(coexisting on another dimensional plane)
Elim Garak was the second-in-command of the Klingon-Cardassian Alliance outpost Terok Nor in the Bajoran sector, serving under Intendant Kira Nerys. Garak chafed under Kira's command, constantly wishing to set violent and brutal examples to quell minor resistance from the Terran slaves who were working in the ore processing facilities on the station.
Garak was constantly hatching plots to kill the Intendant and take command of the station himself - plots that were always transparent and unsuccessful. When the Kira Nerys of another universe suddenly arrived on the station in 2370, Garak saw the opportunity to have the Intendant killed, and have her replaced by the parallel Kira. Kira would then resign her post, leaving Garak in charge of the station. However, Garak's plot never came to fruition, because Kira left the station before he could have the Intendant "disappear". (DS9: "Crossover")
The next year, Garak relished the chance to make an "example" of Terran Rebellion leader Benjamin Sisko, but the Intendant was so pleased to have her former lover back at her side that she told Garak to leave him alone. When Rom came to the station offering intelligence on Sisko, Garak had him tortured into revealing the plot to help Jennifer Sisko escape from the station, and then had him killed. (DS9: "Through the Looking Glass")
When the rebels attacked and captured Terok Nor from the Alliance in 2372, Garak was the only officer to escape the destruction unharmed. He was quickly captured by Regent Worf, however, who placed him in a dog collar as humiliation for the defeat. However, Garak managed to deftly deflect blame for the loss of the station onto Intendant Kira, and further convinced the Regent that she was to blame for the defeat at the Battle of Terok Nor. (DS9: "Shattered Mirror")
Worf and Garak finally managed to capture the Intendant in 2375, but she managed to bargain for her life by convincing the Regent to use Grand Nagus Zek as a bargaining chip to obtain a cloaking device from the primary universe - a technology that the Alliance did not possess. Garak was greatly disappointed that he was not able to execute the Intendant, but he planned to execute Zek, Quark, and Rom instead. However, the Ferengi managed to deflect Garak's attention by pointing out that his plans were amateurish - "our Garak would have relished the chance to actually interrogate his subjects to learn their secrets". The mirror-Garak, however, was more interested in simply killing his prisoners. Garak was distracted long enough for Ezri Tigan to sneak up on him and inject him with the same hypospray that he was about to use on Quark.