Rainbow Dash was your normal filly with billionaires for parents. She loved them and they loved her. Everyone was happy until the one fateful night coming home from the movies. That night, Rainbow saw her parents be murdered in front of her own eyes. When their killer is released from prison on good behavior, she takes upon the persona of a superhero named Batmare. She vows to her parents vengeance upon their murderer and all of the criminal scum in Ponyville.

It looks like tons of people have already come up with this idea, but none have done it with Rainbow Dash, right?