Okay, so these two were technically "inspired" by Hans Christian Anderson's The Snow Queen. I'm bending the rules in this case, mostly because Disney does not so much "adapt" stories as "take inspiration from" them. The entire plot of this new age Disney musical hinges around the relationship between these two sisters, creating a universally heartwarming tale of sisterhood. The main strength of these two characters comes from how their stunted maturity (triggered by the death of their parents) incites, drives, and eventually resolves the whole plot of the film. Elsa, the snow Queen (voiced by Idina Menzel) is the undeniable focus of the film, but her internal struggles, beautifully rendered in song, would mean nothing without her sister Anna's (Kristin Bell) attempts to reach out to her. Anna has the first chance to charm the audience, but Elsa emerging from her shell is destined to become one of the great self-liberation anthems of our age. The fact that the central relationship to Frozen is not a romance only works to its credit. This relationship proves among the most interesting a Disney film has ever conjured up, because it requires more subtle attention to mannerisms, subtext, and character similarities to make work. Elsa and Anna are two of a kind, similar enough for their reconciliation to be possible, but different enough for it to be special.
Self-evidently a man who writes for the Internet, Robert also writes films, plays, teleplays, and short stories when he's not working on a movie set somewhere. He lives somewhere behind the Hollywood sign.