While the demigods are relaxing in the midst of having their vacation, they spot a mysterious flying bison in the sky. There, they meet Avatar Aang together with his friends. They discover more about their worlds and that Percy is actually called a... water bender ? Disclaimer: I do not own any of the characters in this story. They are from Rick Riordan's Heroes of Olympus series and Nickelodeon's Avatar: The Legend of Aang