So like last week i saw a post about an AU where Bruce dies and dad becomes Batman and the mom goes crazy and becomes the Joker.
The new DC movie Justice League The Flas Point Paradox has exactly that.
Flash messes up the time stream and that is an event that happens. The Batman through the entire movie is his father not him. They even have a little clip of it happening.
I told my parents about it before we watched the move and when it happend they just both looked at me like WTF.