Siblings VS. Changelings

On the day Anonymous turned four, something strange happened at the Changeling's hive. One of the Changelings had stumbled across a strange orb that temped it to pick it up; when it did pick it up, it got corrupted and turned into an Alicorn Bat Pony with Changeling capabilities.

The Bat Pony fought the Queen Chrysalis who had a baby Princess Daughter. "Run while you still can, my child! Run!" she shouted to the Young Princess, "You better run," said the Bat Pony, Chrysalis then said: "Transform into a unicorn and run!"

She had no other choice but to obey her mother, she ran and transformed into a light blue Unicorn with yellow hair. She then fell  directly into an apple farm and hit her head so hard that she forgot everything, the Changelings, her mother, the Bat Pony, she even forgot how to transform, so she lived her life as a Unicorn; this young Changeling was Starling Heaven.

At school, she never knew why, but she always got some kind of strange feeling whenever studying about the Changelings. Nevertheless, Starling idolized her older brother, Anonymous. When She and her adoptive mother went to Anonymous' graduation however, things changed for Starling.

"He's not really your brother, Starling."

"Huh? What do you mean?"

"When he was four, he found you in the forest near the farm; you were only a little foal when it happened."

"So I'm... not your real daughter?"

"Well, your still part of the family, just not biologically."

Anonymous never knew that Starling was even told that she was adopted.

When Starling was eventually sent to Ponyville for Magic School, that's when she started to shine! You see, she was sent to my castle, and I accepted her as my pupil.