You all have such exciting ideas... I was thinking a Lazy cousin of Zatanna, who knows more magic than she did, but could not be bothered to use it, because he has very little stamina. He also told her that if she ever disappeared then she better not think he was actually going to come look for her. I am just imagining his motivation - sitting at the opera one evening, and a super-villain interrupting the main aria - which pisses him off, leading to him reluctantly actually doing something about the crime.