There probably is. The Frozen fandom is quite large and diverse, so it's not surprising that there could be a fanfiction where Kristoff and Anna are pregnant. It could be an interesting read as it might explore how their relationship evolves with the new addition to their family on the way. Maybe it would also show how their friends in Arendelle react to the news.
One possible plot could be that Anna discovers she's pregnant and she and Kristoff are overjoyed. But then they face challenges like how to keep Anna safe during her pregnancy in the sometimes - dangerous world of Arendelle. They might also worry about how to raise the child with all the responsibilities of ruling the kingdom.
One possibility in fanfiction is that they start a family right away. Kristoff would be a loving and protective father, teaching their children about the ways of the forest and ice. Anna would pass on her knowledge of the kingdom and how to rule with kindness. Their home would be a place full of love and laughter, with Sven often coming around to visit.
One idea could be that their baby has a special power related to ice like Anna and Elsa. Maybe the baby can create beautiful ice sculptures at a very young age. This would add a new element to the Frozen world and also show how the family's powers are passed down.
One possible antagonist could be a power - hungry wizard who wants to take over the kingdom of Arendelle. He sees Anna and Kristoff as threats to his plans and tries to stop them from protecting the kingdom. He uses dark magic to create various obstacles for them.
One popular scenario could be after they've defeated some great danger together. For example, after facing a new threat to Arendelle, they realize how much they mean to each other and share a passionate kiss. The setting might be in the middle of a snow - covered field, with the moon shining bright above them.
One plot idea could be that Anna and Kristoff get lost in a magical forest on their way back from a diplomatic mission. They have to rely on each other and their skills to find their way out while also facing strange creatures. Another could be a story where they have an argument over how to handle Elsa's new ice - related discovery, and it tests their relationship. Maybe a third idea is that Kristoff discovers a long - lost relative who doesn't approve of his relationship with Anna, and they have to work through that together.
Well, one thing that could happen is a grand celebration in Arendelle. All the people would come out to see their beloved princess Anna marry Kristoff. There would be ice sculptures everywhere as a nod to Elsa's powers, and the fjords would be filled with the sounds of music and laughter. The ceremony could be held in the castle courtyard, with Elsa using her magic to create a beautiful ice arch for them to stand under as they exchange vows.
One possible scenario could be that they share a kiss after a dangerous adventure. Maybe they were facing a powerful snow monster and Kristoff saved Anna. In the heat of the moment, filled with relief and newfound admiration, they kiss. Another could be during a celebration in Arendelle. After a successful harvest or a new alliance, the joy in the air leads to a spontaneous kiss between them.
One great fanfiction could be where Anna and Kristoff's baby has a special connection to the magic of Arendelle. Maybe the baby can communicate with the spirits of the forest like Elsa. Another story might focus on the challenges of raising a baby in a kingdom with so much history and responsibility.