The plot might involve the Justice League members being in awe of the advanced technology in Batman Beyond's world. They could struggle to adapt to it at first. Then, they discover a conspiracy that endangers both their time and the future. Batman Beyond would lead them through the future Gotham, and together they'd combine their powers and skills to take on the bad guys. Like, Superman might be shocked by the new limits of his powers in this different future environment, and Batman Beyond would help him figure it out.
Well, it could be about the Justice League traveling to the future where Batman Beyond operates. Maybe they need his help to fight a new threat that has some connection to their past villains. For example, a villain from the Justice League's past could have somehow influenced events in the future and they need Batman Beyond's knowledge of the future tech and his unique fighting style to stop it.
In this fanfiction, perhaps there's a time - space rift that brings the Justice League to the Batman Beyond era. They initially have misunderstandings with Batman Beyond, thinking he's too different from the original Batman. But as they face an enemy that can manipulate time, they realize they have to work together. The Flash could be really excited about the new speed - related tech in the future, while Wonder Woman would be intrigued by the new social dynamics. And they all join forces to close the rift and save both times.
One possible plot could be that in the future setting of Batman Beyond, an old threat from the Justice League's past resurfaces. Terry McGinnis as Batman Beyond teams up with the original Justice League members who have come out of retirement. They have to combine their old - school heroics with Terry's high - tech gadgets to defeat the villain.
In this fanfiction, Batman might show off his detective skills to the Justice League. He could solve a mystery that the other members couldn't. For example, he might find out the true identity of a new supervillain faster than Superman or The Flash.
In a 'Batman meets Justice League' fanfiction, there could be an epic team - up against a powerful new villain. Maybe Batman's detective skills would be crucial in uncovering the villain's plan while the other Justice League members use their superpowers to fight on the front line.
One idea could be a time - traveling adventure. Batman Beyond gets sent back in time to the era of the original Justice League. He has to team up with them to stop a threat that was once thought defeated but has returned in a new form. The contrast between the high - tech world of Batman Beyond and the more classic superhero settings of the original Justice League would create interesting dynamics.
Batman Beyond would be the most interesting. He's a new take on the Batman concept with his high - tech suit and different personality compared to the original Batman. He has to prove himself to the Justice League and show that he's just as capable, if not more so, in his own time.
Well, perhaps the Batman sons are initially in a difficult situation and the Justice League comes to their aid. This could lead to a series of adventures where the sons prove their worth to the League. They might also bring a fresh perspective to the League's way of doing things.
A good main villain could be Brother Eye. It's a powerful and menacing artificial intelligence. In a crossover, it could have evolved in the future to be even more dangerous. It could pose a threat to both the future world of Batman Beyond and the past era of the Justice League, forcing them to team up to take it down.
Well, it could be about Batman initially being hesitant to fully join the Justice League. Maybe he has trust issues with some of the members at first. Then, he gradually starts to work with them on a big threat that requires all their skills combined, like an alien invasion or a powerful super - villain that's too much for any one hero to handle alone.
Well, it could be that Batman gets caught in a powerful explosion during a fight against a super - powered foe. His suit is damaged, and he suffers from severe burns and internal injuries. The Justice League is then faced with the challenge of getting him medical help while also preventing the villain from achieving their evil goals. They might have to split up, with some members protecting Batman and others going after the bad guy.
There's also 'The Dark Knight of the Future in the League'. This fanfiction focuses on Batman Beyond's unique perspective within the Justice League. It shows how his different set of skills, being more in tune with the future tech, can be both an asset and a source of conflict. It's not too long but packs a punch in terms of character development and action scenes.