One idea could be a story where Batman and Superman's kids team up to solve a mystery in Gotham City. Maybe they find a strange device that's causing chaos and they have to use their combined skills, like Batman's detective skills and Superman's super strength, to figure it out.
First, you should decide on the main characters. Are they the actual kids of Batman and Superman, or are they young sidekicks? Then, think about the setting. It could be in Metropolis, Gotham, or a new fictional city. For example, if you choose Gotham, you can describe the dark alleys and tall buildings.
One possible reason could be mind control. Maybe some villain has taken over Superman's mind and made him do it. Another reason might be a fundamental difference in their ideologies that has escalated to the point of no return.
Lois Lane is often a popular character. In fanfiction, she might play a crucial role in mediating between Batman and Superman or getting involved in their adventures in a more hands - on way, using her investigative journalism skills.
Alfred Pennyworth is quite popular too. He can offer his wisdom and support to Batman, and his interactions with Superman can be both humorous and heartwarming. He's like the glue that holds things together in the Batcave, and his presence can bring a sense of home to the story.
In Batman and Superman fanfiction, 'stranger danger' can be depicted in various ways. For example, a new villain could be introduced who is a stranger to the city and poses a great danger. The heroes would then have to figure out the stranger's motives and powers to stop them. It adds an element of mystery and suspense to the story.
It could be that in the fanfiction, Superman has been corrupted in some way. His values have shifted, and he sees Batman as a threat to his new - found ideology. So, he decides to take Batman down, resulting in the injury. This could lead to a complex story of redemption or further conflict.
The friendship in fanfiction often shows how they overcome their differences. Superman, the idealist, and Batman, the pragmatist, learn from each other. They might start as rivals but gradually realize that together they can achieve more. Fanfictions can also explore their personal lives outside of heroics and how their friendship impacts those aspects.
In fanfiction, Batman and Superman's friendship is often complex. They are two very different heroes. Batman is a brooding, human with no superpowers but great intellect and skills. Superman is an alien with god - like powers. Their friendship can be based on mutual respect for their fight against evil. Sometimes Batman is the one to keep Superman grounded, reminding him of his humanity. And Superman, in turn, can show Batman that there is more to the world than just the dark alleys of Gotham.
Pink kryptonite in fanfiction related to Superman and Batman can add a touch of the unexpected. It's not a traditional element from the main DC canon. Fanfic writers might use it to make Superman more vulnerable in a different sense than the usual kryptonite. And Batman, being the strategist, could use this situation to his advantage in the story, perhaps to gain some upper hand in their often - complex relationship.