(written from a Production point of view)
Star Trek: Dark Passions is a two-novel series, written by Susan Wright and published by Pocket Books in 2001. The series takes place entirely in the mirror universe, with particular focus on female characters from Star Trek: The Next Generation, Star Trek: Deep Space Nine, and Star Trek: Voyager.
The original concept came from Pocket editor John Ordover, who pitched to Wright a "'bad girls' of Trek" idea. Wright's story was originally devised as a single novel, the series soon being expanded to a duology (a preferred marketing strategy of Ordover's editorial era). (Voyages of Imagination, p. 453)