You can’t really say Gul Dukat ever redeemed himself on Star Trek: Deep Space Nine.
Gul Dukat was the biggest villain, or maybe the most consistent opposition, on Star Trek: Deep Space Nine. While never a main character he was often viewed as being just as integral to the show’s impact on the fanbase as a whole. In fact, of the show’s 173 episodes, Dukat was only ever in 35 episodes. That’s about 20% of the episodes as a whole. For such a small amount of screen time, Dukat really made an impact. That said, to say he had redemption on the show is at best a misguided reading of the series, and at worst a complete failure of his entire story arc.
That’s the argument ScreenRant is making about Gul Dukat’s tenure on the show; that he was somehow “redeemed” during the events of the series. The only problem with that is that redemption fundamentally changes a person, while Dukat never changed.
"Though he’s one of the most salient and omnipresent villains in Deep Space 9, Gul Dukat manages to have a redemption arc towards the end of the series. The complicated nature of the Cardassian’s life makes him not only a compelling character but a complex antagonist who stands out beyond his two-dimensional contemporaries.The leader of the Second Order risks his own principles by helping Benjamin Sisko gather sensitive intelligence during the dominion war, and after his daughter is rescued, he almost becomes a sympathetic character. In Star Trek, the villains are capable of being depicted as open-mindedly as the heroes, for they see no difference in their objectives, preserving the ethos of truth and freedom through their own distorted perspective."
Not a complete redemption.
Yes, Dukat did “soften” over time in the show but most of that had to do with his ostracization from the Cardassians. Because of this, his usual mentality changed and the addition of his half-Cardassian, half-Bajoran daughter didn’t help matters much. While he loved his daughter, that love didn’t stop him from betraying the Federation, aligning with the Dominion, and attempting to invade Deep Space Nine so he could retake Bajor as his own. Her love didn’t soften him.
After her death, he went mad and stopped hiding his hated for Bajorans. That’s when he went further down the rabbit hole of his hatred and aligned himself with the Pah-wraiths. Nothing about his arc redeemed him, if anything it made his rage and hate purer, because he was no longer hiding his contempt for Bajor and its people.
Dukat never got redeemed, and the show was better off for it.