There was a war that lasted a couple of years when she was a filly, her parents talents were magic, so they were soldiers. When the enemy attacked her village, her parents were there to help get her onto a cart that led the young ones to safety. She wouldn't see them again, the last thing she remembers is seeing her mum and dad put up a magic barrier to shield them from magic blasts and seeing cracks forming in it before losing all memory of anything that happened then and about an hour afterwards.
A year later, she discovered she was exceptionally well talented at magic, but unlike other ponies who study and learn magic, her talents were natural. She could cast spells without having to study anything at all, or learn the mathematics or any parts of how the spells function. One day on a field trip with the classmates from her orphanage, a large bear had been seen charging them from out of the woods. It was too early for bears to be waking up, so it probably woke early and was very hungry. In a panic she had stepped forward in the front of the line they were all standing in and instinctively projected a reflection barrier that bounced the bear backwards by using the bears own running force when it collided with her shield, sending it flying away. After receiving much praise from the other orphans in her class and the head of the school that was with them at the time, she off handedly remarked that she remembered hearing that her own parents were defensive magic specialists. On realizing that her parents that she lost a while ago were also specialists in defensive magic, she knew exactly what she wanted to do. To practice magic, defensive magical spells so that she could protect other ponies like what she just did then, and what her parents did for her, but unlike her parents, she was driven, driven to master barrier spells so strong that "NOTHING" will ever break them, that her protection will never break, never falter, and never give way to any force no matter how strong or persistent. She wanted to be the worlds greatest shield master...oh...and flowers....she really loves those too!..and then poof! A 5 pronged star shaped flower appeared on her butt.