Truly iconic fictional characters stand the test of time, rarely change much from one generation to the next, and will go on to outlive us all.
Take Superman for example. He's been around since the '30s and always been the epitome of clean-cut good guy, a quality that's celebrated among his undying fanbase.
The many who cherish the character have a fixed idea about how he should be portrayed and changing that takes some doing, but it is possible.
A prequel or sequel which expands on pop culture mythology in meaningful ways while staying true to everything the property stands for usually does it. If a movie can pull this off, the fans will add what it's peddling to their perception of said characters.
Some films, however, change the way people see famous characters in a less than positive way: from the ill-advised reboots which reinvent them as something horrible, to the unnecessary sequels that tarnish legacies. Indiana Jones, for instance, had his reputation crushed beneath a nuke-proof fridge.
These trends are set to continue, as there are a number of movies in the pipeline which are bound to alter the way the audience views some of the medium's most famous heroes and villains, for good and for evil.