I'll think and suggest some more, but one obvious starting place (to me)
is reading Aristotle's Poetics next to his Rhetoric. Since the poetics
defines tragedy by its rhetorical effect on its audience (i.e., a tragedy
is a play that evokes a catharsis of pity, fear, and other such
emotions), it is a kind of rhetoric of tragedy. (N.B., All those rules
people remember about how a construct a tragedy, Aristotle supports by
asserting that they are most likely to evoke the defining
catharsis--formalism was, in my opinion, a later misreading).