Sunset and Twilight enter the throne room and sees Celestia. The fiery-haired unicorn walks closer to the throne and begins to talk.
"Princess Celestia, last time we see each other I was a bad pony who disappointed and betrayed you, nothing that I could say is enough to justify all I did, but now I'm here, a different pony, better than I was before, humbly begging for your forgiveness."
Celestia said nothing, she leaves the throne and stops in front of Sunset, before the unicorn could say anything, the princess hugged her with their forehooves and wings.
"I've missed you, was not your fault Sunset, all you did, was not your fault but mine." Said the princess.
Sunset broke the embrace and looked into Celestia's eyes.
"What do you mean? I betrayed you, stole Twilight's crown, throw off all you taught me, is all my fault, I had nothing and you gave me everything, a purpose, your guidance, care, love, and ..."
Celestia touches gently the unicorn's face and says:
"I'm the true culprit here Sunset. Allow me to tell you a story that I should tell you a long time ago. Everything began almost thirty-one years ago when I dated a young stallion named Night Light..."
"WHAT??? Do you date my father? How in name of Equestria this is possible?" Screamed Twilight before the princess could speak more.
"I'm just speaking about this Twilight, if I could finish the story you will understand." Said, Celestia.
"Sorry princess is that I'm never thought of you in this way." Said Twilight apologizing.
"Anyway, almost thirty-one years ago I meet your father in one of my escapes of the castle. Was an ordinary Monday, the Sun already was in the sky, and I was bored, nothing important to do all day and I decided to take a break and simply walk around. I go to my room and said to not interrupt me unless Equestria's fate is in danger, so I used a simple illusion spell to look like a normal unicorn and teleported myself to the Canterlot streets."
"I was trotting distractedly when I hit somepony and we both fell. I look at him and he was so handsome that my heart skipped a beat. I apologized, and he asks what a so beautiful place like me is making in a girl like this, I laughed and my muzzle makes a snort, I love him since then. We spend all day together, talking, laughing, I felt so free like I don't feel since I was a filly."
"Near the sunset, we were in the Canterlot gardens when we first kiss, I felt so alive, a heat in my chest, butterflies in my belly, I didn't feel like that in almost a millennium. We said goodbye and from this day we were dating. Every free time that I had, we spend together, so two months after we first meet, I tell him who I really was. At first, he has upset, I lied to him but he felt that all we had lived couldn't be a lie, and forgives me. We stay together for eleven joyful months, but this couldn't last forever, I was the ruler of Equestria and my subjects come first then my happiness. One day, after we, er, 'spent the night together', I broke up with him, if he stays at my side, someday he could be a target of the enemies of the kingdom. They could use Night Light to hit me, force me to give up the throne."
"He understood and forgiven me, I broke his heart, but he smiled at me and promised to not tell nopony about us. About a year after, I heard that he was married to a young mare named Twilight Velvet."
"I still don't see the connection between your story and me, princess"
"I agree with Sunset, princess." Said Twilight.
"Well, when Night Light and I broke up, we don't know, but I was pregnant with your half-sister Twilight. When the baby was born, your parents were already married and your mother was pregnant with Shining Armor and I choose don't tell Night Light about our child, which could be dangerous to him and your family, and until today he does not know. I take care of the little filly for some months before leaving her on the Canterlot Orphanage, where I could visit her every time I wish without attracting suspicion. A few years after, I took that little girl as one of my most loved students. This girl is you Sunset, you're my daughter."
The room stays in silence for a few seconds.
"I'm... your daughter?" Asked Sunset confused
"She's my sister?" Asked Twilight with surprise and confusion in her voice.
"I'm your daughter?" Spoke Sunset, her voice was a mix of anger and sadness and so she raised her voice.
"Why didn't you told me this years ago? Do you have any idea of how much pain I felt? How many times did I stay alone up the night, crying until sleep? Did you how long I've waited to know who my parents could be? How many times did I look at the ceiling trying to understand why my parents abandoned me?" she shouted with tears filling her eyes she shouted with tears filling her eyes
Sunset's horn began to glow, sparks flying while she walks side to side, staring at Celestia.
"Did they don't love me? I wasn't planed? Did they want a colt and not a filly?" Sunset's voice was full of confusion and sadness.
"All ponies there were adopted, except me. All the other ponies founds a family but not me. All my childhood I was alone, suffering until I've decided that if my parents don't want me, I didn't need them too" Sunset's anger was clear in her voice.
"The only thing that makes me happy in that place was your visits princess, showing that you cared about us, that you cared about me." Sunset's voice was a mix of anger and sadness
"When I entered your School of Gifted Unicorns, I saw you like the mother that I never had, and for the first time in my life, I think that I could be happy, but you continuously denied to explain what I saw in the mirror, what is my destiny. You kicked me out of your life, I've lost the company of the only pony I ever thought that loved me that and I truly loved. I loved you and you abandoned me, I run to the other side of the mirror and you did not even care if I was fine if I was alive"
Celestia remains in silence while Twilight just watches motionless. With tears in her eyes, Sunset continues to speak.
"I was alone for years and years in a strange world, without family, without friends, without nopony to support me. When the portal opened again, I stole Twilight's crown, and I would use it to take over Equestria, to show you that I wasn't anymore the pony who admired you, who wanted to be like you! I would show you that I was stronger than before, that you don't have any domain over me. That if you don't give me my place at your side, I would take yours."
"Twilight and the others defeated me, and even after all the bad things I did, they forgive me, accepted me, be friends with me, and helped me be a better person. Twilight, Applejack, Fluttershy, Rainbow Dash, Rarity, and Pinkie Pie, became my family, something I always dreamed of but never had when I was here in Equestria. They received me in their homes, their families. After so much suffering I finally found my place, my peace and now you tell me that is all your fault? You know everything and did nothing, you let me think that nopony loved me, that I was alone in the world. I came here to beg your pardon for all my mistakes, to try to be friends again with you, but I don't know if I want this anymore."
Sunset sits with her back turned to Celestia. Twilight placed a hoof on the fiery unicorn's shoulder.
"I never imagined that you had passed for all this Sunset. But after all of you lived, you become a better person, a better pony, can't you forgive her? We all make mistakes, but we need to be able to forget..."
Sunset quickly stands up and turns to her friend.
"She lied to me Twilight!!! all my life was a big lie!!! I never was anything more than a big joke to your beloved princess, how do you expect that I could forgive her for this?" Sunset shouted with sparkles flying from her horn, which made Twilight shrink and take two steps back.
"If I am a better person today is because you showed me there's another way, that my past could be left behind, that I could exist beyond my errors, but all that happened to me was her fault!"
"She knew that we were sisters and send you to stop me without telling that. All could be different if I at least know there was somepony in the world who cares about me, I didn't would turn into a demon full of hate and thirst for power, I would never try to kill you, or even meet my friends and hurt them. I could be happy Twilight and she, your beloved princess denied me this."
"Sunset, the princess..." Twilight is unsure if she can say anything to defend Celestia, but fortunately, she doesn't need to, the princess place a hoof on her shoulder and began to talk
"She's right." Celestia leaves Twilight and sits on Sunset's side.
"Sunset, I know that after all what I did to you I don't deserve pardon, I will never forgive myself for all the pain I caused to you. All this time we were apart I missed you so much, abandoning you was my biggest mistake, you don't have any guilty and I make you pay for my errors."
Celestia walks and sits in front of Sunset, looking at the unicorn in her eyes she takes off her crown.
"I'm here not as Celestia, the ruler of Equestria, but as a mare deeply sorry for her acts, begging you pardon, even knowing that I don't deserve it. Please give me a chance to restart and finally be your mother and stay at your side. Let me be part of your life even if not as your mother, but if in your heart you can't forgive me, I'll understand, and will not more interfere in your life."
Sunset stays silent for a few seconds before talking to Celestia again.
"Princess, I need to think very well in all this before I can talk to you again. Now I'm really upset with you and don't want to say anything that I could be sorry about later. Goodbye, princess."
Sunset stands up and slowly walks lower headed through the path until the throne room doors, and teleports herself out of the castle. The princess remains on the floor, watching her daughter disappear, Twilight walks and touches her back.
"You will be fine, princess?" Asked Twilight.
Celestia closes her eyes and takes a deep breath before answering.
"Immortality is a huge burden Twilight, the kind of I don't wish to no pony. They say that with the years the wisdom comes, that you grow up and learn from your mistakes, but look at me, alive for more than a millennium and even so, I make the same mistakes. I banished my sister to the moon, and in my fear, my cowardliness, abandoned my daughter, a defenseless little filly for who I was her world, all the bad choices he made, all that happened to her was my fault, I destroyed her life, Twilight. I was a fool thinking that she could forgive me" Said Celestia with a deep sadness in her voice.
"Princess, I know Sunset, I may not know how was your relationship before, but one thing that I know is that today she's a better pony, a deeply changed pony, not more that young mare who run away from you years ago. She learned the value of friendship and how important is to forgive those who fail because she already was in that place. I'm sure she will forgive you one day, just give her some space and a little time to process all this" Said Twilight cleaning the tears off her former teacher's face.
"When you became so much wiser than me, Twilight Sparkle?" Spoke the princess with a little smile on her lips.
"What can I say, I had a great teacher. Princess you and Sunset are my friends and if I know both of you, you will be fine soon, I'm pretty sure. Now, I have to find Sunset and see if she's fine, you will be ok?" Asked the young alicorn.
"I'll be fine Twilight, don't worry. Now go find your friend, she needs you" Said the Sun princess.