Who could be the main antagonist in 'Jack Frost Heart Gets Frozen' fanfiction?

In this fanfiction, perhaps Jack Frost's heart could be frozen due to a powerful dark magic spell. This might lead to him losing his ability to spread winter cheer and instead become a cold and distant figure.

It could be an ancient ice - hating wizard. This wizard might have been banished long ago but now that Jack Frost has gone back in time, he sees it as an opportunity to stop winter from ever existing. He could use his dark magic to melt all the ice and snow in the past, which would have a ripple effect on the future.

Pitch Black would be a likely main antagonist. He could manipulate Jack Frost into turning dark, as he has a history of preying on the insecurities of the Guardians.

Another option is that Pitch Black himself could be the main antagonist in a different way. He could start off as an anti - hero but then be corrupted by an even greater power of darkness. This new - found power makes him go overboard with his fear - spreading, and Jack Frost has to find a way to bring back the old Pitch Black or at least stop his rampage. This would create an interesting internal struggle within Pitch Black as well as an external conflict between him and Jack.

Another possibility is Gaara before he met Naruto. He had a really tough childhood and was initially very cold - hearted, seeing others as tools or threats. His heart was like a frozen desert, until Naruto's friendship started to thaw it. In this fanfiction, they could explore more of his pre - Naruto state of a frozen heart and how it affected his relationships with others in the shinobi world.

One possible plot could be that a magical anomaly causes the worlds of 'Frozen' and 'Rise of the Guardians' to merge. Elsa and Jack Frost meet and are initially suspicious of each other. But as they work together to figure out how to separate the worlds again, they start to develop feelings. Eventually, they share a kiss as a sign of their newfound love and as a way to use their combined ice powers to fix the anomaly.

A powerful ice - demon could be a great antagonist. It could be jealous of Jack Frost's power over winter and Danny's ghost powers, so it tries to take over their powers and rule both their worlds.

It could be Pitch Black. Since Danny, as Jack Frost, is new to the world of the Guardians, Pitch might see him as an easy target to disrupt the balance. He could try to turn Danny back into his Danny Phantom self or just use his in - between state to cause chaos among the winter spirits and the people of Amity Park.

Their interaction could be really magical. Elsa, with her ice powers, and Jack Frost, who is also associated with ice and winter, might start by being cautious around each other. Maybe they'd compare their powers, like how Elsa can create elaborate ice structures while Jack can make it snow and freeze things with a touch. They could also learn from each other. Elsa might teach Jack about controlling her kind of ice, which is more about building and creating, while Jack could show Elsa how to have more fun with ice, like skating on frozen ponds he creates just for that. It could be a really interesting exchange of skills and personalities.

Well, it could be a very magical moment. Elsa, with her ice powers, and Jack Frost, the spirit of winter, their first kiss might be surrounded by a flurry of snowflakes. Maybe they are in a secluded ice palace, and as their lips meet, the ice around them glows a soft blue. It's a moment that combines their powers and their new - found love, creating a beautiful and unique scene.