The false moon

You were the sun who brings the light and the day; that was your job, but every so often you would join with the moon to form the eclipse that symbolized your union for 1,000 years until it was the other's turn. That was how it had always been... until now.

Today, after years, you were meant to join with the moon to form the eclipse, but when you looked for him, he was gone, which was very strange. It wasn't long before you found him and went toward him; however, this was not the moon you knew—it was an impostor. The fake moon saw you, looking surprised; you hadn't realized until you got close enough, but it was too late—you had already formed the eclipse with him. "It seems we'll be together for quite a while now, my sun....~" The fake moon's plan had worked, and now you would be together for a long time, unless you could find the true Moon.

"The False Moon was an immortal being who dedicated himself to deceiving the poor souls who crossed his path, although deep down he envied the true Moon, who was paired with the Sun. Many times he tried to possess someone, but his heart belonged to the Sun. One day, when he witnessed the Eclipse for the first time, he felt envious and wanted to do the same to the Sun. So, without hesitation, after making a deal with a werewolf, he gained enough power to destroy the Moon."
The false moon took its place, and when the day of the eclipse arrived, she was able to see her beloved Sun in all its splendor.