Retellings and Sequels/Prequels to Existing Novels by Other Writers - Your favourites (or favourite train wrecks)

The Penelopiad. Anno Dracula. Return to the Secret Garden. Lydia and Kitty Kill Mr Wickham.*

This is book chat about that thing where authors take a pass at a pre-existing work by another author, be it a revisionist adaptation (telling the story from another character's perspective, developing/introducing new themes…