The combination of powers. You get to see the superpowers of the X - Men, like Jean Grey's telekinesis and Cyclops' optic blasts, interact with the powers of the Avengers such as Thor's lightning and Captain America's super - strength. It makes for some really epic battle scenes.
One great 'xmen and avengers crossover fanfic' is 'The United Front'. It has an exciting plot where the X - Men and the Avengers have to team up against a common enemy from another dimension. The character interactions are really well - written, especially the banter between Wolverine and Iron Man.
There's a fanfic called 'X - Avenger Team - Up'. It's a shorter but very engaging read. It focuses on a specific mission where a small group of X - Men and Avengers have to work together. The dialogue in it is really well - written, making the characters feel very true to their original versions. It shows how their different personalities can either clash or complement each other during the mission.
Another plot could involve a misunderstanding between the two groups. Maybe some of the Avengers misunderstand the X - Men's mutant powers as a threat and start a conflict. But then they realize they were wrong and join forces to face a real villain who was secretly manipulating the situation. This would involve a lot of character development and relationship building among the different heroes.
The popularity of 'Xmen X Avengers Fanfic' lies in the combination of two very popular superhero groups. Fans love to see how the mutants from X - Men and the heroes of Avengers interact. For example, seeing Storm and Thor use their powers side by side is really exciting. It also allows for new storylines that the official comics or movies might not explore.
Storm and Thor could make a powerful duo. Both have control over powerful natural forces, Storm with the weather and Thor with lightning and thunder. Their powers could be combined in unique ways to take on powerful enemies. Also, they could have an interesting cultural exchange as Storm is from Africa and Thor is from Asgard.
One common theme is the exploration of power dynamics. When the X - Men cross over with other groups, like the Avengers or the Fantastic Four, there's always a comparison and contrast of their powers. For example, in a crossover with the Avengers, the mutants' powers might be seen as more unpredictable compared to the technology - based powers of some Avengers.
Maybe in the fanfic, Batman's rogues gallery somehow teams up with some of the Avengers' villains. This forces Batman and the Avengers to work together. Batman could introduce his unique gadgets and combat style to the Avengers, while they could show him their superpowers up close. For example, Iron Man could be intrigued by Batman's utility belt and try to create his own version of some of the gadgets.
A good plot could involve a villain from the Homestuck universe creating chaos in the Avengers' world. The Homestuck characters come to help, but there are misunderstandings at first between them and the Avengers. However, as they start to understand each other's powers and motives, they form a strong alliance to defeat the villain.
There's also 'X - Men and the Fantastic Four: A Mutant Alliance'. In this fanfiction, the X - Men team up with the Fantastic Four. It delves into how the two groups, with their different powers and personalities, work together. There are some really fun moments as they try to figure out how to combine their abilities to face various threats.