Self-Insert

Self-Insert 

Refers to a story that features an original character who deliberately and purposefully represents the author, for they have actually written themselves directly into the story to interact with the characters. Some self-inserts may be written from the second-person POV to allow any Reader to imagine themselves as the character as well. Most often used for humour, as a parody or to provide commentary, but may also be done seriously. Authors who insert themselves into the story need to be careful not to cross the very thin line that separates their original character from a Mary-Sue, the idealized and non-realistic representation of what the author wishes to be. A feat that is no small challenge.