I'm not sure if there is an existing 'jack frost x elsa pregnant fanfic' specifically. There are a vast number of fanfics out there in the fandom world, and it might exist, but it's not something that I can confirm with certainty. You could try searching on some major fanfic websites to see if you can find one.
There are indeed. A lot of these fanfictions explore unique storylines. For example, they might be brought together by a common threat to their wintry worlds. In these stories, the writers often play with their different personalities. Elsa's more reserved and self - discovery - focused nature against Jack Frost's more carefree and mischievous personality makes for an interesting dynamic.
Another theme is the discovery of new worlds. Jack is from his own realm, and Elsa and Anna are from Arendelle. In many fanfics, they explore each other's worlds. This can involve Jack showing Elsa and Anna his magical winter world, or Elsa and Anna introducing Jack to the wonders of Arendelle, like the coronation traditions or the trolls' magic.
In this fanfiction, Marshmallow could be a significant character. He's a large and somewhat intimidating snow creature created by Elsa. But with the baby on the way, he could become a gentle protector. He could stand guard outside their home to keep any potential threats away. Also, the trolls from the Frozen universe could play a role. They are wise and could offer their knowledge on how to take care of a baby with magical powers. They might even perform a special ceremony for the unborn baby.
They can develop their relationship through their shared care for the baby. For example, when the baby is sick, Elsa uses her powers to keep it cool while Jack tries to cheer it up. This mutual effort in taking care of the baby can bring them closer.
It would likely be a very imaginative story. It might start with Jack Frost and Elsa meeting in some sort of magical cross - over event. Their relationship could develop over time, leading to the pregnancy. There would probably be a lot of focus on how they deal with this unexpected situation, considering their different natures and powers.
Love across different realms is also a major theme. Jack Frost comes from a different mythological or magical background compared to Elsa from Arendelle. Their marriage in fanfiction represents the idea that love can transcend these differences. Fanfictions often explore how they bridge the gap between their two worlds, whether it's through sharing their magic or learning about each other's cultures and ways of life. This can involve things like Jack introducing Elsa to the more wild and untamed aspects of winter magic, while Elsa shows Jack the more structured and civilized side of Arendelle.
They could participate in a school talent show. Jack might show off his amazing ice sculptures he can create with his hands, while Elsa uses her powers to create a beautiful ice rink on stage. The audience is in awe, and after the show, they share a special moment backstage, realizing they are each other's biggest fans.
In Jack and Elsa meet fanfiction, the authors usually explore the characters' personalities. Jack is often portrayed as a free - spirited and mischievous character, while Elsa is more reserved due to her past traumas. When they meet, they can learn from each other's experiences and grow. For example, Jack could teach Elsa to be more carefree, and Elsa could show Jack how to handle his powers more responsibly in some cases.