Sparkling was born to two unicorns, and was a happy if shy filly. She grew up in Canterlot, and looked up to Queen Solar Flare in an almost fanatical adoration. She wished she could be strong, and tried her best to learn about magic. She studied and studied, and grew to be quite the scholar. She acquired access to many important texts and scripts, and grew very powerful in her magic as she had hoped. During the war, she tried to use her magic in an effort to help ponies, both refugees and soldiers. What ended up happening was that she was captured when the Changelings raided their camp near the south edge of Everfree Forest.
 
It was months before she was ever found, locked in a cellar deep in the caves of the Everfree, repeating gibberish over and over again, using her horn to copy and write every spell she had ever laid eyes on. They never knew what happened to drive her over the edge into insanity, but they knew it completely decimated her. There was little they could do for the filly. It was even crueler when they found she gained her cutie mark while she was in there.
 
A few weeks after, Sparkling was held before the Queen for what had happened. The Queen decreed that Sparkling had produced powerful spells to the enemy and had betrayed Equestria. But, she was much more kind that most realized, and decided it was unfit to execute the unicorn whilst she was insane, and allowed that as long as the unicorn was not of stable mind, she would not be executed.
 
This was a bittersweet sort of relief, but the Queen did have a point. Sparkling did not seem able to snap out of her trance that she had fallen into (dubbed “deponifization disorder”.) and hardly seemed aware of herself. She could function at the bare minimum, eating, sleeping, bathing. But she was not as she was before. She did not read or cast spells, or otherwise. She was very cooperative, although if she was startled or frightened she could cause havoc.
 
In recent Equestrian News, there was a riot in the hospital where Sparkling had been kept. It took days for it to be put back under control, with massive casualties and many patients missing. Sparkling was unaccounted for, although there was no alarm raised. The doctors simply thought she must have drowned in the nearby lake, and did not wish to endure the wrath of the Queen.
 
Sparkling found her way through Equestria, almost half-sane enough to function a bit more than normal. She can now form small sentences and walk around during the day, but she prefers to travel during night. She still cannot and refuses to use her magic, and has now taken up a small job as a librarian in Ponyville, and has now changed her name to “Twilight”.