A fanfic could explore a scenario where Batman is framed for a crime on Themyscira. Wonder Woman doesn't believe he's guilty and they have to work together to clear his name while also uncovering a conspiracy within her own homeland that threatens both their worlds.
Maybe in the fanfic, there is a threat to the entire world that only the combination of Wonder Woman's Amazonian knowledge and Batman's technological resources can solve. For example, an ancient artifact has been stolen and is being misused. They start off not trusting each other fully but as they work together, they develop a deep respect.
A great plot for this fanfic could be that a mysterious force is causing chaos in both Gotham and Themyscira. Batman and Wonder Woman join forces to investigate. Along the way, they discover that the source of the problem is related to an old grudge between two long - forgotten groups. As they dig deeper, they also explore their own feelings for each other and how their different approaches to justice can be reconciled.
Perhaps Batman discovers a strange artifact that has ties to Wonder Woman's homeland. He seeks her out for help in understanding it, and together they uncover a plot by an ancient evil force that was once sealed away but is now trying to return. Their journey involves not only fighting off minions of this evil but also learning about each other's worlds more deeply.
One plot idea could be that an otherworldly threat emerges that only their combined powers can stop. They have to put aside their differences and work together seamlessly. For example, a powerful alien race plans to invade Earth and they need to use Batman's strategic mind, Superman's super strength and Wonder Woman's combat skills.
One idea could be that Static's electrical powers interact in unexpected ways with Wonder Woman's magic lasso. Maybe when he accidentally touches it, it creates a power surge that sends them both to an alternate dimension where they have to work together to get back.
One idea could be that Batman and Wonder Woman have a major disagreement over how to deal with the Injustice regime. Batman wants to use more stealth and subterfuge while Wonder Woman believes in a more direct approach. This could lead to some intense battles between them, not physical but more of a battle of wits and ideologies.
One idea could be that Batman and Wonder Woman are both vying for the attention of a new superhero in town. Batman is jealous because Wonder Woman seems to have a natural connection with this new hero, perhaps due to their similar powers or backgrounds. Wonder Woman, on the other hand, is jealous of Batman's detective skills which the new hero seems to admire a great deal. This could lead to a series of challenges and competitions between Batman and Wonder Woman to prove who is more worthy of the new hero's friendship or alliance.
A possible plot could involve a mind - control situation. An evil sorcerer manages to put Robin under his spell and sends him to attack Batman and Wonder Woman. They are reluctant to fight Robin but have to find a way to break the spell without harming him. Meanwhile, they also need to stop the sorcerer from using Robin to carry out more devious plans, like stealing secrets from the Justice League.
One idea could be that a powerful new villain emerges who is a threat to both Gotham and Themyscira. Batman and Wonder Woman team up to track down the villain's lair. Batman uses his detective skills to analyze the clues while Wonder Woman uses her combat skills in the battles along the way.
One idea could be that Batman and Wonder Woman team up to face a new threat that combines high - tech weaponry and ancient magic. Maybe a villain has found a way to use old Amazonian spells with modern technology to create chaos in Gotham and Themyscira. Another plot could involve a love triangle where a new character is introduced and both Batman and Wonder Woman have complex feelings towards this person, which challenges their friendship and working relationship. A third idea is that they discover a hidden connection between their families' pasts that has been long forgotten, and this discovery changes how they view each other and their respective missions.