Prometheus Unbound and The Cenci are the high watermark of Shelley's annus mirabilis. Earl Wasserman views them as representing ‘the antinomies of the skeptical contest as it was waged in Shelley's own mind’, and his letters create a similar sense of the pair of dramas as expressive of binaries, with Prometheus Unbound firmly demarcated as for ‘the elect’ (Letters: PBS II . p. 200) where The Cenci is ‘calculated to produce a very popular effect’ (Letters: PBS II . pp. 116–17). Despite this apparent division, in which popularity appears to be associated with ‘sad reality’ (Dedication to The Cenci, p. 314) and the poetry of the elect aligned with ‘beautiful idealisms’ (Preface to Prometheus Unbound, p. 232), Shelley does not offer unfettered idealism in Prometheus Unbound, nor does he merely depict ‘sad reality’ in The Cenci. The letters create a difficult doubling between the poetical dramas, and Shelley's letter to Thomas Love Peacock of 6 November 1818 in particular offers a suggestive perspective through its fascination with the poet's response to tyranny. Shelley's preoccupation with embodying power struggle in language remains constant in The Cenci and Prometheus Unbound.

Shelley's letter to Peacock, written during his composition of Prometheus Unbound and prior to writing The Cenci, sees him relate his visit to the public library in Ferrara Cathedral. His primary fascination was withAriosto and Tasso's writings (Letters: PBS II . p. 46), but Shelley lingered over Tasso's desperate entreaties to his jailor, the Duke of Ferrara:

This preoccupation with the poet's attempt to survive tyrannical authority is mirrored in Shelley's imaginative writing. The tensions in both The Cenci and Prometheus Unbound centre on the poet's role in a world where powerful authority figures persecute their victims, Beatrice Cenci delineating society as divided between these binaries.