In 2363 she worked as a correspondent with the Cardassian Communication Service on Terok Nor. During her stay, she became romantically involved with Quark, owner of Quark's, the station's gambling establishment. She ended the relationship when he used her access codes to steal money from the Cardassian government. However, she still harbored feelings for him as late as 2370. She also showed sympathy to the Bajoran inhabitants of the station.
In 2370, she was working as a professor, teaching political ethics, while covertly functioning as a member of the Cardassian dissident movement, along with her "students" Hogue and Rekelen. She encountered Quark again at Deep Space 9 while fleeing the Cardassian Central Command. Despite her denial of any feelings for him, he insisted on being with her, either her staying on the station or going with her, leaving his bar behind. He offered her companions a cloaking device to escape in exchange for her to stay with him. She did not believe him, and, when she refused, even shot him when he refused to give it anyway. Afterward, she finally expressed her feelings for him.
The Bajoran Provisional Government intended to exchange her and her companions for Bajoran prisoners, leading Odo to arrest them. Quark successfully convinced him to free them and facilitated their escape from a Cardassian warship sent to DS9 to capture her and her students. Ultimately, Professor Lang was more dedicated to her students and the Cardassian Underground than to Quark, so she left with them, though she promised Quark they would meet again one day. (DS9: "Profit and Loss")