It sounds like you are referring to a retelling or adaptation of a classic literary work from a different perspective. This can often involve reimagining the story through the eyes of a minor character, exploring untold aspects of the original narrative, or addressing themes from a modern or alternative viewpoint.
For example, works like "Wide Sargasso Sea" by Jean Rhys retell the story of "Jane Eyre" from the perspective of Bertha Mason, providing insight into her character and experiences. Similarly, "The Penelopiad" by Margaret Atwood reinterprets the story of "The Odyssey" through the voice of Penelope.
These adaptations allow authors to explore deeper themes, provide commentary on the original work, and engage readers with fresh interpretations of well-known stories.