ugh i feel like this is calling for a Rose Red and Snow White retelling, but i can't quite get there.
Once upon a time there were two sisters, and they decided to seek their fortunes in the world.
"I'll go east," said Blackberry.
"Then I'll go west," said Strawberry.
But before they left, they each breathed on a mirror and left it shining, and said to each other, "if my mirror should go dark, know that misfortune has befallen me."
So Blackberry chased the rising sun, and fought a dragon with three heads, and each head promised wealth and power and love as she fought it. And when she'd slain the dragon, the people of the kingdom came out and proclaimed her Queen.
But Strawberry found in the west nothing of note; she traveled around the world, until she came to Blackberry's kingdom in the east. And she looked at Blackberry's mirror, and she saw that it had gone dark.
"But how can that be?" said Strawberry, "since she is queen?"
And Strawberry went to the marketplace, and there she saw her sister pass by, all in the garb of a queen; but behind her was a man in black, and in his hand was a knife.
So Strawberry rushed forward and tackled him to the ground, and Blackberry was saved; and when she came to reward the one who'd saved her, she saw that it was her own sister Strawberry, despite her worn clothes and her dusty face and her disordered hair. And she raised her up and raised up too a throne beside her own, and made Strawberry queen as well.
And if they are not dead, they are reigning yet.