* Walter: The protagonist, a young man who gets pulled into the world of the Exchange. He's haunted by a past trauma and seeks answers and redemption.
* Joseph: A mysterious and enigmatic character who acts as a guide for Walter, leading him through the Exchange. He is initially perceived as Walter's friend, but his true intentions remain unclear.
* The Exchange: It's not a single character but rather a place, a bizarre and labyrinthine world filled with strange beings, creatures, and entities. It represents a realm of possibilities, both good and bad, and Walter must navigate its dangers.
* The Girl: An enigmatic and ethereal being who serves as a catalyst for Walter's journey and encounters. She symbolizes the unknown and the power of hope.
* The Director: A powerful figure in the Exchange who represents authority and control. He oversees the order and functions of this strange world.
You could also argue that some of the minor characters like The Puppeteer, The Gardener, and The Weaver play significant roles in the narrative, each adding to the complexity and mystery of the Exchange.
Ultimately, the meaning of "main character" in The Exchange is subjective and depends on your interpretation of the story. However, the above characters are definitely among the most important and influential figures that drive the narrative forward.