Chandler made heavy use of the parallel universe plot device throughout his career, with many Grimes stories involving characters briefly crossing over into other realities. In "The Dark Dimensions", which is set at a point in space where various realities meet, Grimes (the Rim World commodore), meets a second John Grimes who is still in the Federation Survey Service, as well as characters from the Empress Irene books and Poul Anderson's Dominic Flandry.
