In literature, what is a subject?

You may be talking about a different kind of subject but I think this is what you were talking about:

A subject is the first part in a sentence about which the second part, the predicate, tells something. The subject performs an action, or indicates what or whom the sentence is about.

In literature, the subject is the main topic that serves as the basis of a story, poem, song, paper, essay or any piece of writing. Examples of subjects are war, love, hate, marriage, censorship, and identity. It is often confused with the theme, but they are not the same. The theme is a message or moral lesson that a piece of writing conveys about a topic. For example, the subject of a story may be “freedom” and the theme may be “all good things are wild and free.”

the answer is not

what is the question?