Sunset Shimmer (Equestria Girls)

Overview
Sunset Shimmer was a unicorn who lived in Canterlot and attended Princess Celestia's School for Gifted Unicorns. A series of misdeeds resulted in her being banished to the human world. She became a student at Canterlot High School, where she made plans to take over Equestria.

Early Life
Sunset Shimmer lived in Canterlot, in the land of Equestria, and studied magic under the tutelage of Princess Celestia. The princess remarked that Sunset was one of her prize pupils. Over time, Sunset craved more power, eventually letting it corrupt her to a point of trying to usurp Princess Celestia's power. This resulted in her being banished from Equestria, and sent through the mirror portal into the human world.

Living as a human
Sunset adapted quickly to life as a human, using the time to plot her eventual triumphant return as Equestria's leader. She lived as a student in Canterlot High School, and soon became the terror of the school bullying the other students into doing her bidding. She attempted to bully Raven Sable, culminating in Sunset insulting Raven's mother to a degree that a full-fledged fight broke out between the two. Brought before Principal Celestia, she was cautioned that any more behavior of that sort would result in her being expelled from CHS. Following this, she kept a lower profile, avoiding Raven as much as possible, and continuing her plans for the domination of Equestria.

Rampage
Seizing the opportunity when the portal opened after 30-moons, Sunset was able to steal Princess Twilight Sparkle's crown and return it to the human world. Her plan was to have herself crowned the princess of the Fall Formal, which would unlock the magic contained within the crown and allow her to march an army of slaves through the portal and seize power in Equestria.

Her plan was thwarted by Princess Twilight, who had come through the portal to retrieve her crown, and the assistance of Gemini Shadow and Raven. With Gem's and Raven's help, along with the assistance of other students at the school, Princess Twilight was crowned the Princess of the Fall Formal. Sunset, furious that her plan was about to be derailed, threatened to destroy the portal and trap Princess Twilight with her in the human world forever. Twilight defied Sunset, and in the process of passing the crown around to keep it from Sunset's clutches, it eventually fell into her hands. She underwent a transformation into a she-demon. Using her power, she quickly placed the student body under mass hypnosis and began the march on Equestria. However, Twilight, Gem, and Raven joined forces and, using the Spirits of Harmony found in the human world, were able to stop Sunset and return her to human form.

Sunset was apologetic following the loss of her power, and explained she saw no other way to gain the power she craved. At Princess Twilight's suggestion, she attempts to make friends with Gem and Raven. The crown was returned to Princess Twilight, who returns to Equestria, leaving Sunset to start over.

Redemption
Over a period of about a week or so, the redemption process begins. With Longhaul's assistance, Sunset cleans up after the wreckage she made the previous night and then serves a week's suspension, during which time she grows closer to Gem and Raven. At Christmas, a distraught Sunset is invited to Raven's house for the holiday, and she shares a tender moment with Gem on Christmas Eve night. After her return to school, Sunset began the long process of trying to restore her name with the other students of CHS.