It's too much to explain, really, and Zinc very much doubts that Kuja would be particularly pleased to hear some of it. Kuja and Barbet were very different creatures, but there similarities were such that it was a bit impossible for Zinc not to feel some affection for her pretentious opinions and demanding fussiness.

"I'm fond of you."

It was a simple enough encapsulation. She would not claim she loved Kuja, but she did care, and it would be nice to have a moment of contact.