DIS: The Dark Crystal Fable

Once upon a time, there was no magic in the kingdom. But one day, a wizard came and mystified many of the kingdom's residents. The wizard claimed that anyone could have magic powers, all they had to do was create a potion that would grant the drinker far more powerful magic than the wizard had. Soon enough, nearly everyone was searching for the potion's recipe so they too could wield magic.
Two sisters went out to find the potion's recipe. The two sisters, Theodora and Evanora by name, quickly found the recipe and made the potion together.
“When we have magic powers, we will use them to help others.” Evanora told her sister before they drank the potion for the first time.
“I agree.” Theodora nodded.
But the potion did not work right away. The wizard failed to tell anyone that the potion was like a medicine; you had to keep using it in order for magic powers to develop. So the two sister continued to drink the potion for three long years. Then one day, Theodora woke up with a dark crystal in her hand. The crystal was pitch black in color, but if she looked close enough, Theodora could have sworn that something flowed within the crystal similar to water or smoke... or both. It amazed her, and it scared her. Quickly, she went to Evanora. But her sister had never seen anything like it and could offer no help.
Later on, Theodora realized that she could now use magic. But the power of the magic made her do unspeakable things to everyone, including her sister. The power that flowed in Theodora made her insane, and one day she disappeared. No one could find her, but by then, no one loved her anymore because of the horrible things she had done to others. Now alone, Evanora grieved over the loss of her sister, only fearing the worse.
In time, Evanora came to hate the wizard who introduced the potion to the kingdom. One day, she brewed over the wizard with a great hatred that smoke started to form from her hands. In an act that was against her free will, Evanora's hands cupped together and the smoke formed into the same dark crystal that Theodora had once produced. Horrified that she may end up like her sister, Evanora tried to destroy the crystal with her own magic power, but it was useless. Then, out of nowhere, the wizard appeared in front of Evanora.
“You did this!” Evanora cried out to him. “How could you have let this happen?”
“I let nothing happen.” the wizard told her. “You and your sister have a strong will, which is why your sister's magic was powerful. The crystal is only a physical manifestation of that power, however dark or beautiful it may be.”
“But now my sister is gone!” Evanora yelled.
“Only because her will was not strong enough to create beauty from the destruction.” the wizard told her calmly. “The potion is stronger than my magic power because it was based off of mine, but then added on to, using your wills and abilities. You, however, can turn the tables of the dark power the crystal symbolizes.”
“How?” Evanora asked, the desperation in her voice was almost unfamiliar to her.
“It will take more will than what you believe your have.” the wizard admitted. “It will involve trusting one you may never think you could have trusted, or you may have to face a challenge where the angel of death looks you in the eye. In whatever way you choose to redeem the darkness, it will be hard, but not impossible.”
With that, the wizard disappeared without a trace, leaving Evanora alone with the chance to change fate...