. We must do it this way Sirius. So..will you use the Time Turner for me if it's necessary?"
"Damn it, Reggie." He looked defeated, staring rather down at his shoes than to directly at him.
"Are you in or not?" he snapped.
"I am in. You know I would do anything for you, you are my brother. I just wish we would have more information on Time Turners and time traveling, these devices are extremely rare, and these are only prototypes yet. Nobody knows for certain what will happen."
"I don't have a future anyway if the Dark Lord continues to live. This is not a life, it's hell on Earth. It's just going to get worse and worse and you know it."
"How will I know if you..if you don't succeed?"
"I'll command Kreacher to find you. Until then the Time Turner will be hidden in my bedroom. Nobody else will find it. If my calculations are correct using this Time Turner you will be transported back here tomorrow, to my bedroom. Father and Mother are not here tomorrow, so if you suddenly appear they won't suspect a thing. Now you must leave." he commanded.
"Regulus." he gulped.
"Yes?" he muttered.
"Please make sure I don't need to use the bloody thing, alright?"
"I will try my best, brother." he smirked then. He needn't worry about this. It's all going to work out just fine. It needed to be fine.
"Take care of yourself." He genuinely smiled back then.
"You, too." But Sirius already apparated away without hearing what he said. It's going to be fine.

12 Grimmauld Place, 1997

She couldn't sleep. She knew she should try and go back down to the others, but it was impossible for her mind to rest tonight. So much was at stake now. They weren't at school anymore, they were alone and couldn't even ask for help…now that Dumbledore was dead.
She decided to wander around the house, she was restless and she wanted to be productive during their hiding until they come up with a plan.

Maybe, just maybe she could find something useful which would put some light on the whole R.A.B mystery.

Who could he be? Or she, on that thought.

"I have stolen the real Horcrux and intend to destroy it as soon as I can. I face death in the hope that when you meet your match, you will be mortal once more…" she thought.

Was this person successful at the end? Did he die by the hands of Voldemort? Did he knew there were more than one?Who knew. She had so many questions and she hated when she was in the dark.

She was walking upstairs and after a couple of minutes she finally reached the topmost floor of the old family home. The corridor was dark and eerie, but she continued towards the first door nonetheless, Sirius' bedroom.
If it wasn't obvious by the nameplate on the door that said Sirius, Hermione could have easily guessed that it was his.

The room was spacious with a large bed that had a carved headboard, a tall window with long velvet curtains, and a candle chandelier. The walls of the room were covered with so many pictures that it was barely possible to see the wallpaper.

Many of the pictures had a Permanent Sticking Charm on them so his family could not take them down. His room was decorated with Gryffindor banners and colors to show his difference from his family and most probably to irritate his parents to no end.

On top of that he had pictures of muggle motorcycles and bikini-clad Muggle girls. She would have liked to see her charming mother's reaction to that.
On second thought, maybe not. Who knows what kind of punishment she deemed reasonable for that.
What a vile woman, and she didn't even meet her in person, just her portrait. She shivered at the thought.

There was also a picture of the four Marauders: himself, Professor Lupin, Harry's father James and Peter fucking traitor Pettigrew.

She must show this to Harry first thing in the morning, he will love to see this. She tore down the part where Pettigrew was and put it on fire with a non-verbal Incendio.

He doesn't need to see that.

It was very dusty suggesting the room had not been used for a long time just as the rest of the house. Earlier that day she tried to tidy up the downstairs area by using all the cleaning and house-holding spells she remembered from Mrs. Weasley, but it still wasn't perfect in her opinion.

Here she got rid of the dust but otherwise left everything untouched.

After half an hour of looking around, she only found one object with great value.

Sirius kept a letter from Lily about Harry, James, Pettigrew, Dumbledore and somebody named Bathilda.
Bathilda Bagshot perhaps? Probably.

With it was a picture of Harry on a toy broomstick with James, she couldn't be sure who else was on it because it was torn in half.

The end of the letter was missing, too. Could it be that Snape took it for some reason? But why?

"It could still be somewhere in the room.." she thought.

It wasn't useful of course in any way to destroy Voldemort's Hocruxes, but it will put a smile on Harry's face at least. She couldn't remember when he smiled genuinely for the last time.
She also found many books and papers strewn about the room, but nothing to help along her research, nor she could recover the missing parts of the letter and picture.

She decided to probe the second room on this floor as well and then to slowly make her way downstairs inspecting every other room just in case.

When she reached for the doorknob she suddenly stopped, routed to her spot, her eyebrows shooting up and her eyes going wide.

A sign is hung above the threshold which read: Do Not Enter Without the Express Permission of Regulus Arcturus Black.

"R.A.B."-she gasped.

She quickly recovered from her shock and flung the door open and peered inside.

The room was slightly smaller than Sirius's and the Slytherin colors of emerald and silver were everywhere, draping the bed, the walls and the windows.

Th Black family crest was painstakingly painted over the bed, along with its motto Toujours Pur. Beneath this was a collection of yellow newspaper cuttings, all stuck together to make a ragged collage.
Regulus, Sirius's brother she assumed because he never mentioned him to her, must have been a strong supporter of Voldemort.

As she stepped closer she could see that the collage was made of newspaper cuttings about his idol, the Dark Lord himself.

Could he have been their R.A.B, if he was a Voldemort supporter? A Death Eater even? She couldn't know for sure.

She continued her search but she didn't find much so far, an old Slytherin Quidditch team photograph adorned one of the walls, featuring Regulus, the Seeker, sitting in the middle of the a crowd of Slytherin students.

Regulus was instantly recognizable in the middle of the front row: He had the same dark hair and slightly haughty look of his brother, even though he was smaller, slighter, he wasn't at all less handsome than Sirius had been.

He looked as the perfect picture of a pureblood heir, with his aristocratic features.

She wandered if he really was their R.A.B from the note they found in Salazar Slytherin's locket.

Was he a little bit like Malfoy?
Was he very young when he joined Voldemort if he had the Dark mark on his arm?

If yes, did he have a choice or was he pressured to support the cause by his family?

Did he ever regret becoming a Death Eater and secretly tried to bring down Voldemort?

His name certainly matched.

She needed to ask Harry in the morning if he knew more about him from Sirius.

The drawers of a desk had been taken out and the contents had littered the floor. Another sign pointing towards the obvious, Snape must have gone through all of the rooms, too just as they suspected.

"Aparecium" she whispered to try to reveal if there were any secret messages, hidden markings, or anything invisible in the room thanks to Concealing Charms.

To her huge surprise a book fell from one of the bookshelves.

She quickly stepped closer and inspected it, she didn't want to be a victim of a nasty curse if she could help it.

It was a black leather diary.

She grabbed it up from the floor and opened it, but to her disappointment it was empty.

It cannot be simply empty, now can it? It wouldn't have fallen down from the shelf, there must be a reason why this notebook reacted to her spell.

She started to turn the pages to see if there was something written on one of them at least and in her excited hurry she caused herself a paper cut on her finger, accidentally smudging a little bit of her blood on the pages.
She quickly healed it and decided to try to examine the diary a bit more.

"Specialis revelio" she muttered trying to see what kind of spells were performed on the diary.

"Now this is interesting alright.." She whispered to herself, her brows furrowed, her eyes narrowed and turned the book around and around. Nothing special on the outside, just the black leather cover.

On the other hand there were several very complicated and complex transfigurations and something else, dark magic done on this "diary" because in reality it wasn't a diary at all.

What was it then?

"Reparifarge" she said to see if she could transfigure the object back to its original state.

For a moment nothing happened at all, but then suddenly a bright light emerged from the diary as it started to shift back and grew warm in her hands.

Hermione tried to release it form her grasp, but it was impossible, it was glued to her hand, she just couldn't let it go.

As the seconds passed, the diary started to morph more quickly and by the moment she could clearly see what she was holding, she was utterly panicking.

Her skin turned ashen on her face, her hair prickled on her neck, her breathing was coming out in short gasps and she could feel a cold sweat appearing on her body.

Her shoulders were tight and she was holding onto her wand like her life depended on it.

It was a Time Turner.

"No.." She muttered at the moment the light emerging from the Time Turner vanished and she could feel that the world around her started to spin with sickening speed, taking her to some other time she had no idea about.

It was horrible, it felt like the worst Portkey travel she ever had if she wanted to compare it to something, she felt nauseous, terrified and so damn confused.

She didn't have time to think it through though because abruptly the spinning stopped and she collided ungraciously
with the hardwood floor scraping her knees and one of her palms in the process.

She was on all fours and concentrated as much as she could to keep down whatever she had for dinner before.

"Oh I am so going to be sick." She thought taking long deep breaths, closing her eyes.

When she opened her eyes once more after a couple of seconds she realized that she was in the same room, in Grimmauld Place but this time she wasn't alone.

First her eyes landed on a pair of very expensive looking dragon hide boots, then she lifted her head and realized there was a wand pointing at her face.

"Who the fuck are you and how did you manage to get in here?" He hissed in a low voice.

Hermione didn't want to believe her eyes.

"Regulus?" She whispered.

Regulus's eyes widened at that, then narrowed and scowled at her. This girl in front of him seemed to be about his age with dark brown hair cascading down on her back in loose big curls. She was pale and small, slightly trembling, blinking rabidly with visible beads of sweat on her forehead.

And most importantly, he did not recognize her at all.