Once upon a time, doesnt always have a happy ending and for one young Princess the ending is just as bad as her beginning.
When this Princess was a young filly her and her sister were given a destiney. No one understood it at the time but when the sisters grew up they understood it all.
The begining starts off with two young fillys one of the day and one of the night. The older was of the day and while she basked in the glory of the sun and the praise the ponies of the land the younger hid away in the shadow of her sister. The younger grew upset and became angry and with that hidden rage her magic grew into a hideous form that would soon overtake her and consume her.
But before her rage she took comfort in another filly who was feeling misunderstood. She too was a Princess and like the moon Princess she was hidden in her sisters shadow. The moon Princess and the shadow princess became fast friends because of this.
When the time came for the rage the moon Princess hid her friend could not stop it. The fight between the two celestial sisters was scary as the shadow Princess watched from her hidden spot. As the Sun Princess used the Elements of Harmony against the Moon Princess, the Shadow Princess's sister entered the damaged castle and called out for her sister. The Shadow Princess ran to her sister in tears. The older Princess comforted her sister but then there was a shatter and both Princess's looked to the sky where the moon shone full and bright and where it was blank and pure now held the figure of what the ponies of today called the Mare in the Moon.
Two nights passed and the Shadow Princess couldn't take it any longer. She grew uncontrolable with rage the same rage that the Moon Princess had felt when her sister had blocked her from sharing the praise. She marched to the Sun Princess's hall and burst through the doors in her rage and as she did her magic and hatrid grew as well. Shocked the Sun Princess stood defensless as the Shadow Princess stalked into the room.
"All she wanted was to feel important to you! You made her this way, you turned her into Nightmare Moon, and now you're going to pay!"
From the hallway came the Shadow Princess's sister, "StarGlimmer!" The Shadow Princess turned and for a moment the rage had dissapeared. Then she blinked and held her ground staring down the Sun Princess. "You ruined her! Why couldnt you just let her shine with you??" She took an angry step forward but before she could take another her sister was there in front of her.
"StarGlimmer please this is NOT you." StarGlimmer stopped and looked at her sister, "Sunspot, Please step down, I have to avenge Luna.." StarGlimmer touched her sisters side gently with her wing and pushed aside her. Walking closer to the Sun Princess but again her sister was in front of her. "StarGlimmer I will not let you hurt Celestia." Sunspot spoke bravely, and though her sisters magic was brewing and throbing with rage Sunspot did not step down and she blocked Celestia. Taking a step back StarGlimmer looked from her to Celestia. Then Suddenly she lost it and the two sisters fought. As Celestia watched in horror the two sisters fought in the already ruined castle. Hours went by and just when StarGlimmer grew tired her sisters horn began to glow and with tears in her eyes SunSpot defeated her sister.
After the second battle there wasn't only a Mare in the Moon but a Mare in the Stars as well and on nights when the moon was full and the Mare in the Moon radiated the Mare in the Stars glimmered and spoke the story of how they came to be.
Two Princess's lost in their dreams became lost in the Night sky.
Many seasons passed until the Mare in the Moon began to fade. And stories of old began to come true. When the Mare in the stars horn began to align the Mare in the Moon would be revealed. Celestia and SunSpot knew that not too long after Nightmare Moon returned that StarGlimmer would as well. But they had a plan for that and when it came time a new star would rise among the Alicorns.
A young filly began her training as Princess Celestia's new student to defeat not only Nightmare Moon but also StarGlimmer.
Again more seasons passed and that young filly grew to be Celestia's strongest student besides SunSpot. Celestia was proud of her student and because of that she almost told her the full story of Luna and StarGlimmer. But Celestia couldn't bring herself to tell her student. Sunspot had moved away from the old castle and somewhere she could watch the skies for the time when her sisters stars align and when they would she would send a warning to Celestia.
When the stars had aligned and Luna- Nightmare Moon- was realesed from the moon, Celestia's student was strong enough to change her back. And when Luna had returned to her normal self she searched around for her old friend and when Celestia had come clean Luna was upset and angry but she never returned to being Nightmare Moon. After she brought up the moon she searched through her sisters dreams and through SunSpots nightmares, she watched and re-watched those images as SunSpot transformed StarGlimmer into the Mare of the Stars.
Luna watched the stars more than SunSpot did. She waited and watched even as Celestia's student became an Alicorn and she had her own castle right there in ponyvile.
It was the fall after Princess Candence took her place in the Crystal Kingdom, it was the winter when Celestia's student saw something change in the stars. It was the spring when the stars really began to shift and Twilight Sparkle brought it to attention to Celestia and Luna.
It was a normal spring day when Twilight Sparkle noticed that there had been a major shift in the stars. But Luna had already known this. And she patiently waited until it was her time to raise the moon.
Meanwhile Twilight and her friends raced to the castle to warn them that something bad was about to happen. As Celestia lowered the Sun and Luna stood proud with tears in her eyes she started ro raise the moon. And when it was half up the stars began to glimmer and as Twilight and her freinds ran up the hill SunSpot shimmered in and stood between the two Princess that started it all. When Twilight and her friends got to the hill, Luna had raised the moon to its full height and suddenly there was a bright blue flash. Ponies all across Equestria looked to the night sky and were shocked at the blue light that emerged from the stars. But not quite as shocked as Twilight and her friends when they saw the small curled shape laying in front of them.
StarGlimmer blinked her eyes and sat up over looking ponyvile. She looked behind her to the ponies standing behind her. She scanned the ponies across the hill her eyes stopped on SunSpot her eyes clouded and she stood uneasily. StarGlimmer walked uneasily to her sister and bowed her head.
"Sister I am sorry.." Tears formed as StarGlimmer apologized to her sister. With her eyes full of tears she walked over to Princess Celestia and bowed her head low and her tears began to stream down. "Im sorry I was so horrible to you after luna was away in the moon. I was so obsessed with Luna and taking up her rage and keeping it from her.." She stopped as a familiar smell filled the air around her. She turned suddenly and Luna was there beside her. "Oh Luna! I took all your rage and bundled it all up inside of me and when Celestia sent you into the moon I lost it, I took it all up and turned it against your sister just like you always wanted." Luna rested her head down on StarGlimmers head and whispered "No dearest StarGlimmer, I wanted the ponies to enjoy my moon and praise it. I took all my anger and Nightmare Moon consumed it. I never wanted to hurt Celestia, but I did. She lost a sister."
Sunspot walked over to her sister and gently tilted StarGlimmers head up, "Sister you are here now, and thats all I care about." Celestia had been quiet for a while and when she poke StarGlimmer ducked her head. "StarGlimmer," Noticing the young pony's head she spoke calmer "Join us, you are home now and we all be honoured to have you rule with us." StarGlimmers head popped up. "You mean I get to rule with you?" Celestia nodded and backed away to talk to TwilightSparkle.
StarGlimmer looked from her sister to Luna and smiled "I'm home!" Luna smiled back as did SunSpot
"And I have the perfect job for you." Luna whispered in StarGlimmers ear. "You can help me... You are in charge of raising the stars." StarGlimmer from that night onward coaxed the stars from the sky at night as Luna called to the moon. The two watched over all of the ponies dreams. Luna checked on her friends dreams while she was asleep and there was now peace between StarGlimmer and Celestia.
As Celestia explained to her student Twilight and her friends, she told them that she had been afraid that StarGlimmer would have come back ready for revenge but now that she turned away from her student to the pony smiling happily at the stars she knew that StarGlimmer would be alright. Ponies alll across Equestria came to watch the newest of the Alicorns raise the stars. They called out her name and she earned a new name that night as well. For she was no longer the Shadow Princess but she was now the Star Princess. Everynight she looked to the stars that contained her once upon a time. As she watched her best friend raise the moon she caught the tip of the horn glimmering brightly.