Sunburst leaving Starlight Glimmer without even saying goodbye after getting his cutie-mark wasn't the only thing that caused her to start the village without cutie-marks, identities, personalities and dreams. Starlight's childhood was filled with more than one friendship dying to cutie-marks.
Find out about Starlight's childhood, and how she lost many friends to cutie-marks, how a friend turned into a bully because of cutie-marks, how destiny (cutie-marks) have complete power over ponies (to Starlight's dismay), and read to see Starlight become more bitter on the way there!