IN FICTION EVERY MAIN CHARACTER

Is absolutely vital. As they are the ones who inspire the Audience/Reader to attempt and to Do Great and Important Things.

Yet every Secondary Character is also of enormous import as they are the ones who inspire the Main Character to attempt and to Do Great and Important Things. So in your Own Life, and in Real Life, always be the Main Character, but in the lives of others be a necessary and outstanding Secondary Character.

from Form and Function, The Literate Man’s Guide to Real Life