Fan Casting The Flash/Barry Allen in Batman 2: City Of Owls

So understandable that there'd be confusion at this point, however thinking about doing a flash movie in-between JL 2 and 3 as well where he stumbles upon the time travel ability and tries to learn it. Have also thought about "someone" leaving a Legion flight ring with a time travel modification added, left on Barry's desk with a note saying "Fate is a fickle thing"