A major theme is the clash of cultures. Ben 10 comes from a more science - fictiony world with his alien forms and gadgets, while the Avengers are from a more traditional superhero world. Fanfictions often explore how these two different worlds' values and ways of doing things interact. For example, Ben might approach a problem in a more alien - like way that the Avengers have to adapt to. There's also the theme of acceptance, as the Avengers have to accept Ben as a valuable ally despite his different origin and powers.
In a Ben 10 Avengers crossover fanfiction, the story might involve Ben and the Avengers sharing their technology and knowledge. Maybe Iron Man could upgrade some of Ben's alien tech, while Ben could show the Avengers some unique alien abilities they've never seen before. It could also lead to some interesting character dynamics, like Spider - Man and Ben comparing their powers and how they use them to protect the city.
In some fanfictions, there might be a plot where the Avengers mistake Ben for a threat at first. But then they realize his good intentions when he helps them fight a common enemy. This adds an element of misunderstanding and then friendship, which is quite common and engaging in crossovers.
In some fanfictions, the technology in Ben 10's world might be combined with Stark's technology in the Avengers. Maybe Ben's Omnitrix could be enhanced by Stark's knowledge, creating a more powerful device that helps them in a battle against an alien invasion. This would involve a lot of scientific discussions and teamwork between Ben and the Avengers, especially Tony Stark.
Well, let's consider Ben's alien form that can absorb energy. When combined with Hulk's raw power, they could create a situation where the alien absorbs Hulk's excess energy during his rage - filled moments. This would not only prevent the Hulk from causing too much destruction but also use that absorbed energy to power up the alien form for a more powerful attack. And in the case of Black Widow, Ben could transform into an alien with enhanced agility and stealth, and together with her combat skills, they could infiltrate enemy bases more effectively.
A cool plot might be that a new villain emerges who has the power to steal the powers of superheroes. This villain targets both Ben's aliens and the Avengers. Ben and the Avengers have to work together to not only stop the villain from stealing more powers but also find a way to get their powers back. Ben's knowledge of his Omnitrix and the various alien weaknesses could be crucial in devising a plan, while the Avengers' combat experience and teamwork skills would be invaluable in facing the challenges along the way.
One great 'Ben 10 Avengers fanfiction' is 'Ben 10 in the Avengers World'. It shows Ben Tennyson teaming up with the Avengers to fight a powerful new enemy. The story does a great job of mixing the powers and personalities of both universes.
It could be about Ben 10 characters joining forces with the Avengers to fight a common enemy. For example, they might team up against a powerful alien or a super - villain who has the ability to cause chaos on a global scale. Ben's alien forms could bring unique powers to the alliance, while the Avengers' skills and teamwork would also play a crucial role.
One great idea could be Ben using his Omnitrix to transform into an alien that has a power similar to one of the Avengers. For example, turning into an alien with super strength like the Hulk and having a friendly competition with him. Another idea is that the Avengers could mistake Ben for a threat at first because of his alien forms and then they realize he's actually on their side. They could then team up to fight a common enemy, like a powerful villain from the Ben 10 universe that has somehow made its way into the Avengers' world.
I think Ben's Heatblast and Thor would be an interesting combination. Heatblast can generate intense heat and fire, while Thor has his lightning powers. They could create some really powerful elemental attacks together.