Author's Note
Here it is, a one-shot Mother's Day story. 
I'M SO SORRY AJ.
You're my mom?!
"I just don't think it's a good idea to come back there." Sunset Shimmer said to Twilight Sparkle. "Everypony remembers how I was before I was banished to the human world, Twilight! You know that."
Twilight hesitated to answer. "Yes, I do know that. But I just think if you redeem yourself you can finally live the life you want!"
Sunset sighed. "Twilight. I've already done enough to both our world and this one. Nothing can be done. No one will ever forgive me. Even the people here haven't forgiven me since we saved their lives at the battle of the bands."
Twilight sighed as well. "True. But I just think if you give it a shot, good will come out of it! Even Princess Celestia wants you to come back."
Sunset Shimmer was taking a drink of water then spit it out. "PRINCESS CELESTIA WANTS ME BACK?!"
Twilight was confused. "Yes, I thought you knew that. She's the reason I came back here to try and get you to come back to our world."
"Of course I'll come back then!" Sunset said, relieved.
"Then it's settled?"
"Yep. I'm coming back to the pony world!"
_______________________________________________________________________________
Sunset and Twilight walked back through the portal into the pony world.
"Girls, I would love for you to meet my dear friend, Sunset Shimmer!" Twilight announced.
Sunset's mane was in her face and she slowly pushed it away. "Hi..."
Apple Jack, Fluttershy, Rarity, Pinkie Pie, Rainbow Dash, Princess Celestia, and Princess Luna were all standing in front of Sunset.
Apple Jack took her hat off. "Howdy there Sunset, I'm Apple Jack. You can call me AJ if you'd like."
Sunset brightened up a little to see that the girls were being nice to her.
Pinkie Pie hopped over to Sunset. "Hiya there Sunny! I'm Pinkie Pie!"
After a while all the mares had introduced themselves to Sunset. Sunset felt better knowing that the ponies that were once her enemies are now her friends.
Sunset's brightness went away as Princess Celestia trotted towards her.
"H-Hi p-princess.." Sunset stuttered.
"Hello, Sunset. It's nice to see you again." Celestia replied. "How have you been these past years?"
Sunset brightened up even more again to see that her old teacher who she had tried to over-throw wanted to meet her.
Sunset swiftly replied, "Very good! How have you been Princess Celestia?"
Celestia hesitated to answer. "Very good as well Sunset."
It had hurt Princess Celestia ever since Sunset Shimmer was banished to the human world. Her only daughter, wanted more power, so she had to get rid of her. It still haunted her to this day. Having to erase her daughter's memory to think that they weren't even related. Only to find out she posses the same magic she was intended to, without her help. Celestia was hesitant with inviting Sunset back, knowing she was able to save both their worlds without her help. But she finally stirred up the courage to do it. It hurt so much hearing her call her 'Princess Celestia' and not mom, or mommy, or momma. That was the reason Princess Celestia invited Sunset Shimmer back to the pony world to visit. But now, since Sunset Shimmer was here and had been introduced to everypony, including Princess Luna, Princess Celestia had to figure out a way to say, "You're my daughter". But finally after a long time of thinking she decided that she had to say it, and that no matter how she said it, or what tone she said it in, her long lost daughter would love it.
"Sunset. I need to tell you something very important." Princess Celestia said, hiding her tears. "In private, please."
Then, one by one, the other ponies trotted out of the room.
Sunset hesitated to ask. "What is it, Princess?"
Celestia couldn't hold it in anymore. Years of lies, betrayal, first her sister, then her daughter. She couldn't keep it in. Then she said it. "Sunset. You're. My. Daughter."
Sunset didn't know what to think, all these years she thought it was just her mentor. "But I thought you were my mentor? H-How are you my mother?!"
Princess Celestia couldn't hold back her tears anymore either, she started sobbing right then and there. "Well, you wanted more power in Equestria then tried to over-throw me. I had no choice. It was Luna all over again."
Sunset started to cry as well. "I know about the over-throwing wanting power thing but how am I your daughter?!"
Celestia could barely see Sunset through her tears but continued talking. "Well, I had to erase your memory so you would think you were my student."
Sunset was confused. "What about everypony else? They would have noticed if 'Princess Celestia's Daughter' just went missing."
"I had to erase their memories to. Only the memory of you as my daughter though, everything else they remembered." Celestia replied.
Sunset started to put two and two together. She just couldn't believe it! Princess Celestia, ruler of all Equestria her mother! How could this be?! It just feels so unreal!
Sunset was as excited as ever and began to think, Princess Celestia's royal daughter. "Wait...Was I an alicorn too?!"
Celestia stopped wiping her tears and stood frozen for a second. "Well, yes. You were an alicorn, but I sort of did the opposite of the alicorn transformation on you. Just so you wouldn't have any alicorn magic anymore. But, I will turn you back. W-Well if that's okay with you. Being an alicorn princess. I don't know after all you've been through in your life."
"Sure, I guess. I mean it would be nice to have more friends, after the an incident that happened in the human world. Nobody wanted anything to do with me after that. I only had five friends and that was basically it for me." Sunset replied.
Celestia started weeping a little bit again. "Who were those friends?"
"Well, how do I put this correctly? The human versions of Apple Jack, Rainbow Dash, Pinkie Pie, Fluttershy, and Rarity." Sunset answered.
Celestia started laughing. "Wow. Sounds like quiet the group of friends you have there."
"Yep. We're always into something." said Sunset laughing as well. "I love you, mom."
Celestia was shocked, she couldn't have waited any longer to hear those words. "I love you too, Sunset."
Author's Note
Hi! Hope you like the extra ending chapter!~Lightning
Extra Ending
Pinkie turned her head back near her friends, as excited as ever. She kept on squirming with excitement.
"Pinkie! Would you stop squirming?!" Rarity yelled. Pinkie continued to squirm, follow be fast-paced breathing. Twilight was very annoyed at this point, but she was worried about Pinkie.
"Pinkie, stop hyperventilating! You could pass out! Just calm down!" She said, trying to reach her hoof over to Pinkie.
Twilight accidentally touched Rainbow's wing, and she cringed. "Yuck Twilight. Get your hooves off me!" Twilight was at wits end after being with her friends being cranky.
"I'm sorry Rainbow! I'm tired of being in here with all of you since Princess Celestia and Sunset wanted some 'alone time' Pinkie locked us in the closet!"
"Oh yeah.....Continue..." Rainbow sighed. Fluttershy had not said a single word at this point in time, but she was VERY angry.
"'Oh yeah continue....' Dur dur dur..." Fluttershy murmured.
Rainbow heard, and was very surprised about Fluttershy's remark. "What was that Fluttershy?"
"Nothing...." Fluttershy said, as she was hiding.
"Pinkie, in Celestia's name was it necessary to lock us in a closet?" Apple Jack said, trying to move away from the problematic area of the closet.
Pinkie face-hoofed so hard she made herself dizzy, but everypony helped her up on her hooves. "Okay, I admit, it wasn't that necessary to lock us in here, but I needed a space to spy on them."
"Why do you always have to spy on everypony?" Rainbow said, annoyed.
"Well I-" Pinkie said as being interrupted by what was going on between Celestia and Sunset. "Oooh! They're hugging and crying! Now they're coming this way!"
"I can't wait to see what they have to say." All mares said in unison.
