internal monologue
Noun
Meaning
A person's "inner voice" which provides a running verbal monologue of what they are thinking, important in planning, problem solving, self-reflection, etc.
Synonym: self-talk
(literature) A representation of someone's thoughts as articulated. (Can we add an example for this sense?)
Source: en.wiktionary.orgSynonyms
Examples
Plot exposition that can be gently wound out by the authorial voice and internal monologue of a character in the length of a page has to be delivered in a matter of seconds on the stage.
My thing is, I like playing guys who have a really interesting internal monologue.