One idea could be that the Godzilla sees the human child in a dangerous situation, like a collapsing building during a battle, and decides to protect the child. It could then form an unlikely bond with the child, who is not afraid but rather curious about the giant creature.
One idea could be that Godzilla, as a human, has to hide his true identity while trying to understand human emotions. He might struggle with the concept of love and friendship, which are very different from his previous existence.
One idea could be a human scientist who discovers a way to communicate with Mothra and tries to convince her to team up with Godzilla against a new common enemy, like an alien invasion. The scientist could be in a race against time as the world is being quickly overrun.
Perhaps Godzilla in human form falls in love with a human. But he is constantly worried about endangering the person he loves because of his true nature. He has to battle his own kind, who see his relationship with a human as a betrayal, while also trying to keep his human love interest safe from the chaos of the kaiju world.
One interesting concept could be the idea of humans taming Godzilla. Imagine a story where a group of scientists find a way to communicate with Godzilla and train it to protect the Earth from other threats instead of causing destruction. Another concept might be a human - Godzilla bond, like a friendship or partnership that defies the norms of their usual relationship in the movies.
A plot could involve a human child who has a special ability to communicate with all animals in Zootopia. The child is then recruited by the Zootopia police to help solve a mystery that involves a group of animals that seem to be acting strangely. This could lead to an adventure where the child discovers new aspects of the city and its inhabitants.
One idea could be a story where Little Godzilla teams up with other baby kaiju to protect their island home from human pollution. They use their small but growing powers to clean up the mess and teach humans a lesson about respecting nature.
One idea could be a Godzilla crossover with King Kong. They could start off as enemies but then have to team up to fight a common, greater threat like an alien invasion. This would bring in the classic monster -vs- monster dynamic at first and then shift to an alliance against a new foe.
One idea could be Godzilla emerging in the world of RWBY and the Huntsmen and Huntresses having to figure out how to deal with it. Maybe they initially mistake it for a new type of Grimm.
How about a Godzilla crossover with the Avengers? Maybe in a world where the Avengers exist alongside the Kaiju. Godzilla could be seen as both a threat and an ally. Iron Man could try to study Godzilla's power source while Thor might see him as a kind of primordial force. Captain America would be the one trying to keep everyone in line and figure out how to co - exist with this giant monster.
A great concept would be a fanfiction where Godzilla's transformation is linked to a human's emotions. For instance, when a particular human character experiences extreme love or rage, it triggers Godzilla's unexpected transformation. This could add a whole new layer of emotional depth to the story.