One possible aspect of the 'Jack Frost Dark Side' in fanfiction could be his struggle with his powers. He might be tempted to use them for self - gain or revenge. For example, in some fanfictions, he could be frustrated with how humans treat winter and decide to make it harsher than it should be, causing chaos and destruction.
Another theme is his isolation. As he delves into his dark side, he may push away those who care about him. This isolation can be both a cause and an effect of his darkening. He might feel that no one understands him and his internal struggles, so he further isolates himself, which only makes his dark side stronger.
Obviously, Jack Frost is the main character as the story is about his transformation into a dark version of himself. But there could also be other characters from the original Jack Frost lore, such as the Guardians like North, Bunny, and Tooth. They would likely play important roles, either trying to save Jack from his dark path or being forced to oppose him if he becomes too dangerous.
One common theme is friendship. Despite their differences, they often come to trust and rely on each other. Another is power. How their unique powers interact and complement each other is often explored.
Another plot could involve Jack Frost being lured into the darkness by an external force, like a shadowy entity. This entity might promise him more power and control over his existence. As he succumbs to it, his appearance could change, his eyes turning a deep, cold black, and his ice becoming darker and more dangerous. His personality would shift from the carefree spirit we know to a brooding and vengeful being.
One possible plot could be that Jack Frost is corrupted by a dark force. He starts to spread winter not as a fun, playful season but as a harsh, unforgiving one. He might turn against the other Guardians, believing they are holding him back from his true power.
One great 'Dark Jack Frost' fanfiction could be 'The Darkening of Jack' which explores a more menacing side of his character. It has an interesting plot where Jack Frost is influenced by a dark force and his actions start to have unforeseen consequences in the magical world.
One 'dark Jack Frost' story could be that Jack Frost, instead of just playfully frosting windows, freezes the entire town. People are trapped in their homes, unable to move due to the extreme cold he has brought. His frosty touch turns everything into ice sculptures of their worst fears.
Another theme is the power of nature gone awry. Jack Frost, who is usually a part of nature's cycle, becomes a force of destruction in these dark stories. He might overstep his normal role and bring excessive ice and snow, causing chaos. For instance, he could freeze rivers and lakes so solid that the fish die and the water supply for villages is cut off, disrupting the balance of nature.
One plot idea could be that Jack Frost is drawn to Elsa's ice powers. He visits Arendelle out of curiosity. They could start by being a bit wary of each other but then realize they can learn a great deal from one another about controlling and using their powers in new ways. For example, Jack might show Elsa how to have more fun with her ice, like creating ice sculptures that can move on their own.