In the mirror universe, Bareil Antos is a male Bajoran who was a thief and con artist who lived during the 24th century. Bareil led a violent and destructive life, often stealing to survive or make a profit. He believed this was what he was destined for as he believed he would "somehow ruin everything good that comes my way".
In 2374, he had become the latest consort and plaything of Intendant Kira Nerys and she conspired with him to journey to the primary universe and steal the Orb of Prophecy and Change and use its religious effect on their Bajor to convince the population to unite against the Klingon-Cardassian Alliance, with themselves as their leaders.
He apparently has ties to the Terran Rebellion, as one of the rebels owed him a favor and gave him a multidimensional transporter device to go between their universes, but apparently these ties were not strong enough to openly fight the Alliance.
While on his mission, Intendant Kira's primary universe counterpart, Major Kira Nerys, had convinced Bareil to change for the better and, in the end he couldn't go through with the Intendant's plan to steal the Orb. He eventually left the Orb on Deep Space 9 before returning to the mirror universe. (DS9 episode: "Resurrection")
Bareil was later mentioned by the Intendant as having joined the Terran Rebellion full-time, presumably inspired by Major Kira to fight for something worth dying for. (DS9 - Mirror Universe novella: Saturn's Children)