His father, Kotan Pa'Dar was an exarch in a Cardassian settlement on Bajor during the Cardassian occupation. After an attack by the Bajoran resistance in 2362 in which Rugal's mother was killed, Rugal himself was taken by a Cardassian officer attached to Terok Nor to the Tozhat Resettlement Center, while his father believed he was killed in the attack. He was later adopted by the Bajoran Proka Migdal and his wife.
In 2370, Rugal accompanied his family to Deep Space 9. When Elim Garak introduced himself, Rugal attacked him. This led to Rugal becoming the subject of an intense confrontation between the Cardassians and the Bajorans as it was discovered that he had family in Cardassia and accusations were made that his Bajoran parents mistreated him.
In a custody hearing conducted by Commander Benjamin Sisko, it was discovered that Gul Dukat and Kotan Pa'Dar were political enemies. Dukat deliberately had Rugal taken to an orphanage in hopes of someday using this to humiliate his adversary. When Sisko learned of this, he decided to let Pa'Dar take Rugal back to Cardassia, realizing that Pa'Dar had a right to raise his child. (DS9: "Cardassians")