One idea could be a story where Godzilla teams up with other kaiju from different universes to fight a new, super - powerful alien threat. This would bring in a whole new level of epic battles and interactions between the various monsters.
One idea could be to write a story from the perspective of a civilian caught in the middle of the Kaiju battles. Show their fear, their attempts to survive, and how they interact with the military trying to stop the Kaiju. Another could be a story about a Kaiju that has unique abilities not seen in the original lore, and how it changes the dynamic of the wars. Maybe it could be a Kaiju that can communicate with humans and tries to form an alliance against the more destructive Kaiju.
One idea could be a story where Mechagodzilla is initially built to protect the city from Godzilla, but then they discover a common enemy that forces them to team up. Maybe an alien force arrives that threatens both of them and the planet. So they have to put aside their differences and fight together.
One idea could be a story where Godzilla teams up with other kaiju to fight a new, more powerful alien threat. This would be exciting as it shows Godzilla in a more collaborative role.
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 that Godzilla and Kong team up against a new, even more powerful alien monster. This would force them to put aside their differences and combine their strengths. For example, Godzilla could use his atomic breath while Kong uses his agility and strength to climb on the new monster and attack its weak points.
A possible plot idea is that Godzilla is drawn to the Geo - Front in Evangelion. The reason could be the powerful energy sources there. The NERV organization is then forced to either work with Godzilla or find a way to get rid of it. They might study Godzilla's biology to see if they can use any of its abilities to enhance the Evas. Another plot could be that an Angel takes on the form of Godzilla to deceive the Eva pilots. This would make the pilots question their usual tactics when facing an 'Angel' as Godzilla has different strengths and weaknesses compared to the normal Angels. Also, a plot where Godzilla's presence causes a shift in the power dynamics between the different factions in Evangelion, like SEELE and NERV, could be really interesting.
A fanfiction could be about a new character who has the ability to see Death itself coming. This character tries to interfere with Death's plans for the Final Destination survivors, leading to a whole new set of challenges and twists.
One idea could be exploring the backstories of the minor characters in more depth. For example, the story of the civilians in Cocoon who were affected by the events. Another could be a what - if scenario, like what if Lightning had made different choices at certain key moments. And a third could be focusing on the relationship between Fang and Vanille before they became l'Cie.
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.
One plot idea could be that the sofa has some magical powers and it tries to communicate with Godzilla. Maybe it wants to convince Godzilla to stop causing destruction. Another could be that Godzilla accidentally sits on the sofa and it's a really comical situation as the sofa struggles under his weight.