beta
1. Dude really got sent into the book and became the main character himself
2. Maybe he's reliving his past life (not likely)
3. Or he just really does have DID (dissociative identity disorder) and thinking of himself as the actual character in the book he read.
Which is pretty weird cause i just learned yesterday it's a real thing where people with DID can literally think of themselves as another alter of a fictional character which is called a fictive interacting with other fictional characters? I don't know how that works but it's really complicated