Thread:MrBlonde267/@comment-10674-20161105202642/@comment-265341-20161110041448

Yeah, Zero Hour basically wiped out everything involving Joe Chill. The Batman writers at the time decided that they didn't want the murderer of Batman's parents to be a specific person... the idea being that any criminal Batman deals with might actually be his parents' murderer. That was canon until Infinite Crisis in 2005, after which Grant Morrison's "Joe Chill in Hell" story brought Joe Chill back. Year Two really never gets referenced anywhere... all of the stuff with Batman teaming up with Joe Chill and using a gun and contemplating murder is just something people have decided to wipe from the Batman mythos.

I don't think Zero Hour was a hard reboot for Year Three, but Dark Victory definitely went on to become the new canon for Robin's origins with a very different take on Tony Zucco. It didn't explicitly change at Zero Hour, but that's the closet item in Retcon Roulette that would make sense.