I would like to see a villain that's related to Poison Ivy but is her total opposite. I keep thinking it would be cool if she had a son she abandoned and said son grew up to be like a cybernetic technopath that just hated nature and was committed to making the Earth into a lifeless massive machine. The reason I like this idea is Ivy is shown to hate humans and men especially so it would be fun to see a character that is her reverse but exists because she ultimately created him like it comes out she abused and or neglected him and ultimately abandoned him as a child and he grew up to just hate her and his hatred evolved into a hatred of nature and became a drive to ascend into what he saw as a perfect being through machines. One of the reasons I like this idea is that it takes everything Poison Ivy claims to be about and slaps her in the face especially if said villain basically wanted what she wanted but with machines and not plants and I just love the idea of Batman or some other member of the Bat Family being there to point out to her that she ultimately created a villain that is her worst nightmare since I imagine a planet with nothing but machines would terrify her.
At the same time I like this idea for a Batman villain becomes I can see this villain making arguments like "Machines do not make mistakes they enforce and represent order at it's purest where as nature is cruel, fickle, incapable of love, and has only created a crime ridden world unworthy of salvation." and it would be interesting to see Batman face a villain as cold and logical as he himself can be and at the same time I think a character like this would make for a good arc especially if it centered around Poison Ivy.