The wind and rain outside left a chill in the entryway of Twilight's castle. A mare stood at the door, soaking and pitiful. Her head hung and her legs shook, an obviously exhausted figure. Twilight instinctively shuffled the mare inside and embraced her in her magnificent wings. "You're freezing cold. Sleeping Spell, go fetch me a blanket."
The little colt cantered down the hallway to complete the task. Twilight Sparkle tenderly rested her chin on the mare, who's body began to heave with sobs. She closed her eyes and shushed the mare gently. "Oh, Starlight… Shh, I'm here. What is it, hm?"
Starlight Glimmer began to sink to the ground in exhaustion. In her arms was a foal, pale and thin, silent and obviously struggling. Starlight gazed up at Twilight with tear-filled eyes. "She's here… I-I'm sorry…Twi-Twilight I'm sorry." She nudged the foal desperately. "I can't g-get her to cry anym-more…"
The feathers on Twilight's body stood on end. She acted quickly and grabbed the foal in her magic. "She's so early!" Twilight's voice was laced with genuine concern. "She's so small…"
Sleeping Spell had returned, levitating the blanket his mother had requested. Twilight Sparkle snatched it from him and hastily wrapped the foal and held it to her chest. She rubbed the foal with her hooves, trying anything to stimulate the child enough to cry. It squealed indignantly and began to wail softly. Starlight pushed herself to her feet and gazed at her premature daughter.
"I'm sorry…I-I know you were e-expecting her later…I…I d-don't…I don't know what happened." The words stumbled from Starlight's tongue in a desperate mess. "I d-don't know what---"
"Starlight, you don't need to be sorry." Twilight interrupted her gently. "It's alright, you couldn't help it."
"Mama," Sleeping Spell spoke up. "Is this my baby sister you told me about?"
Twilight's heart melted at his innocence, oblivious to the panicking mother and sickly state of the child. She moved to answer his question.
"Yes," Starlight answered instead, sniffling. "This is your sister. Her name is Silver Ribbon."
She offered a weak smile and gave Twilight a nod. "When will you tell Sunburst?"
Twilight hesitated and looked down at the foal once more. She frowned. "Not now."
Starlight understood. She took a few shaky steps forward and nuzzled the foal she had given life to. She felt a pang of sadness for the fact that she wouldn't raise the child herself.
"Go home to Trixie." Twilight murmured kindly. "Silver Ribbon is home now, we'll take care of her."
I guess this isn't too terrible of a way to introduce another one of my NextGens, Silver Ribbon.
Silver Ribbon is the biological daughter of Starlight Glimmer and Prince Blueblood, the accidental product of a one night stand at a Grand Galloping Gala. Shortly after the encounter, Starlight Glimmer entered a committed relationship with Trixie Lulamoon. When Starlight found out she was pregnant, she panicked and approached Twilight for help. Twilight immediately offered to adopt the child. Starlight agreed, and Twilight cast a spell to disguise Starlight's pregnancy. Twilight took on a spell that made her appear pregnant and told Sunburst that she was expecting.
In this particular scene, Sunburst is luckily on a trip to the Crystal Empire, so Twilight just plays the premature birth off as her own.
Silver Ribbon grows up as a princess, genuinely believing she is the daughter of Twilight Sparkle and Sunburst.