Cutie mark: Parhelion
Class: Celestial Paladin
Family: Parents and her older sister, Moonbow
Romantic interest: Nopony yet.
I have a roughly-"sketched" flashback of her backstory:
Her parents were glass blowers, and their shop was in their house.
One day, when Parhelia was just a filly, just after the shop was closed up for the evening, her mother left to get icecream. She told Parhelia to wait for Moonbow and her father so she could tell them where Mother went when they got home. Parhelia figured it would be funny to hide in the kitchen closet and ambush her family when they got home. But through missing louvers in the door, she could see that somepony--a unicorn--stopped them before they entered their home, and took them both out with whacks to their heads with a metal pipe. Parhelia jumped out of the closet, but the unicorn spotted her and held the entry door shut with magic before she could even get to it. There was another pony, too, but its appearance startled Parhelia; she'd never seen a changeling before, or even knew of their existence. Together, the changeling and the unicorn quickly dragged the bodies into potato sacks, and from there, she couldn't see where they had been moved. The door was still locked, somehow, and she was unable to leave her house to follow the attackers. A town guard that was patrolling the area finally came around a corner, suspicious of noises he may have heard just now, and Parhelia was able to get his attention. But not a moment later, she saw her father and Moonbow come back into view, perfectly fine, except they were arguing, and Moonbow took a defensive stance. The guard tried to break up fight before it started...But Parhelia's father dove at Moonbow, and the mess started. Young Parhelia was useless, struggling to get the door open and screaming to get everypony's attention so they may stop. There was dirt-throwing, brick-smashing, and the guard was trying his best, but wasn't able to stop ANY of it. Eventually, the pony's father took her up into the air and slammed her down, permanently pacifying her.
Her mother came around the corner to find the bloody mess that was once her beloved family. Her husband fled
The only witnesses were Parhelia, her parents, and the town guard.
Her father was found shortly after the incident, and imprisoned for the murder of his own daughter. But he didn't remember any of it. It was only over time that he began to believe he actually murdered Moonbow.
Parhelia didn't, though. For the rest of her life, she grew up and knew he had been framed.
When the Changelings invaded Canterlot, that's when it clicked. That's when she realized her sister may still be alive someplace, and she had developed a vein of pure hate for the changelings. From that point, she devoted her life to bringing justice to her father, her sister, and anypony who is a victim of deception. She worked hard and earned Celestia's blessings.
She is going to find her sister.