Tokath was a former commander in the Romulan military. In 2346, he was placed in charge of the secret prison camp on Carraya IV, where Klingons captured at Khitomer were sent. When the Romulans decided that the prisoners were no longer useful (they had intended on trading the prisoners back to their people in return for territorial concessions), they were offered release.
The Klingon prisoners, however, did not wish to dishonor their families, and so they asked to stay. Tokath sacrificed his career by allowing this, as he was forced to remain to supervise them to prevent their executions. The arrangement was originally enabled by the Klingon warrior L'Kor, who promised that his people would submit to Tokath in exchange for secrecy, and the Klingons and Romulans learned to co-exist peacefully. Over time, L'Kor and Tokath became friendly and shared the administrative responsibilities of running the camp.
Tokath was married to Gi'ral, one of the Klingons in the camp; together, the two had a daughter, Ba'el. When Worf arrived in 2369, Tokath distrusted him, and refused to let him leave the encampment. Later, when Worf and Ba'el became romantically involved, Tokath disapproved. Tokath had enough and ordered Worf that he must accept life in this peaceful society or die.
When Worf refused to cooperate, Tokath ordered Worf's execution. When Tokath's own daughter, Ba'el, and other Klingons stood up for Worf, Tokath (prompted by his wife) agreed to stand down. Tokath stopped the execution and made arrangements with a supply ship to take the group away. Tokath let Worf and the other Klingons who wished to start a new life leave the encampment, while Worf exacted a promise from these youths to honor their parents by not revealing that their parents were survivors from Khitomer. (TNG: "Birthright, Part II")