Poison Ivy and Batman unfortunately share a hot love/hate relationship but maybe Catwoman was more popular, that's why hers wasn't so focused. I kind of thought that the two of them were actually meant to be a couple only if Poison Ivy stops being so fanatical and adopt Batman's views, I think the two can get along. :-P
Poison Ivy is a nature-caring person but she does everything to the extreme. In her crusades, she seems to suffer from passion burns for him. Poison Ivy will always use her charms at him which however, Batman doesn't return them. She of course can't take no for an answer from him so she gives him a kiss. Okay in the Animated Series, he kissed him. I don't think she wanted to poison him. I think she wanted more of him so she teased him with the antidote, if it's an adult angle, I think she wants a night with him. While she seduced Harley Dent for revenge, it seems she lusts after the Batman. In the comics, they've kissed more than once. Perhaps the last thing that may happen is for her to catch him and force him to be his. Well, good luck Poison Ivy. Hee hee.
Too bad though the cartoons didn't write her as Batman obsessed as Catwoman was. But she was in the comics and I ship them as a couple.