I love a good roller coaster ride of a plot with stomach dropping plummets and twists that you never anticipated but that ultimately still feel grounded in the story.
In one story I've been working on, I originally intended to have as a surprise reveal at the climax that one of my characters was secretly working for the villains. Eventually, though, I realized that much of the story would be impenetrable unless the reader understood prior to the climax what the character's motivations were and what the stakes were for him personally. That was why I decided to let the reader in on the secret from the beginning and play off the tension of an enemy being present among the main characters without their knowing it.
In one story I've been working on, I originally intended to have as a surprise reveal at the climax that one of my characters was secretly working for the villains. Eventually, though, I realized that much of the story would be impenetrable unless the reader understood prior to the climax what the character's motivations were and what the stakes were for him personally. That was why I decided to let the reader in on the secret from the beginning and play off the tension of an enemy being present among the main characters without their knowing it.