I think she was a stepping stone to Kira. Everytime we see Dukat make a decision regarding Ziyal for the positive, it's because Kira is involved. Spare her life when we first meet her, Kira's influence. Get talked into leaving her in the care of Kira when he captured that Klingon warship and get ready for life as a lone renegade, Kira's influence. Ziyal is crushing on Garak, Dukat uses that to berate Kira. Basically, it seems like he only uses his daughter to get closer to Kira. Now, he seems to have real emotions for Ziyal, but after rescuing her from the planet after deciding not to kill her, he does blatantly abandon her or disown her several times. I used to think he really loved his daughter, but the scene that did it in for me was during the dominion occupation of DS9, when he had Damar deliver a dress to Kira for some evening with Dukat. Kira brings back the package with the dress, being plain she doesn't want it, and leaves, Ziyal comes in soon after and admires the dress, and Dukat gives it to her and makes it like he bought it for her all along. Just the sheer disinguity he is capable of. The only thing I can think of that refutes it is his temporary insanity after her death, but I think it can be explained as it occuring right when the offensive collapsed and the Federation retaking DS9, knowing he would be blamed/scapegoated for the overall failure - he used the opportunity to get captured by the humane federation rather than chance being around his socalled allies. Afterall, that same blame got Weyoun 5 killed a little later on. Dukat had such an obsession with Bajoran women in general and playing their savior in particular. While Damar is shown several times using his leader position to bed cardassian women, Dukat was never shown with such a scene - he always was having Bajoran concubines, and Kira was his ultimate prize. Dukat is twisted enough, that had Ziyal lived, I wouldn't be surprised that he got off on his daughter's hero worship of him to fulfill that savior fantasy and eventually would have bedded her himself, as some type of weird compromise between a political correct Cardassian he needs and Bajoran lover he wants. Might have explained his rage towards her affection to Garak beyond a mere unexplained family dispute.