I had touched on Bat Boy in my Camp Horror Mad Libs, comparing it to Reefer Madness and Little Shop of Horrors. Like Audrey II, Edgar can only survive on blood. Like Jimmy, Edgar is brought down by his own addictions.
The element Bat Boy introduces apart from the others is the chorus of cruel townsfolk who push Edgar to his downfall. Edgar is less Dracula and more Frankenstein, a tragic creature who is denied love by his appearance.
Scott Miller writes:
"Many musicals are built on the concept of Assimilate Or Be Removed. The central character in many musicals must make a choice to either change in certain ways in order to join the existing community or he must be removed from that community either by leaving or by dying. In The Music Man, Harold Hill turns legit in order to join the River City community. In Sweeney Todd, Jesus Christ Superstar, and Evita, the main characters will not change so they must be removed, by death."
Which side does Edgar fall on? The show is still being produced so you'll have to see a production (or listen to one of the terrific cast albums) to learn.