For pure literary criticism theory, the place I start is the late Northrop Frye's "The Anatomy of Criticism". As Frye explained it:
"THIS book forced itself on me while I was trying to write something else, and it probably still bears the marks of the reluctance with which a great part of it was composed. After completing a study of William Blake (Fearful Symmetry, 1947), I determined to apply the principles of literary symbolism and Biblical typology which I had learned from Blake to another poet, preferably one who had taken these principles from the critical theories of his own day, instead of working them out by himself as Blake did. I therefore began a study of Spenser’s Faerie Queene, only to discover that in my beginning was my end. The introduction to Spenser became an introduction to the theory of allegory, and that theory obstinately adhered to a much larger theoretical structure. The basis of argument became more and more discursive, and less and less historical and Spenserian. I soon found myself entangled in those parts of criticism that have to do with such words as “myth,” “symbol,” “ritual,” and “archetype,” and my efforts to make sense of these words in various published articles met with enough interest to encourage me to proceed further along these lines. Eventually the theoretical and the practical aspects of the task I had begun completely separated. What is here offered is pure critical theory, and the omission of all specific criticism, even, in three of the four essays, of quotation, is deliberate. The present book seems to me, so far as I can judge at present, to need a complementary volume concerned with practical criticism, a sort of morphology of literary symbolism."

In the process, Frye gropes with such issues as the fact that is no term in English for a general work of prose fiction. He also talks about poetry, but makes clear his canvas is broader, and he uses various terms simply because a vocabulary for poetics exists, but one for prose largely doesn't.

For those who want to sample, there's a decently formatted HTML version taken from an Internet Archive scan up at http://northropfrye-theanatomyofcriticism.blogspot.com/ For an actual published copy, Princeton University Press has it available in paper and electronic form: https://press.princeton.edu/titles/7013.html

Frye's work made me reconsider how I thought about and analyzed literature.
______
Dennis