The characters would likely start off a bit cautious. Ben might be in awe of the Avengers' fame and power. The Avengers would be curious about Ben's alien - changing abilities. They'd probably exchange stories about their battles at first.
In a Ben Ten and Avengers fanfic, the interaction would be complex. Ben, being a young hero, would look up to the Avengers as role models. He would be eager to prove himself. The Avengers, initially, might see Ben as a bit of an unknown factor. However, as they work together, there would be a lot of exchange. Ben could use his alien forms to complement the Avengers' abilities. For example, using Upgrade to enhance some of their weapons. The Avengers would, in turn, offer Ben protection and guidance. They might teach him how to better handle the media and public relations, which is something Ben isn't used to. Also, characters like Hulk and some of Ben's more powerful alien forms would have an interesting dynamic, with both being forces of great strength but with different levels of control.
Ben would probably be in awe of the Avengers at first. He might try to show off his alien forms to impress them. The Avengers, on the other hand, would be cautious. Tony Stark might want to study Ben's Omnitrix. Thor could be interested in the power of Ben's alien forms that are related to strength and lightning.
Well, Ben, being a young and adventurous hero, would probably be in awe of the more established X - Men at first. He might try to show off his alien forms to them. The X - Men, on the other hand, would be cautious. For example, Storm might be intrigued by Ben's ability to change forms but also concerned about the potential chaos it could bring. Wolverine would likely be a bit gruff with Ben, but also respect his fighting spirit. And Ben's cousin Gwen could bond with Jean Grey over their psychic and magic - like powers.
The Avengers might be initially cautious around the cast, not fully understanding who they are. The actors, on the other hand, would probably be star - struck. For example, Robert Downey Jr.'s character in real life might try to crack jokes with Iron Man. And Thor might be a bit confused by the concept of actors playing him.
The characters would have a very interesting interaction. For instance, Thor might be intrigued by Aquaman's trident as it has a similar kind of power to his hammer. They could compare their weapons and the magic or technology behind them. Iron Man would probably be fascinated by the technology in Atlantis and might try to adapt some of it for his suits. And Aquaman would have to adjust to the Avengers' more brash and direct approach compared to the more reserved ways in Atlantis. He might initially clash with Hulk due to Hulk's uncontrollable nature, but later find a way to work together, like using Hulk's strength to move large underwater structures.
The characters would likely start off with some level of mistrust. For instance, the Avengers might be suspicious of Build's powers and his motives at first. However, as they face threats together, they would start to respect each other. Iron Man and Build could bond over their love for technology and inventing new gadgets. Captain America might be initially skeptical but would come to admire Build's courage in battle.
They might start off a bit warily. The Howling Commandos could be skeptical of the Avengers' powers at first. But then they would realize that they can all contribute to a common goal. For instance, Thor's lightning could be used in a way that the Commandos had never seen before, and they could offer their knowledge of stealth and guerrilla warfare to the Avengers.
Ben might initially be very cautious around the Xenomorphs. He's used to his own set of aliens, but these are something entirely different. He could try to communicate with them using his alien forms' unique abilities, but it might not work as the Xenomorphs are more about instinct. The Xenomorphs, on the other hand, would probably see Ben as a threat or a potential host.
He could be a great addition for his brute strength. Just imagine him in a battle against a powerful enemy like Thanos. He could hold his own and even distract Thanos long enough for the other Avengers to come up with a strategy.
The interactions would be diverse. Batman from Young Justice's world might have a serious conversation with Captain America about leadership. They both lead their respective teams. Artemis could befriend Black Widow and learn some new combat skills from her.
The characters' interactions would be complex. Hulk might just charge at Kratos out of instinct, seeing him as a potential challenger. Kratos, on the other hand, might hold back at first, trying to gauge the Hulk's power. Iron Man would likely try to scan Kratos to understand his abilities. Thor could start a conversation about their different pantheons.