Once upon a time, a young demon came to the human world on a whim. She met a human and her heart beat fast at witnessing his cheerful, optimistic personality, even in the face of such a strange and powerful being. He greeted her like one would to any other person. His feelings were so contagious that she often found herself smiling with him. She wanted to always feel that way. And so, she came to the human world more and more, and eventually, he fell in love with her too. Nothing seemed wrong until the young demon told her mother of her plans to marry the human and stay in his world until his death.
The mother was worried. Humans were rarely kind to beings that are interpreted as inferior or evil. She acknowledged the loving human's kindness, but she could not for the rest of his family. The mother demon told her daughter, "You can stay with him, but on three conditions: one is that you take human form at all times; second is no other person outside the magical world is to know the truth of your heritage; and three, if you bear child is born, they should have the right to choose the world of magic or the world of humans."
The young demon quickly agreed, and she essentially gave up her powers to live with her human lover. They stayed together in happiness for many years.
A beautiful mother always told her daughter this story on the parent's anniversary. Her daughter's name is Marceline Diaz, and little did she know that her life was about to become a fairytale.