Well, the main character is likely your Poptropica avatar. However, there might also be other important non - playable characters like a local who warns you about the haunted place or a ghostly figure that gives you hints throughout the story. The avatar is the central figure who has to interact with the environment and these other characters to drive the story forward in the Ghost Story part of Poptropica.
In Poptropica Ghost Story, the main character is predominantly the player - created Poptropica character. This character is thrust into the world of the ghost story and has to be brave and resourceful. There could also be side characters such as an old caretaker of a haunted building who might share some of the backstory. And perhaps a young spirit who was wronged in the past and whose story needs to be uncovered. These characters, along with the main avatar, help to create a more immersive and engaging ghost story within the Poptropica universe.