Emerald Sea

Emerald Sea was raised by an abusive "mother" who took her in when she was a baby. She was born an alicorn, during the time right before Nightmare Moon was banished. Because Luna's betrayal was still fresh in equestria's mind, any alicorn that wasn't Celestia was seen as a threat. The pony who raised Emerald Sea and her adopted sister, Lightning Star, because an outcast. While she loved and cared for Lighting, their mother hated Emerald Sea. Lightning Star got to go to school and was super popular, while Emerald Sea had to stay home cleaning the house every day. Because of that, she was bullied for being a blank flank. Lightning would defend her sister, but it didn't stop the ponies from harassing her when she was out alone. 

One day her "mother" was abusing her and Lightning Star walked in on it, and was stunned because Emerald was told that if she told her sister she'd be hurt even more. Lightning galloped out of the house full speed to find anyone she could tell, and eventually accidentally bumped into Celestia, who was outside staring at the moon, missing Luna. When the princess asked why the young pony looked so upset, Lightning Star told her everything, and Celestia sent her guards to arrest their "mother" and bring the young pony to the palace. When the guards got there, the "mother" was gone, but they brought Emerald Sea back to the palace, where Celestia gave her a room and began teaching her magic.

Has very low self-esteem, but is learning how to love herself and be happy.

She tries to be polite to everyone, and even 4 years after leaving her "mother" she still flinches when anyone raises their voice or touches her.