“Tirek’s gambit for Equestria was ultimately a failure, but before he was locked in Tartarus he managed to take a few ponies with him. Over time, the evil land corrupted the Equestrians into demonkin, Rarity being one of the newly-branded ones. Somehow she managed to sneak past Cerberus and the ageless guards at the gates and escaped the dreadful place.
 
“She thought Equestria was gorgeous and wonderful, but the feeling was not mutual. Fortunately Rarity quickly met a young Fluttershy, who taught her changeling magic so she could look like normal ponies. She has since learned the art of dressmaking and the joy of generosity, and she’s not very inclined to go back to Tartarus ever again.”
 
Her eyes are naturally red. So’s her magic. Can’t communicate that in black and white so I need to tell you that.