In the mirror universe Saavik was a female Vulcan in the 23rd century. Saavik was a member of Imperial Starfleet and became new-Emperor Spock's protege and student after he sponsored her application to Starfleet. With his help, her career advanced to the point she became Captain of the ISS Enterprise. She also did all she could to help Spock's master plan of destroying the Klingon and Cardassian species by using the entire Vulcan population as sleeper agents, who when activated, would lead a massive uprising against their impending Alliance.
In 2294, Saavik, still captain of the Enterprise, attended a secret meeting on Vulcan's mirror counterpart; the purpose of the meeting was to recruit younger Vulcans into the sleeper agent project. Her arguments in particular led to some Vulcans agreeing to participate, including Tuvok's mirror counterpart. (VOY novel: The Mirror-Scaled Serpent)
When the Alliance formed and began conquering the Terran Empire, Spock asked her to retire from Starfleet and return to Vulcan in preperation for the invasion. Saavik reluctantly agreed. Saavik's last known appearence was when she successfully became a domestic servant in the Cardassian Union and remained undercover for the Vulcan Resistance for many years. (TOS novel: The Sorrows of Empire)
By the later half of the 24th century, it is revealed that Saavik was the Director of an ultra secret organization known as Memory Omega. The group's goal was to overthrow the repressive Alliance and restore freedom to the Terran Empire which had collapsed. This organization and/or it's goals where largely dictated according to an intricate timetable of events that had been designed by Spock. The organization had numerous agents working in sensitive positions throughout known space including agents within the Terran Rebillion and the Kligon Empire. Memory Omega had a number of secret bases that were expertly hidden. Many of these bases were also colonies; housing a diverse population of beings. Saavik, for her part, was an efficent and capable leader. But, her emotional detachment and devotion to Spock's plan caused tension between herself and those around her. Saavik agreed that the group's timetable of events needed to be accelerated to keep pace with changing political events. As such, she authorized her agents to reveal the organization's existance to both to the Terran Rebellion and Calhoun's rebels order for them to work together. Saavik also made the choice to bring Jean-Luc Picard (mirror) into the organization in the capacity of ambassador to the outside world as well as having him assume a senior leadership position with the rebel starship fleet the organization had built out of their own ships, those of the Terran Rebellion and Mackenzie Calhoun (mirror).
Alternate continuity
In a mirror universe where Spock did not kill James T. Kirk's mirror counterpart, Spock and Saavik had a child, T'Val's mirror counterpart. (TOS novel: Spectre)