It's possible that his powers would be more erratic. As a baby, he doesn't have the control he has as an adult. So, his ice - making abilities might go off randomly. For example, he could accidentally freeze the water in a nearby pond just by being near it while having a little tantrum. But as he grows and learns about his powers again, he would start to gain more control over them.
Well, one possibility is that he could be taken in by a kind family. They might not know who he really is and just think he's an ordinary baby. They would care for him, feed him warm milk, and keep him cozy in a little crib. As he grows up, he might start to show signs of his magical powers, like making little ice crystals form on his crib railing when he's excited or sad.
His powers would likely be severely limited. The Sharingan, which requires a certain level of mental focus and chakra control, would probably not work as effectively. As a baby, Sasuke's chakra system is not fully developed, so he might not be able to access the full potential of his powers. He might only be able to use the Sharingan in short bursts, like when he's really scared or in immediate danger.
His powers might be affected in different ways. For example, his web - shooting ability could be less precise. Since he's a baby, he doesn't have the same muscle control and coordination as his adult self. So, the webs might come out in a more random direction.
One idea could be that Jack Frost turns into a human to experience the warmth of human emotions. He might find himself in a small town during winter. As a human, he discovers the joy of a hot drink on a cold day, something he never truly understood as a spirit. He could also fall in love with a local girl who is kind - hearted and loves the winter. This newfound love makes him question whether he wants to return to his former state or stay human forever.
Elsa's powers are often associated with her emotions and her need to protect her kingdom. Jack's powers are more about bringing joy and a sense of wonder. In the baby's upbringing, Elsa's influence could make the baby more aware of the consequences of its powers and how to use them to safeguard its home. Jack's influence would be more about exploration and using the powers to make others happy. The baby might grow up learning from Elsa how to contain its powers when it's angry or scared, and from Jack how to spread joy during the cold winter months. It could also have a bit of a struggle as it tries to please both parents, but ultimately it would find its own way to combine their teachings and use its powers in a way that is true to itself.
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.
I think Naruto would be one of the most affected. Since he and Hinata have a special connection, having her turn into a baby would completely change their dynamic. He'd have to step up and be responsible in a new way.
Lucy would be very affected. She's one of Natsu's closest friends. She'd have to take on a lot of responsibility for taking care of baby Natsu, which would disrupt her normal life of doing quests and writing her novel.
Perhaps in this form, Jack Frost is befriended by a young human child. The child doesn't realize he's Jack Frost and just thinks he's a really cool and strange little animal. They go on adventures together in the winter wonderland, with Jack Frost using his powers in small, unnoticeable ways at first.
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.