Love

Although there is no designated love interest for Kuja in Final Fantasy IX, there's still some room for speculation. Here are a few conceivable ideas:

Garnet
Whether it be romantic interest or not, Kuja does show an awful lot of interest concerning Garnet. He thinks that she is beautiful, and this intrigues him. Kuja is a very vain person, so the fact that he finds Garnet attractive and is of wealth is probably all that matters to him. Though he appears to have a bit of a crush on her, he never acts on this and instead tortures her by controlling her mother and genuinely making her miserable. Because of that, I highly doubt that he ever cared about her for anything more than her looks. Besides, Garnet hates him.

Beatrix
This one could have been possible for a number of reasons. First of all, Kuja and Beatrix start out on the same side. They both oppose Zidane and his group, and they both have connections to Queen Brahne. Second, Beatrix is arguably the most attractive character in Final Fantasy IX (and as we know, attractiveness is important to Kuja). Besides, I think Kuja would be intrigued by her tremendous power as a fighter. Unfortunately, the two of them don't interact much, and in the end, Beatrix isn't exactly on Kuja's side (and becomes interested in Steiner). Ah well, it would have been a neat couple...

And then there is always the suggestion of a romantic connection with Queen Brahne... *coughs*

All content is © Alexandra, adopted by Alicia -- Final Fantasy IX and Kuja are © Square-Enix.