Prologue: Once upon a time...
Once upon a time, in a fairytale-esque land called Equestria, there lived a Pegasus named Princess Melodia. Unlike other pegasi however, Melodia had been born with a powerful magic. Many scholars and unicorns tried to find some explanation as to how this could be, but none were found. Queen Celestia, an alicorn and ruler of Canterlot to the filly under her wing and helped her to learn to control her powers. Believing that they could bring great things for not just Melodia but for all of Equestria. As she grew, Melodia began to notice changes in her magic. It's once shining light had lost its brilliance and was starting to grow darker. Fearing the worst, she sought counsel from Queen Celestia.
Queen Celestia did her best to console the poor Pegasus, but she too was also worried of this change. For Melodia's magic reflected off her heart, and right now, it seemed as though Melodia's heart was experiencing some sort of turmoil. The alicorn queen told Melodia that her magic would right itself once her heart overcame this turmoil. Melodia thanked her and returned to her kingdom at the far corner of the land. The turmoil in Melodia's heart stemmed from the anxious and lonely feelings that had developed in her heart. Though she was a beautiful princess who worked hard to become a noble queen, her subjects were suspicious of her mysterious magic and kept their distance to avoid upsetting her or getting on her bad side. Things only grew worse when Melodia's father, the king, died in battle, and she had to take his place as queen. Broken hearted over his death, Melodia closed off her heart to anypony else to keep it from breaking anymore.
At the same time, Melodia saw that her magic had indeed gotten a bit stronger, only it was darker than before. Melodia paid no mind to this and continued to practice her skills.
Queen Celestia grew worried for the Pegasus who'd closed herself off from everypony, she decided to pay her a visit and see how she was doing. What she found, was unexpected. The magic Melodia now had was black magic, a forbidden and dark power that grew stronger as Melodia's heart became harder. Celestia tried to convince Queen Melodia to abandon her magical studies lest she be consumed by the corruptive magic and to open up her heart once more, hoping to save the mare from herself. But the black magic had already begun to warp her mind, and refused Celestia's pleas, ordering her to leave her castle and never return.
Just as Celestia feared, the black magic had taken over Melodia and made her bent on conquering all of Equestria. She even gave herself the title of, 'The Queen of Evil'. Queen Melodia spread her terror and darkness across the land, nearly succeeding in taking complete control. That is, until she was stopped by Queen Celestia and her sister Princess Luna. A lengthy battle was waged between the three powerful ponies. The sky darkened as the three clashed, casting spells and battling in the air, until Melodia was finally weakened and at the mercy of the royal sisters.
Feeling pity toward the Pegasus who'd she once thought of as a friend, Celestia banished Melodia to the confines of her own kingdom, and a powerful barrier was erected to keep Melodia from ever getting out. Angered by this, Melodia vowed to one day exact revenge upon them and the rest of Equestria. Queen Melodia delved deeper into her studies of the black magic, preparing and planning for when she could escape from her prison. No matter what, she would get out. And everypony would feel the pain that she'd felt.