Some common examples of names that are initials in fiction are J.D. Salinger's 'Catcher in the Rye' where the main character is Holden Caulfield. The initials can add an air of mystery. They make the character seem more aloof or unique. It also gives the author a way to create a distinct identity for the character without using a full, common name.
To write good initials in a novel, first, think about what key elements or themes you want to represent. Make them distinct and easy to understand. Also, consider how they fit into the overall narrative structure.
You can usually add your initials in a corner of the comic page using a pen or a digital drawing tool. Just make sure it's legible and doesn't interfere with the art.
In 'A Tale of Two Cities' by Charles Dickens, there's Sydney Carton who is often referred to as S. Carton in some passages. This use of initials gives him a sense of being a bit more of an enigma. He is a complex character, and the initials can add to that sense of mystery and aloofness that surrounds him.