Psychological Doubling
Pairing the main character with a second character who mirrors them. The double shows what the hero wants, fears or secretly is.
Venus in Fur
Vanda the actress and Wanda the character in the play work as mirrors. As Vanda reads, she starts to speak for the character, and Thomas increasingly identifies with the male lead.
The Lighthouse
Thomas Wake and Ephraim Winslow start as master and servant. They end up impossible to tell apart in their madness and their myth-making. Eggers builds this doubling as a merger. It starts as a chain of command. Under the pressure of the island, it becomes a single mind living in 2 bodies.

