Grant, Wagner and Breyfogle introduce a new supporting character for Batman in Detective 594 (Winter 1988), the private detective Joe Potato.
The story itself deals with an executive who has been driven mad through his addiction to Ecstasy, and who is seeking out those he feels responsible and killing them. Potato has been hired to stop him, and is one step ahead of Batman when they first run into each other – Potato suspecting that the car the kids have been given is likely dangerous. And, indeed, it explodes. Batman at first thinks Joe is on the side of the killer, but the exploding car makes him realize that more is going on.
Frankly, the story is not the greatest, and perhaps it would have been better to use a fictional drug, or at least one that is more frequently associated with violence. But Joe Potato does look great, in that he looks horrible and suits the world of Gotham.
He would never become a major player in the Batman universe, but Joe Potato would pop up again a few times, always in stories by Grant and Breyfogle, I believe. The drawback to him is that Harvey Bullock is already around, and simply too similar.