For PinkRobins adoptables: http://www.dolldivine.com/Anime/PinkRobin-3009659
Note: when I first posted this story, I didn't have names for these characters, so I left them blank. I came up with some, so I changed it. In case you were confused :)
Berm has always protected her younger sister, Gully, from danger. So, when an enchanted cave gives the former the power to turn into a Magical Girl, she keeps it a secret from her sister. This puts a strain on their relationship, with Berm always having to leave Gully on a moments notice to attend to supernatural crises, and never being able to tell her the truth about it. But, as long as it kept her sister away from her dangerous magical world, it was worth it to her.
Until one night, when Gully decided to secretly follow Berm on one of her excursions...all the way into the enchanted cave. When the two of them stepped inside, magic filled the air, and Gully was granted the same powers as her sister. (Or, the same kind of powers, anyway-they're really more like opposite sides of a coin.) Furthermore, Berm's own powers no longer seem to work properly without Gully's precense.
From that point on, Berm grudgingly became Gully's mentor and partner in all things magical. Will they be able to work together, despite their personal issues? Why did they become Magical Girls, with uncannily matching powers, anyway? And just what is the story on that cave?...