Tora Ziyal is a major character in Star Trek: Deep Space Nine, she is the daughter of the series' primary antagonist Gul Dukat as a result of an affair he had with her mother during the occupation of Bajor despite the animosity between the Bajorans and his people, The Cardassians. Since Ziyal would suffer discrimination from both of her peoples Dukat sent Ziyal and her mother to the neutral planet of Liseppia which went bad when Naprem was killed in an atatck and Ziyal was forced to work in a Breen labour camp.
Deep Space Nine[]
Dukat joined Kira Nerys on a trip to find potential survivors at the camp despite her contempt for him, though she ended up feeling a degree of sympathy after learning about his sadness at Naprem's death. Dukat initially tried to kill Ziyal to save himself from political disgrace but in a rare moment of conscience he spared her, an act which gained him some begrudging respect from Kira.
Ziyal lived on Cardassia for a time though it was not a pleasant experience as most shunned her and felt guilty when Dukat's acceptance of her caused his wife to walk out on him with the rest of her children. Eventually Dukat arranged for Ziyal to live on the station to keep her out of danger during the Cardassian Union's war with the Klingons.
On the station her closest friend was Kira who often acted like a protective big sister towards her. She offered her friendship to Elim Garak, the only other Cardassian living on the station but he tried to keep his distance at first, suspecting she may have been acting on her father's behalf to kill or somehow hurt him as he and Dukat had a tumultuous past. The two did eventually become friends with Ziyal appreciating Garak's kindness though Garak remained adamant that she was mistaken if she thought he was a kind man.
When Dukat arrived back on the station he was furious to discover their relationship and tried to kill Garak over it but he was saved by the intevention of Ferengi Bartender Quark. It turned out Dukat had betrayed the Federation by secretly negotiating a deal with the Dominion to make himself Cardassia's leader. The Dominion attempted to destroy the station and since Ziyal had "betrayed" him by siding with Garak he left her on Deep Space Nine to die. Fortunately the plan to destroy the Bajoran sun was stopped by Kira.
When the station was put under Dominion control Ziyal reconciled with her father when he apologised for overreacting and forgave her "betrayal" despite Kira pointing out to Ziyal that her father was the one who betrayed her. Ziyal had bought into her father's manipulative claims that he was doing what had to be done during the occupation and felt remorse over it so when he refused to pardon Quark's brother Rom for aiding the resistance and instead planned to have him executed for treason she was shocked.
Though she loved her father her morals simply wouldn't let her stand by and watch as the Dominion's corruption continues so she risked her llife, alongside Quark to free, Rom, Kira and Jake Sisko from custsody, allowing them to disable the weapons systems which in turn let Benjamin Sisko regain control of the station.
As Dukat fled, he tried taking Ziyal with him but she refused and revealed what she'd done, shocking him. Though he was furious he couldn't bring himself to hurt her, Sadly this didn't save her as she was then murdered by his right-hand Corat Damar who'd never trusted her. Ziyal's death had a profound impact on Dukat, sending him into a temporary state of insanity to the point even Sisko and the station's security officer Odo felt sorry for him despite having hated the man for years.