This is one thing I like in some interpretations of Ivy. Not DCSHG Ivy, but Ivies like DCAU Ivy. This idea of vanity, of narcissism. Ivy wants to wipe out all human life, but she conveniently leaves out the fact that SHE'S human, or she used to be. Like almost all genocidal maniacs, she makes an exception for herself. And of course in a lot of continuities she takes a certain amount of pride in her appearance, as well as her ability to sway men to her just from sex appeal. I like the idea of Ivy as being very vain, and it being both a character trait and a flaw that can be exploited (by Batman and others).