Quark opened an establishment on Terok Nor called, Quark's Bar, Grill, Gaming House and Holosuite Arcade. After the station was taken over by the Federation and Bajoran Militia Quark was convinced to remain.
In early 2373, Quark fought and defeated the Klingon Thopok in honourable combat after Thopok took exception to Quark's interest in Grilka. Unknown to Thopok and Grilka Quark was puppeted by Worf during the battle.
During the Dominion occupation of the station Quark assisted the resistance cell on the station delivering them intelligence he gathered. He later broke the members of the cell from the station's holding cells allowing them to disable the station's weapons.
In an alternate universe where the Dominion won the Dominion War, Quark avoided execution for his part in freeing several prisoners on the station during Starfleet's Operation Return. This was partly due to Tora Ziyal saying she forced Quark into helping her and a plea from Grand Nagus Zek. However, the death of Ziyal, Rom and Nog saw Quark leave the station and return to Ferenginar. He left his bar under Morn's management before eventually selling it him.