A cool plot could be that an ancient prophecy involves both Arsenal and Wonder Girl. They initially don't believe it, but as strange events start to occur around them, they realize they might be part of something much bigger. They have to figure out what their roles are in the prophecy while also dealing with their own personal issues and the challenges of being young heroes in the Young Justice team.
One plot idea could be that Arsenal and Wonder Girl are on a mission together and get stranded in an alternate dimension. They have to rely on each other's skills to survive and find a way back home. Arsenal's marksmanship and Wonder Girl's super strength would be put to the test.
Maybe there's a plot where they have a misunderstanding at first. Robin thinks Wonder Girl is too reckless in battle, while Wonder Girl believes Robin is too controlling. But through a series of events, they come to understand and respect each other more, and in the end, they become a stronger team.
Another plot could be a time - travel adventure. Maybe a powerful magic spell goes wrong and sends them back in time. There, they meet younger versions of the Justice League members. They have to figure out how to get back to their own time while also making sure they don't accidentally change the future in a bad way. This would involve a lot of action and also some interesting character interactions as they see the heroes they know in a different light.
A plot could involve Arsenal getting injured during a mission, and Red Arrow has to take care of him. During this time, they have deep conversations about their lives as heroes, their families, and their place in the Young Justice team. It could lead to a stronger bond between them and a new understanding of each other.
Perhaps there's a fanfic where Robin and Girl Wonder accidentally swap their minds. This would lead to a lot of comical situations as they try to act like each other while also trying to figure out how to reverse the situation. But it could also have some deeper moments as they understand each other better through this strange experience.
One idea could be that Robin and Wonder Woman team up for a special mission in a hidden, ancient temple. They have to solve puzzles that require both Robin's detective skills and Wonder Woman's knowledge of ancient lore. Another could be a story where Robin gets injured during a battle and Wonder Woman takes it upon herself to train him in new combat techniques to make him stronger.
A possible fanfiction could focus on Wonder Girl's relationship with other members of Young Justice. For example, she might have a friendly rivalry with Superboy that turns into a strong bond as they face challenges together. This could include them training together and learning from each other's strengths and weaknesses.
It could start with mutual respect on the battlefield. As they fight side by side more often, they begin to trust each other. This trust could then turn into a friendship, and eventually, they might develop romantic feelings. For example, Arsenal might start to notice little things about Wonder Girl, like how she always encourages the team, and that could make him see her in a different light.
One idea could be that the Ghost Girl is actually a lost hero from another dimension. She has special powers that she doesn't fully understand and the Young Justice team has to help her control them while also trying to figure out how to send her back home. Another plot could involve the Ghost Girl being a spirit who is tied to a mystery that the team needs to solve. Maybe she was a victim of an old, forgotten experiment and her presence is a clue to stopping a new threat related to that experiment.
One idea could be that a new girl joins the team with a unique power. For example, she can manipulate time in small bursts. This causes chaos at first as the team tries to figure out how to use her power effectively. She might initially struggle to fit in with the group's dynamics, especially with the pre - existing relationships between the characters.
One idea could be a crossover where the Young Justice team has to team up with the Justice League to face an interdimensional threat. Maybe a powerful villain from another dimension is trying to invade Earth and the combined skills and powers of both groups are needed to stop it.