So, If you don't know the history of Fallout Equestria, the Grand Pegasus Enclave is essentially a giant military force that keeps the population of Pegasus above the wasteland in the clouds. Since the first bomb dropped, and destroyed Cloudsdale completely, the Pegasi closed off the skies, creating a thick layer of cloud cover that blocks out the sun. Rainbow Dash did not approve of this, and tried convincing all the Pegasi to leave, and help the wastes. No pony listened. Rainbow left by herself, and the Enclave made an example of her. Anypony that speaks out against the Enclave now, 200 years after the bombs, is branded with Rainbow Dash's cutie mark. This process destroys the ponies cutie mark, and replaces it with the burned outline of a cloud with a lightning bolt. The pegasus is then thrown from the skies, and forced to live in the wastes, where all the unicorns and earth ponies hate pegasi for leaving them all those years ago, and still hate them now. You're welcome, yes it's sad.