Hi! This is a request from AbbyLove, a really awesome reader and writer here on fanfiction, and she wanted this to be a fic with Sirius helping Hermione get over Ron to the song "Somebody That I Used to Know" by Gotye. I'm pretty sure you've all heard it, it's pretty popular, so you know that I do not own it, and neither do I own Harry Potter.
So...this might be a little challenging since there isn't like another person helping someone out in the song, but I think I can do it! Here we go! ^^

Now and then I think of when we were together
Like when you said you felt so happy you could die
Told myself that you were right for me
But felt so lonely in your company
But that was love and it's an ache I still remember

Hermione sighed, blowing a strand of hair from her face as she sat cross-legged in the middle of her flat, neatly wrapping all of her fragile decorations in newspaper. She'd been consumed by the tedious task for over three hours now, keeping her mind on only the wrapping. If she found her mind straying, she would instantly turn it to the colours of the gnome she was wrapping, or the memory of what was going on when a certain article in the newspaper she was using to wrap had been written. Now she had packed away the very last of her belongings into boxes and she had nothing left to keep her mind off of the one and only person she had been trying to keep her thoughts off of by doing anything else she could think of.
Ronald Weasley, her ex-fiancé.
She shook her head as she eased herself up into a standing position, looking across the boxes and boxes of items she didn't really need. Most of it would be going off to Ron's new flat, anyways. She had been kind enough to wrap and pack it for him.
She made her way to the kitchen and poured herself a cup of tea as she thought. She blew away the strand of hair that had fallen from her bandana once again.
Hermione had just been so sure that Ron had been the right one for her. He'd always told her how happy she made him and, the majority of the time, she felt the same way. She had been happy, too. Sure, occasionally it felt as though something were missing, but she had loved him, and, now that he had left her, she almost missed that feeling of missing something in her relationship, rather than having no relationship at all.

You can get addicted to a certain kind of sadness
Like resignation to the end
Always the end
So when we found that we could not make sense
Well you said that we would still be friends
But I'll admit that I was glad that it was over

Hermione was slightly startled by a knock at her door, though she'd known he'd be coming. She was relieved to see Sirius step through the door with that constantly cheerful smile plastered across his face. Being around Sirius could cheer anyone up. Especially Hermione, as he had promised her that she could live with him, free of charge. Ron and she had both been paying for their shared flat (and since Harry had moved in with Ginny, they had already been struggling) but on her own there was no possible way for her to pay the rent.
"Sirius," Hermione said, almost silently, stepping into him and wrapping her arms around him.
She could feel his chest rumbling as he chuckled. "Hello, love."
Hermione had always fancied Sirius a little bit, even when she had been with Ron, however guilty that made her feel. She had almost been relieved when their relationship had ended, if only because it opened her up for Sirius. But that in no way meant she didn't miss Ron dreadfully. They just hadn't been compatible, they hadn't fit together. They just weren't right, and the only thing keeping them together were their addictions to their feelings of love.

But you didn't have to cut me off
Make out like it never happened
And that we were nothing
And I don't even need your love
But you treat me like a stranger
And that feels so rough

Hermione pulled away from Sirius and gave him a smile.
"How're you holding up, then?" he asked, crossing his arms across his chest and leaning up against the counter.
Hermione shrugged. "Alright, I guess. I miss him."
A cold look came across Sirius's face. "He's being a real git, not even coming around anymore. He hasn't visited his own mum in weeks. He'll only see Harry, though Harry's the only one who will see him. We're all angry at him for what he did to you."
Hermione only smiled. "It's really alright. We just weren't right for each other."
"But he has no right to be avoiding you like this," Sirius replied.
Hermione shrugged again. "He should be over in a few minutes to pick up his things. I packed all of them up for him."
Sirius shook his head. "You're too good, Hermione. Well, I suppose I should start moving. What should I take first?"
"Er..." Hermione replied, moving through the boxes. She found one, handed it over, and Sirius disapparated to Number 12, where Hermione would soon be taking up a residency.

You didn't have to stoop so low
Have your friends collect your records
And then change your number
I guess that I don't need that though
Now you're just somebody that I used to know
Now you're just somebody that I used to know
Now you're just somebody that I used to know

While Sirius was gone, Hermione began stacking up the boxes of Ron's old belongings so they would be easier to get to. She was contemplating just taking them to his new flat herself, when there was a crack and a knock at the door.
Hermione's stomach erupted in butterflies and she almost felt like crying. Ron...
She pulled the door open, preparing for the sight of him, when she was shocked into tears.
A concerned expression came across Harry's face.
"Hermione?" he asked, kneeling next to her. "What's wrong? Did you hurt yourself?"
Hermione shook her head, clutching herself tightly around her waist. "No," she said through her tears. "No. I was just...I was so excited to see Ron again, but he..."
"He sent me instead," Harry finished for her. "I'm sorry, Hermione, but Ron doesn't want to see anybody. He rarely leaves his flat."
Hermione took several deep breaths, Harry watching her with his hand on her shoulder. She took one final shuddering breath and wiped her eyes on the palm of her hand. She shook her head and licked her lips.
"I want to see him. I'll bring him his things."
Harry shook his head. "You don't know where he lives."
"Of course I do," Hermione replied. "He lives on Wallis Street."
Harry shook his head. "He only told you that."
Hermione was confused. "Then...were does he live?"
Harry shook his head. "I'm sorry. He doesn't want you to know."
Hermione's breath left her in a gust and she sunk down into a chair, trying to catch her breath.
Harry sat down next to her and placed a hand on her shoulder. "I'm so sorry, Hermione. I've been trying to change his mind, convince him that he should see people again, but he won't listen to me. I'm sorry."
Hermione's breath was coming in shuddering gulps. "I don't blame you, Harry," she whispered. "Can you just...take Ron's stuff and go? I think I need to be alone."
Harry nodded at her sympathetically and placed all of Ron's belongings under a shrinking charm. He placed them in his pocket and disapparated.

Now and then I think of all the times you screwed me over
But had me believing it was always something that I'd done
And I don't wanna live that way
Reading into every word you say
You said that you could let it go
And I wouldn't catch you hung up on somebody that you used to know...

Sirius helped her bring all of her things back to Number 12, and they were done by around seven, though they still had unpacking to do.
Hermione decided to save it until the morning. She got into the shower at around eight and simply stood in the hot water, thinking about how happy her relationship with Ron had made her. That's what she focused on - she couldn't bring herself to think of the down-sides.
She finally got out of the shower at 10, the water long ago having turned to freezing, and went to her room, climbing over boxes and digging through her bag to find a pair of pajamas. She left her hair wet and uncombed and climbed into bed, too tired to do anything else.
But lying in bed allowed her mind to wander.
She resorted to her favourite way of comfort - reading. Wrapping up in her duvet, Hermione dragged herself into the library to find a book to lose herself in until she could no longer keep her eyes open.
She entered the room and sleepily made her way to the bookshelf, picking a random book and curling up in the first chair she saw to read it.
She gasped and stood right back up, dropping her book and letting her duvet slip to the ground when she noticed her chair was already occupied.
Sirius only laughed. "Hello, love. You should probably go to sleep."
Hermione's heart rate soon slowed down again and she shook her head, sinking into the chair next to his. "I can't," she replied. "If I stop controlling my thoughts...well, I'm scared of what they'll turn to."
Sirius sighed. "Maybe it's about time you do think about these things. Maybe it'd be good for you."
She shook her head. "I don't see how."
"Come on," Sirius said. "What's something about Ron that really ticked you off?"
"I don't want to think about it, Sirius," she replied, standing.
But Sirius only grabbed her hand lightly and pulled her down, to Hermione's surprise, into his lap.
"What's something about your relationship with Ron that made you angry?"
"I..." It didn't take long for something to come to mind. "I was always wrong."
"Good! Explain."
"Everything I did or said was the wrong thing to do or say. It was always my fault and never his."
"That's terrible," Sirius grumbled. He was surprised to find himself becoming more and more angry with the ginger kid. What was wrong with him, hurting his Hermione like that? Wait - his Hermione?
"I guess it was," Hermione replied absently, completely unaware of the fact that Sirius was currently going through a complicated thought process as he tried to help her sort out her own emotions. "But what was really awful was that I always had to try and decipher what he was trying to say. He'd say something completely harmless, but I'd be thinking about it all day until I finally realised he was insulting me, and by the time I figured it out I wouldn't want to bring it up."
Sirius shook his head. "Simply terrible. How about this - what's the absolute worst thing about dating Ronald Weasley."
Hermione shook her head and stood up. "I don't want to think about him anymore. I'm going to go to bed."
"Hermione, it's been almost two whole months," Sirius said. "You can't go on living like this. Come on, love. Talk to me."
She shook her head. "No. It's too awful to talk about. I won't talk about it."
"Hermione, you have to -"
"Fine!" she exclaimed. "You really want to know? The worst thing is that I still love him, even though I caught him whoring around with Lavender Brown!"
The library was silent.
"I'm sorry..." Sirius finally said, quite awkwardly. "How come you never told anyone?"
"Because they would all just think I was a fool for staying with him," Hermione replied. She was crying, quite hard, too. She shook her head, her face scrunched up, trying to contain her tears. "I couldn't leave him. I loved him."
Sirius crossed the room, wrapping her in his arms, if only so he wouldn't have to see her cry like this. She clung to him tightly, bawling into his chest. He muttered soothing words to her and tugged his fingers through her hair.
She soon fell limp and Sirius helped her to her bedroom, tucking her blankets around her. He kissed her forehead, though he was sure she was most probably already asleep.

But you didn't have to cut me off
Make out like it never happened
And that we were nothing
And I don't even need your love
But you treat me like a stranger
And that feels so rough
You didn't have to stoop so low
Have your friends collect your records
And then change your number
I guess that I don't need that though
Now you're just somebody that I used to know

She wished she was just sleeping. She wished she wasn't having these dreams, the ones that pointed out every flaw in her and Ron's relationship, showing her every reason why Hermione should no longer love him. It was the most difficult thing to endure.
But towards the end of her dream, her mind decided to point out something very interesting. She may not have Ron...
...but Sirius was completely free.

Somebody...

The next morning, Hermione was the most refreshed she'd been since the breakup. She was ready to confront Ron if it ever came to it, and she was completely ready to move on.
Sirius gauged her mood when she came down for breakfast, confused by her sudden change in vigour.
She greeted him with a cheerful, "Good morning, Sirius!" and he gave her a cautious, "Hello, love," before pouring her a cup of tea and setting breakfast in front of her.
"Hmm, smells great!" she replied before digging in. She hadn't realised it had been so long since she'd last actually eaten something of substance and in larger quantities than a few bites to keep her going. Looking down, she noticed she'd lost quite a bit of weight. She scolded herself by eating more. She had seconds and then thirds before she sighed and sat back in her seat.
Sirius was smiling at her, quite pleased that his exercise the night before had worked. She would be good as new in no time.
...
2 Months Later

I used to know
That I used to know

Hermione came down stairs, skipping gently, giddy from the events of last night. She hadn't removed her sun dress and had slept in it the night before, but that was alright. She sat down at the table and grinned at Sirius as he served her breakfast.
He kissed her gently before taking his seat across from her.
"Good morning, love," he said happily, tearing into his own breakfast. "Sleep well?"
"Amazingly," Hermione replied. "I don't know. There's something different about your bed that makes everything ten times more comfortable.
Sirius laughed. "Is that so?"
Hermione nodded and began eating, enjoying the way the ring on her left ring finger glistened as she cut at her food. It would surely catch everyone's attention.
"Molly invited us over to Sunday night dinner," Sirius said as she finished and moved to pick up the daily prophet.
"Oh, really?" Hermione replied. "That's great! I miss everyone over there."
Sirius nodded. "Are you going to tell them all tonight?"
Hermione nodded. "I guess I'll have to. I know they probably won't approve since it's only been two months since we started dating, but we've known each other for much, much longer."
"Six years," Sirius said, nodding.
"I'll just use that argument if anyone disapproves," Hermione said.
"There's, er, one more thing," Sirius said, clearing his throat.
"What is it?" Hermione replied, barely looking away from the newspaper.
"Ron's going to be there."
Hermione nearly choked on her pumpkin juice, but she shook her head. "Great. He should know, too." She nodded a few times in a sort of anxious movement. "He should know, too."
Sirius gauged her expression and hoped this night wouldn't ruin everything.

Somebody...

They arrived at the burrow at around noon and were all greeted very warmly. Hermione had turned her ring around so it wouldn't catch very much attention, and she kept that hand in Sirius' the majority of the time.
Like Sirius had said, Ron was present, and he was watching the two like a vulture. Because he hadn't been around much, he probably only barely knew Hermione and Sirius were dating, let alone that they had been growing more and more serious. He glared when he caught Hermione's eye, and she smiled and turned away.
He was in the past, now.
At supper, they were all chatting merrily, when people began to stand up, one by one, giving announcements, as was the custom. Any big news was shared here.
Ginny and Harry stood up and announced that they would be having their first child. After hugs and congratulations, Remus stood and announced that he had found a cure for a very deadly muggle disease. Arthur announced a promotion, Fleur announced that her family was moving closer, and finally it was Sirius and Hermione's turn. They stood, still holding hands, but he held her right, and Hermione raised her left. Grinning, she rotated her ring so everyone could see it.
Fleur and Ginny cheered, Remus and Harry high fived Sirius, and Molly nearly leapt across the table to engulf Hermione in a hug. This hadn't really been the reaction she'd expected - she'd expected a lot more explaining and tears than this. But the only one not reacting in a positive way was Ron.
And he didn't matter. Because now, he was somebody that Hermione didn't care about.
Now, he was a stranger.

Now you're just somebody that I used to know

Sorry it was so late, AbbyLove! It was kind of a long one…
I hope you all enjoyed it! This was kind of fun to write. ^^