One idea could be a story about a human from the Ice Age who discovers a hidden cave filled with ancient markings that lead to a secret power. Another could be a love story between two humans from different tribes during the Ice Age. Or perhaps a story of a human's journey to find a rare herb that can cure a deadly disease spreading in his tribe.
Maybe the human baby is a special child with some kind of unique ability. In the Ice Age setting, this ability could be related to communicating with animals. So the baby uses this power to bring different animal species together to form an alliance against a common threat, like a large flood or a group of extremely aggressive and territorial creatures.
For the human baby, you can give it distinct features like a curious nature. Maybe it has big, bright eyes that seem to hold a lot of wonder. For the animal characters, like the sloth Sid, you could make them have their own quirks. For example, a woolly rhino could be really clumsy but with a heart of gold, always accidentally causing a bit of chaos but meaning well when it comes to protecting the baby.
As humans, Diego and Shira could have a more nuanced relationship. They might experience jealousy in a new way. Say, if another human showed interest in Shira, Diego would have to deal with his feelings in a different manner than he did as an animal. Also, they could express their love more openly, like through hugs and kisses, which are more typical human ways of showing affection.
One idea could be that Diego and Shira are transformed into humans by some magical force in the Ice Age world. They then have to learn how to live as humans while still retaining some of their animal instincts. For example, they might be really good at hunting in the wild as humans because of their past as saber - toothed tigers.
To make Ice Age human characters more believable, give them skills relevant to the time period. For example, they should be good at making fire, hunting, and building shelters. Also, their language should be simple and basic, as they didn't have complex grammar systems back then.
The appeal of Ice Age Shira fanfiction lies in the character herself. Shira is a complex character. She has a tough exterior from her pirate days but also a softer side. Fanfiction allows readers and writers to explore that duality more deeply.
A romantic relationship could be based on shared dreams. Maybe they both want to explore a new, uncharted area of their Ice Age world. They set out on an adventure together, facing the challenges of the cold and wild animals as a couple. Their love grows as they rely on each other for survival.
Some Pokemon might grow thicker fur or develop ice - like coverings. For instance, Eevee could evolve into a new form with white fur and ice crystals on its tail. Fire - type Pokemon might have a frosty sheen on their bodies as a sign of the cold affecting them. Water - type Pokemon could have icicles forming on their fins.
One interesting aspect of Ice Age Shira fanfiction could be exploring her backstory. Maybe she had a family before she joined the pirates. Writers could delve into how she became the fierce and independent saber - toothed cat we see in the movie. For example, perhaps she was separated from her family during a natural disaster in her early years, which made her tough and self - reliant.