Author's Note
Sunset redemption stories have probably been done to death xD but I hope this take on it isn't too similar to the others. I felt inspired to write this by the cover art. 
The Returning
"Ok, I have practiced what I'm going to say, I am prepared to accept the consequences of my actions, and...I think I'm gonna be sick and I can't do this!"
The red and gold maned unicorn was pacing furiously, hyperventilating, sweat popping up on her forehead, eyes wide with obvious terror.
"Sunset, calm down." Twilight tried getting her attention. "It's alright."
"No! It is not alright!!" Sunset all but yelled. "I am facing Celestia for the first time since I destroyed her confidence in me, turned evil, betrayed her trust and.. AAH...its too much!! It is not alright! She'll be mad, which is understandable...but what if she hates me now!?!"
"She doesn't hate you, Sunset." Twilight spoke soothingly. "She has been waiting for you, and she doesn't hate you. She is aware of all you've done and accomplished in the other world. I've filled her in. Just calm down."
Her reassurances had zero effect on Sunset, who continued to pace, pausing now and then to trot in place anxiously.
"The Princess is ready for you."
The announcement from the Royal Guard made Sunset jump. The jittery unicorn looked at Twilight in a panic. Twilight sighed.
"I'll walk with you. Come on." She followed the guard out, Sunset nervously falling into step next to her.
It was strange. Sunset could terrorize a school, steal a crown, turn into a demon, and also face down a demon. All without any fear at all, really. Yet here and now, every step taking her closer to coming face to face with her former mentor...the one she had hurt the most with her behaviour...there was a terror in her that was threatening to overcome her and cause her to faint on the spot. Having Twilight at her side helped, yes, but very little.
They were now at the heavy doors that led into the throne room, and Sunset felt her heart hammering in her chest so hard she was sure it had to be heard all over the castle. This was it. Once those doors opened she would meet her fate, face whatever terrible consequences might wait for her. She gulped audibly, and trembled visibly, her chest tightening and her lungs starting to ache.
Twilight laid her hoof on Sunset's neck for a moment. "Sunset. Breathe."
It was then the terrified mare realised she was holding her breath, and she let it out with a loud gasp.
"I...can't...do it." She managed.
"You can. I have faith in you." Twilight smiled reassuringly, before opening the doors wide with her magic, exposing the scene within.
Celestia, in all her regal glory, standing tall and straight at the base of the thrones, staring down the long walkway directly at them. Up on the platform by the thrones, stood Luna, looking every bit as regal as her sister. But it was only Celestia that Sunset zeroed in on.
A nudge from Twilight got her moving almost mechanically down the aisle towards the waiting Empress of the Sun. With each step she took, she slowed a little and hung her head lower, until by the time she arrived directly in front of Celestia, she was nearly crawling and had her snout practically touching the floor.
A long period of silence passed. Finally, gathering her courage, which wasn't much, she attempted to talk.
"P..Princess, I...I'm...I never...I..."
She was not succeeding. Tears had filled her eyes, all the crushing weight of guilt and shame coming in full force. She wanted to beg for forgiveness, like she had set out to do, but she could not for the life of her get it out.
There was no response from Celestia, or movement, and Sunset felt even worse. It took some doing to get her next words out past the tears.
"I am so sorry...I s...should never have...I...I betrayed your trust...you cared for me and y...you gave me everything, and I just...I...th..threw it back in your face and h...hurt you..."
At this point she could no longer support herself, she was trembling so badly, and she collapsed in a heap, pressing herself close to the floor and sobbing so hard she couldn't get a breath. Any attempts to speak came out as broken, unintelligible babblings. She'd known she was wrong. But it was as if it had finally sank in just how wrong. Just how horribly she had hurt and disappointed her mentor, the one who had been like a mother to her. Celestia had done so much for her, given her so much, and she had repayed it with what? A fit of rebelliousness and a mad desire for power. Her sobs grew even deeper.
She hadn't even noticed Celestia move. But suddenly she found herself wrapped in a loving embrace, clasped tightly against Celestia's chest. Somehow it both made her feel better and worse at the same time.
"I...I'm s..s..sorryy!" she wailed in repentance, clinging to her and sobbing even harder. "I...I never...I..."
"Shhh..." Celestia nuzzled her gently, attempting to calm and soothe her even as she shed tears of her own. "It is alright, Sunset...shhh...I have you. Shh."
The heaving sobs showed no signs of stopping. Sunset clung to her, desperately trying to say what she wanted, no, needed, to say and yet was unable to.
Luna and Twilight, having exchanged looks, had quietly withdrawn from the room, leaving the two alone. Celestia continued to hold and nuzzle Sunset, trying to calm her. Sunset pressed her muzzle against her former mentor's chest, no longer trying to talk, just crying instead.
A long time passed with them staying this way, until finally Sunset's stormy sobs gave way to soft crying intermingled with gasps for breath, sniffles and quiet hiccups. And then she attempted to talk.
"I...I'm s...sorry, Prin...Princess..." she choked out. "I'm s...so...s..sorry. I..."
"Shh." Celestia's voice was soft and loving. "All is forgiven, Sunset, shhh."
"B...but wh...why? I do...don't deserve it. I hurt y..you. Alot. I..." She struggled for breath and finally was able to talk a little better, though her voice was raspy from all her crying. "I never should have done that. I was wrong...I...I'm sorry. I'm sorry I turned against you. I'm sorry I hurt you. I'm just...sorry..."
Her tears started again, and Celestia hugged her closer. "Sunset, I forgive you. I forgave you long ago. I have always been here waiting, hoping you would return. Wishing that I had been able to prevent your leaving."
"But, why would you want me back? After all I did...not just here but in the other world too...how could you want me back?"
She honestly could not understand it. She had come back here expecting to be met with anger, harsh words, and any number of punishments. Instead, she was currently facing kindness, forgiveness, and love. And she didn't understand why. She'd been so horrible.
"Why...did you want me back...?"
Celestia had not let go of her, still holding her tightly. She heard the question, and smiled a little. Her voice was soft as she answered.
"Because I love you. You have a special place in my heart, Sunset. I think of you as my own daughter...you are precious to me. I will always love you, and I will always forgive you, and I promise you that no matter what you may have done, you can always come home. And I will be here, and love you just as much."
"But...but I don't deserve that..." Sunset insisted. "I did too much that was just...too terrible. I don't deserve you being so...so...nice. You should be yelling at me. Or having me thrown in the dungeons. Or in Tartarus. Something. Anything." She was growing agitated now.
"Why would I?"
"Because I was terrible! I don't deserve anything except to be punished!" She was also crying again. "I don't want nice. I don't want kind."
Celestia had released her by now and sat gazing at her. "What do you want then? For me to yell? To tell you that you are a terrible pony? Treat you as if you were a criminal?"
"But I am!" Sunset yelled. "I am terrible! And I don't want you to be nice to me! Yes, yell at me, punish me, banish me, anything!"
"And what would you have me do to you? Throw you in the castle dungeons? Banish you from Equestria forever?"
"I don't know! But its not fair that you're being so nice! So forgiving!"
She flailed her forelegs legs around in a wild gesture. She'd come back home to face consequences, yet there seemed to be none, only the offer of forgiveness and love, along with the kindness she was being shown. It was too much to process, to understand. Make sense of.
"You must not know everything! Otherwise you'd be nothing but mad! You'd be yelling, probably banish me!" She was the one yelling right now.
"I assure you, I do know. Twilight was thorough in her reports. And allow me to repeat: no matter what you have done, I still love you." Celestia sounded less like a princess and more like a mother speaking to her wayward offspring.
"THEN WHY ARE YOU BEING SO NICE IF YOU KNOW??" Sunset yelled, tears still flowing. How she had any tears left was a mystery. "You know I was as horrible over there as here?! You know I bullied and tormented and made everyone fear me?! You know I turned into a raging and rampaging demon and nearly destroyed an entire school?! You know all this?!"
"Yes." The word was softly spoken.
"Then why...are you being so kind to me...?" Sunset stared at her, no longer yelling, suddenly too tired to yell. "Its not fair. What I did was awful...I should have been punished alot worse than just fixing up the school...and definitely should be for how I treated you."
She hung her head. Celestia studied her silently. The seconds ticked by. Sunset wondered what was going through Celestia's head, but said nothing. Finally, the princess spoke.
"If punishment is what you think you should get, Sunset, then I can do that. But i would rather you accept that I love you, and forgive you, so it isn't neccessary for either of us.." She sounded like she meant it.
Sunset raised her head and stared at her, suddenly questioning the wisdom of having ranted against no punishment.
"I...I mean, I...don't really want it..." she managed. "I just...I still feel really bad. I feel like...I have to make up for it. What I did. Before I can move on. But..." she broke off, sighing.
"There is no need. You more than made up for it by the good you accomplished in the other world, and the fact you returned here so willingly." Cslestia gazed at her. "I do not think what you are looking for now is to atone for this for me, but rather yourself."
"I..."
Sunset stopped, dropping her head. Celestia wasn't wrong, not entirely. She honestly wanted the guilt to just go. Leave her alone. Yet it would not.
"I...I guess you're right." She mumbled. "I just...don't know how to let it go...I can't. I was horrible."
Celestia could see the guilt and shame still clearly written all over her face, and showing in her eyes. She thought for a long moment, still silent, then she reached out and drew the startled Sunset towards her and hugged her again, tightly. Sunset was glad to return it, but still was confused and upset.
"Listen to me." Celestia spoke softly. "I love you. I don't think this is sinking in. So let it...I love you. No matter what. In spite of anything you've done. That will never change. You are still hating yourself because you believe that you can't be loved after all this. But you can. You are not the pony you were, Sunset. You made mistakes, but you learned from them. You've become a better pony for it."
"My past is not today..." Sunset spoke quietly. "But, I still feel bad for it.."
"I know. But that is where you use your mistakes for good. Take what you learned and help others, as you did with your world's Twilight. You saved her, because you understood exactly what she was going through."
"Yeah. I guess I did." Sunset looked into her eyes. "I'm sorry. I know, I said that...but, I want to say it again...I'm sorry."
"I know you are." Celestia hugged her tightly. "And I forgive you."
Sunset felt a sudden lightness as guilt fled...for the first time it sank in that Celestia truly did forgive her, and that she no longer had to hold on to resentment towards herself. She hugged back just as tightly.
"I love you too." She said suddenly. She hadn't said it since she was a filly.
Celestia smiled widely and chuckled. "Welcome home, Sunset."
Although it had taken alot to get here, Sunset finally felt free. Finally felt completely happy. It was a feeling she had not known in a long time, and it was amazing.
Her return had been the best choice of her life, albeit a frightening one. But she didn't care. All the fear had been worth it...just to be right here, right now, in this moment, home.
