It's hard to come to terms with the fact that Disney's 'Frozen' will be turning four years old this year. Topping 2013's highest-grossing movies ahead of Marvel juggernaut 'Iron Man 3', it's fair to say that the film had a huge cultural impact, and one whose ramifications can still be felt today.

Elsa was originally a pure evil villain in 'Frozen'Elsa was originally a pure evil villain in 'Frozen'

Telling the story of royal sisters Anna (voiced by Kristen Bell) and Elsa (voiced by Idina Menzel) - the latter of whom was cursed with icy powers - the tale is a heartwarming one that touches on many important and delicate topics, set against the gorgeous backdrop of the kingdom of Arendelle. Infusing music throughout, the movie is an uplifting and infectious affair.

As Elsa's 21st birthday looms ever closer, plans are put into action for her to become the queen of the land, but having kept her powers a secret, Elsa fears the worst; that her subjects will discover her magic and fear her. While in this final, canon version of the film, Elsa isn't inherently evil and is in fact doing her best to keep control of her powers and emotions, that wasn't always the way things were going to play out.

Anna wasn't always going to be of royal bloodAnna wasn't always going to be of royal blood

Speaking with Entertainment Weekly, 'Frozen' producer Peter Del Vecho explained: "When we started off, Anna and Elsa were not sisters. They weren't even royal. So Anna was not a princess. Elsa was a self-proclaimed Snow Queen, but she was a villain and pure evil - much more like the Hans Christian Andersen tale. We started out with an evil female villain and an innocent female heroine and the ending involved a big epic battle with snow monsters that Elsa had created as her army..."

Of course, when it comes to the final product, none of the original plans seemed to seep through. Del Vecho concluded that those behind the flick agreed they'd 'seen it before' and that there was a lack of an emotional connection with Elsa.

"We weren't drawn in," he said. "The characters weren't relatable." 

Because of that, everything was changed. Little did those involved know just how incredible the film would do because of those changes.

More: See The Trailer For The Non-Disney Version Of 'The Little Mermaid'

Walt Disney Animation Studios have confirmed work has started on a 'Frozen' sequel, but no details surrounding the plot or a release date have yet been revealed.