Prompt: Write a short story about a man who discovers a magical portal

John was walking through the city when he happened to notice a strange portal in the sky. He walked up to it and touched it, and suddenly he was transported to a strange world. in this world, John found that he had the power to transform into any creature he wanted. John quickly discovered that he had the power to become a dragon, and he began to terrorize the inhabitants of this world. John was finally captured and imprisoned by the king of this world, who forced him to reveal the location of the portal. John refused to tell the king anything, and he was eventually executed. But John’s death didn’t stop him from fulfilling his destiny; he now resides in the magical portal, terrorizing other worlds as a dragon forever.