Literary sub-genre: Novel or play retells a classic from the perspective of a secondary character or characters. The new story tracks the the original but shifts some of its action offstage. The two versions intertwine, each now commenting on the other.
Examples:
Rosencrantz and Guildenstern Are Dead (Tom Stoppard).
James (Percival Everett).
@JamesGleick Somewhat along those lines – the Alexandria Quartet’s first three books. A friend of mine,Juli Crockett, has written some works along those lines: [or the whale], riffing off Moby Dick, The Dawn of Quixote, and Orpheus Crawling…
@JamesGleick Australian author Margo Lanagan has done several fairy tale retellings. The Goosle is a dark, rich version of Hansel and Gretel. Tender Morsels retells Snow White and Rose Red. Both are unsettling but ultimately inspiring explorations of what it means to be human. https://australianfairytalesociety.org/publications-margo-lanagan/
@JamesGleick A Thousand Ships, by Natalie Haynes, tells the story of the Trojan War from the perspective of the women (except, maybe that one woman…), starting, of course, with Homer’s muse.
Also want to echo others who mentioned Madeline Miller’s books; Circe in particular.
@JamesGleick The Simpsons episode "You Only Move Twice" is a Bond movie from the perspective of an oblivious employee of the villain (Homer, of course).
Marvels, by Kurt Busiek and Alex Ross, looks at the first 40 years or so of Marvel Comics from the perspective of a photojournalist at the Daily Bugle.
@JamesGleick C. S. Lewis's Till We Have Faces powerfully tells the Cupid and Psyche myth from Psyche's "jealous" sister's perspective.
All his life, he felt that Apuleius got one key thing wrong, so he changed one key idea to make it psychologically compelling. To do that effectively, he had to tell it from the sister's perspective.
"Finn" by Jon Clinch tells the story of Huck Finn's father. It tracks but barely interacts, as he did.
It is really good, but really dark and brutal. So much that it's hard to say I liked it. It's been a while, but I don't think I'd say it was gratuitous, which tends to make me mad.
"Marley" by the same author, but I haven't read it.