Frozen Hearts (Frozen fanfic/Rise of the Guardians fanfic)

Elsa of Arindelle was born with ice magic. Her whole life is spent trying to hide it, to protect those she loves. She spends most of her days alone in her room, fearing someone would discover her gift. When her parents are shipwrecked, Elsa becomes becomes queen. On top of the struggle of keeping her powers hidden, Elsa starts hearing a voice. Is she going mad?

During the party celebrating her coronation, her sister Anna argues with her to the point where Elsa loses control and reveals her gift. In devastation, Elsa flees. While she's alone on the mountainside, she hears the voice again, and finally discovers who it belongs to.