Yes, there are. For example, in some of the Justice League crossovers, they have significant interactions. These crossovers often show how they contribute to the team dynamic, with Wonder Woman being a powerful force and Batman being the brains behind many strategies.
One interesting story could be them teaming up to take on a powerful supervillain like Darkseid. Their combined skills, with Wonder Woman's strength and combat expertise and Batman's strategic mind and gadgets, would make for an epic battle.
You can find 'Batman x Wonder Woman Fanfiction' on popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of works in this category, with different takes on their relationship. There are also some on Fanfiction.net, although the quality can vary more there.
There's also 'Batman and Wonder Woman: The Unlikely Alliance'. This fanfiction takes a different route by starting with their initial distrust of each other. But as the story progresses, they discover they have more in common than they thought. It's full of action and has some great character development moments for both of them.
She could be devastated. Wonder Woman might go into a period of mourning, isolating herself from others as she grapples with the loss. She was used to having Batman as an ally, and his death would leave a big hole in her life.
In Batman and Wonder Woman fanfic, 'branches' could refer to different storylines or plot directions. For example, a fanfic might start with a common premise, like Batman and Wonder Woman teaming up to fight a new villain in Gotham. Then, one branch could be that they discover the villain has ties to an ancient Amazonian curse, leading them on a journey to Themyscira. Another branch might involve the villain being part of a secret society in Gotham, which Batman has to infiltrate with Wonder Woman's help.
At first, it might be a bit rocky. Batman is used to working alone and being in control, and Wonder Woman is a powerful and independent hero. But as they face challenges together, they would start to respect each other's abilities. They could develop a friendship based on mutual admiration for their different skills.
After the proposal, their relationship would likely become more public. They would no longer be just comrades in arms but an engaged couple. Their interactions would be more affectionate and they would start planning a future together.
Lex Luthor could be a great antagonist. He could be jealous of the new alliance between Wonder Woman and Batman and see them as a threat to his own plans for world domination. He might use his intellect and resources to try and turn the public against them or create some high - tech weapons to take them on.