My idea for a third Batman reboot involved Bruce Wayne attempting to purge his dark and vengeful side by seeking the help of Edward O'Nigma (In reality a malevolent Leprechaun known as "The Riddler").
The Riddler removes Bruces Dark Side and they lock it in Wayne Manor's Wine Cellar, however it escapes and inhabits the body of the Wayne Family Physician Dr. Kirk Langstrom.
Realizing he no longer has the same passion for fighting crime as he did when he had his vengeful side Bruce gives up being Batman and begins some monumental charity work.
Meanwhile, his Dark Side in Langstrom's body begins wreaking havoc on Gotham city and Bruce realizes he must become Batman again to fight it.
After a long and hard battle with the possessed Langstrom, Bruce's dark essence leaves Langstrom's body, and fights Bruce on it's own. (Bruce is the only one who can interact with it without becoming a host.)
Bruce realizes that the only way to defeat it is to accept it back into himself.
This version of Man-Bat would appear as a dark, bat-shaped shroud with lightning balls for eyes. When possessed by it Langstrom would turn into a human-bat hybrid closer to the one in the comics.