Angel Heart  
okay, trying not to make her too cliche. yay peasants.  
Angel is an earth pony born in Canterlot, to a pair of housekeepers. She grew up as a maid in the kitchen, earning herself a cupcake cutie mark. She cleaned, cooked, and took care of unicorn foals of the posh unicorns her family worked for. When she learned to read, she grew a passion for fairy tales, and longed for her own fairy tale to finally happen. Deciding that she should leave Canterlot to follow her dream, she tried several times to end her servitude with her owners, quite difficult as her family had been in service for generations. They eventually let her go, warning her that she would never find a good job again. Angel ignored them, intent on traveling to Applewood to either try for stardom or find a wealthy stallion.  
But she never did leave Canterlot.  
No longer a house slave, she needed to find some means to ever afford the trip. She tried to get work around town, but because of her lack of experience and education, she was turned away, over and over again. Disappointed, she tried to get back into some sort of cleaning service, but because of her naive and ignorant ways, no one wanted to put up with her or her clumsiness. Desperate, but too proud to run back to her family to beg their owners to take her back, she turned to the shady corners of Canterlot, where mischief ran rampant in the shadows. Her exposure to this side of Canterlot taught her that life is no fairy tale, and that every coin has another side.  
Recently, this young mare has been lurking around the streets of Canterlot, waiting for a chance to have a fresh start, though where she will go now remains a mystery. Her past remains very shady, and she often tells a different story each time, as if to hide something.