It could be amazing. Picture Superman and Thor having a friendly strength competition. Maybe Batman and Iron Man would be sizing each other up, with Batman being impressed by Iron Man's high - tech gadgets but also showing off his own detective skills. Wonder Woman and Captain Marvel could team up to take on some powerful villains. The different powers and personalities from both teams would create a really interesting dynamic.
One possibility in this fanfiction is the cultural clash. The Avengers are more of an American - based team, while the Justice League has a more global feel. This could lead to some interesting interactions. Hulk might get frustrated with Aquaman at first because he doesn't understand the underwater world. But as they learn about each other, they could form an unexpected bond. Also, the magic users like Doctor Strange and Zatanna could exchange knowledge, creating new spells or ways to fight off enemies.
Maybe a villain from the Justice League's rogues gallery teams up with an Avengers foe. Let's say Lex Luthor and Doctor Doom. They create a device that can swap powers between heroes from both teams. This leads to some really fun and chaotic situations. For instance, Captain America with the Flash's speed or Wonder Woman with the Hulk's strength. The two teams have to figure out how to work with their new, swapped powers and stop the villains.
One exciting plot could be that Thanos teams up with Darkseid. The Avengers and Justice League initially misunderstand each other's motives while trying to stop this powerful alliance. They end up in battles among themselves until they realize they need to work together. Iron Man and Batman could be the first to figure it out, using their intellects to analyze the situation.
In a Justice League Avengers crossover fanfic, there could be epic battles. For example, Superman and Thor might have a showdown to test their super strength. They could exchange powerful blows while the other heroes watch in awe.
Well, a cool plot could be that some sort of cosmic event has merged their universes in a strange way. Members of the Avengers start showing up in the Justice League's world and vice versa. Iron Man could team up with Batman to figure out how to reverse the situation while Thor and Superman have an epic showdown that ends in mutual respect. And then they all work together to fix the messed - up universes.
Captain America and Wonder Woman could potentially be rivals. Captain America has his strong sense of patriotism and old - fashioned values from the 1940s, while Wonder Woman comes from an ancient, mythical island with her own set of values. They might clash over different ideas of leadership and how to handle certain situations, like when to use force or diplomacy.
One idea could be that a powerful cosmic threat emerges that neither the Justice League nor the Avengers can handle alone. So they have to combine their forces. For example, Superman and Thor could team up to take on a super - strong enemy, using their strength and lightning powers respectively. Batman and Iron Man might start off butting heads as they both think they have the best strategies, but eventually work together to outwit the villain's high - tech defenses.
Wonder Woman and Thor would be an exciting pair. Both are powerful warriors from myth - inspired backgrounds. They could exchange stories about their gods and goddesses. In battle, they could combine their strength and weaponry. Wonder Woman's lasso and Thor's hammer could be used in creative ways to defeat enemies. Their personalities are also quite bold, so there would be a lot of banter and mutual respect between them.
In my opinion, it could be Scarlet Witch. Her reality - warping powers are extremely potent. In a crossover, she could potentially change the very fabric of the combined universes. If she were to go rogue or be influenced by an evil force, she could cause chaos on a scale that would be very difficult for the combined might of the Justice League and the Avengers to handle. Even Superman's invulnerability might not protect him from her reality - warping abilities. She could simply make him mortal or take away his powers altogether.