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.
Well, it could be a story about how they adjust to their new life as parents. Maybe they face challenges like sleepless nights with the baby, but also experience great joy in watching their child grow.
One popular type is where they go on adventures as a family with their baby. For example, they might take a trip to the Enchanted Forest and teach their baby about the magic there.
Kristoff might become more tender and patient. Before having a baby, he was a bit rough around the edges, but with a new - born in the house, he has to learn to be gentle. For example, he could be seen singing lullabies in his own gruff voice. Anna, she could develop a stronger sense of responsibility. She was always brave, but now she has to be brave for the baby too. So she might be more assertive in protecting her family.
One possible plot could be the challenges they face as new parents. Maybe Kristoff is worried about providing for the family while still being part of the ice - trading business. Anna, on the other hand, might be struggling with the balance between her royal duties and taking care of the baby. They could also have an adventure where they have to protect their baby from some sort of threat in the magical world they live in.
Some Disney - themed fan communities on social media platforms might also recommend or even host their own Kristoff and Anna baby fanfiction. For example, on Tumblr, there could be groups dedicated to Disney fan creations, and within those, you may discover some really interesting takes on the idea of Kristoff and Anna having a baby.
One possible plot could be that they face challenges in adjusting to their new life as parents. Maybe they struggle with sleepless nights and learning how to take care of the baby. Kristoff might use his skills from living in the mountains to build a special crib or play area for the baby. Anna, on the other hand, would be the loving and nurturing mother, singing lullabies she learned from the castle.
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.
You can try fanfiction websites like Archive of Our Own. There are often many different fanfictions about various characters and scenarios from Frozen, including those about Anna, Kristoff and their baby.