In an episode of * MAS*H, * Frank Burns plots with Hawkeye and Hunnicutt to put Margaret in her place.
In a Three Stooges movie, the stooges get wise about two conmen posing as bobbies.
On * Leave It to Beaver, * Eddie Haskell helps Wally clean up a mess Beaver made–more than once.
In * It’s a Wonderful Life, * George Bailey very nearly changes character–right up to the time he begins a handshake with Potter.
Any other instances of temporary character change in movies, TV or literature? (And I don’t mean * Hamlet! )*
The starting point of BATMAN BEYOND is that Bruce Wayne, having lost a step but still doing his best to fight crime and save lives, makes a pretty good entrance while swiftly disarming the crooks du jour, but now he’s taking a beating, and taking a beating, and desperately reaching for whatever’s at hand to even the odds, which – oh, snap, did he just pull a gun on those youths? Yeah, no; he’s not going to keep fighting until he someday goes down swinging; he’s going to quit right now, before he kills somebody.
I’d exempt comic book characters from this since series get rebooted, reimagined, and downright f’ed up so often. Any (comic book) series that’s been popular for more than a decade has gotten redone at least once (usually when starting in a new format, like going from print to live action or animation).