Originally Posted by
John Venus
TDK Returns was incredibly successful. O'Neill and Englehart laid the groundwork for a darker Batman but it was Miller who took it to it's most extreme. I heard from fans at the time that it even made the local news. Then the 1989 Batman movie happened and it was a major turning point in the general public's perception of Batman. Up until that point, the dominant image of Batman was that of Adam West's Batman. A darker, radically different Batman was new and fresh at the time and it even sparked the 'Batmania' leading up to it's release and aftermath. '89 Batman made it's own contribution to blockbuster filmmaking, particularly in tying films and merchandising. It even lead to several darker films inspired or based on comics like Sam Raimi's Darkman and the 90's Dick Tracy movie.
Then Batman hit animation and it turned out to be a huge turning point for that as well. Imagine watching something like Robocop animated show then being hit by something like Batman: The Animated Series that took on a darker, more mature approach to story telling and opened the doors for shows like The Real Adventures Of Johnny Quest, Swat Kats and Gargoyles. Batman wasn't solely responsible for this of course, Simpsons and the rise of anime also played a part in it but Batman certainly helped.
On the comics side, under Denny O'Neil's editorial role in the 90's, the Bat Books expanded to include multiple titles under it's umbrella. Catwoman, Nightwing, Robin and BOP had titles that ran into the 100's. It set the mold for Bat titles and Bat events that they follow to this day.
Even after the Batman movie franchise hit a lull period after Batman & Robin, they still gave Batman a chance again and he made banks with TDK.
Then Batman hit big in Arkham Games which had a lot of people who worked on B:TAS (Dini, Conroy and Hamill) involved. Then the DTV movies adaptated his best stories helped pick up new fanboys. Jason Todd's popularity is significantly owed to the Under The Red Hood movie which was later adapted to the Titans show and the Arkham Games.
Also, as others have mentioned, Batman has a high degree of consistency in his mythology. Even with the consistent reboots. Bruce Wayne's parents were murdered in Crime Alley by Joe Chill, Alfred raised him (this wasn't the case in Golden and Silver Age but it doesn't matter now, Alfred *is* Bruce's father figure now), Gordon is his primary ally in the police force, Dick was the first Robin, Jason died at Joker's hand, Tim is the third Robin and Damian is his biological son by Talia. It's not like the WW mythology where Diana is born from clay by the Goddesses/daughter of Zeus, Cassie is either child/grandchild of Zeus or that weird Nu52 origin, Donna's multiple choice origin, Nubia being other WW's twin sister/just another Amazon or depending on the adaptation, Hippolyta has been with Zeus, Hades and Ares. That's without getting in how to ridiculously fractured the Flash fandom is post Flash Rebirth or how you have multiple GL's vying for panel time but DC at this point can only publish one book. But hey, if you think that's bad, try being a fan of the Hawks. Any of them. Or being a fan of the JSA. Or the Titans. Or worse, the Legion of Superheroes.
The high degree of success is helped by the fact that the same people have worked for years on Batman. Denny O'Neill was a writer and later editor for Batman for two solid decades. He put Frank Miller on Year One. Producer Michael Uslan has his name attached to every single Batman adaptation since the '89 Batman. Bruce Timm has worked on every single Batman cartoon with the exception of 'The Batman' and 'Batman: The Brave and the Bold'. Though even those shows had DCAU alumns like Alan Burnett and James Tucker respectively. Dini, who wrote B:TAS also worked on the Arkham Games.
Also, the Batman comics takes advantage of the *whole* comic book canon from the first Batman to the most recent one. Stories like the 'Case of the Chemical Syndicate' gets retellings every other anniversary. There aren't weird cut off points like Post Crisis, Nu52 and Rebirth like there are for other characters and every character has a place in the mythos and usually with their own book too. Even a once minor supporting character like Lucius Fox now has a fleshed out extended family who have carried their own books and even Batman supporting characters like Harley Quinn has their own show.