One idea could be that Hulk and Wonder Woman team up to fight a common enemy, like a powerful alien invasion. Their different powers would make for some exciting battle scenes. Hulk's brute strength combined with Wonder Woman's combat skills and magical weapons would be a great combo.
Maybe there's a story where Hulk accidentally finds himself in Wonder Woman's world. He's confused and a bit out of control at first, but Wonder Woman helps him understand and they form an unlikely friendship. They then work together to protect her world from threats that her usual allies can't handle on their own.
A plot could involve a powerful villain who has the ability to manipulate emotions. The villain targets Hulk and makes him go on a rampage in Wonder Woman's city. Wonder Woman has to figure out a way to stop Hulk without hurting him too much and then together they track down the villain and defeat it using their combined strength and intelligence.
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.
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.
One idea could be a misunderstanding. Maybe some false information makes Batman think Wonder Woman has been compromised and he has to stop her. Another could be a competition for a powerful, mysterious artifact that they both believe they should safeguard. And a third idea could be a mind - control situation where Wonder Woman is being controlled by an enemy and Batman has to fight her to break the control.
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.
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.
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 interesting plot idea could be that Hulk and She - Hulk have to team up to fight a new super - villain who is immune to their individual powers. They must learn to combine their strengths in a new way. Another could be a story where they accidentally swap powers and have to deal with the consequences. For example, She - Hulk might struggle with Hulk's lack of control at times, while Hulk has to adjust to She - Hulk's more refined fighting style.
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 a crossover with Superman. Imagine Wonder Woman and Superman teaming up to fight a powerful alien threat that neither could handle alone. Their different powers and personalities would create an interesting dynamic.
One idea could be to create an OC who is a young Amazon in training. She could struggle with mastering the traditional Amazonian skills and look up to Wonder Woman as a role model. This OC could have a unique weapon or power that sets her apart.