In a fanfiction, their interaction could be complex. At first, the Avengers might be in awe of Superman. But then, some like Tony Stark might be a bit jealous of Superman's natural powers compared to his own tech - based ones. Superman, on the other hand, would be curious about the Avengers' teamwork. He might learn from them how to better coordinate with others in a fight. Black Widow could try to recruit Superman into the Avengers, but he might be hesitant as he has his own responsibilities in Metropolis. Eventually, they could work together on a mission to save the world from an alien invasion.
They might start by comparing powers. Superman's super strength and flight would be quite a topic. Thor would likely want to have a friendly competition with Superman in terms of strength. Then they could move on to sharing their experiences. Captain America could talk about his battles during World War II, and Superman could share his adventures in saving Metropolis. They could also team up to fight a new, powerful villain that neither could defeat alone. For example, a villain with the ability to nullify Superman's powers and hack into the Avengers' technology.
Superman would probably be polite but a bit reserved when meeting the Avengers. He'd introduce himself simply and state his purpose, which is usually to help. Iron Man, on the other hand, might be a bit skeptical at first and make some snarky remarks. Thor would likely be more open - minded and see Superman as a worthy ally. Hulk might just be interested in seeing if he can take on Superman in a fight.
Superman would likely be very respectful of the Avengers. He'd be curious about their powers and how they operate as a team. Iron Man, on the other hand, might be a bit wary at first, trying to analyze Superman's powers and find any weaknesses. Captain America would probably admire Superman's strong moral compass and see him as an ally right away. Thor might be interested in testing his strength against Superman's. Hulk could either be aggressive towards Superman or see him as a fellow powerhouse.
Snape would probably start off being rather aloof. He'd observe the Avengers' behavior and abilities before making any real moves to interact. He could be sarcastic towards them, especially if they make assumptions about him or his magic. But as time goes on, he might start to see their value and open up a bit more, sharing some of his magical knowledge.
Naruto would interact in a very enthusiastic way. He'd be in awe of the Avengers' powers and would want to learn from them. At the same time, he'd show off his own ninja abilities. He might bond with Hulk over their shared 'rage' - like Naruto has his nine - tailed fox anger and Hulk has his own. He'd also try to cheer up the more serious Avengers like Black Widow with his positive attitude. And he'd probably try to get them all to do some ninja training together.
Supergirl would probably start by introducing herself and her powers. The Avengers would likely be in awe of her abilities. They might ask her to join them on a mission right away. Supergirl could say yes and then start showing off her skills during the mission.
In fanfiction, Venom could interact with the Avengers in many ways. For example, he might initially be seen as a threat and the Avengers try to subdue him. But then they could discover that he has some common enemies, like certain powerful villains who are a menace to both him and the Avengers. So, they could form an uneasy alliance.
The Avengers and the Eternals could interact in a variety of ways. The Hulk might be intrigued by Gilgamesh's strength. Black Widow could try to figure out the Eternals' motives. And on the Eternals' side, Sersi might befriend Scarlet Witch and learn about her magic. There could also be some friendly competitions between the two groups, like a race between Quicksilver and Makkari.
In a fanfiction scenario, Superman's ability to fly could give Naruto a new perspective on combat. Naruto could learn to use the airspace more effectively. He might even develop new jutsu that are based on aerial combat, inspired by Superman. And Superman could learn from Naruto's ability to sense chakra. This could help him detect hidden threats or enemies that are using some form of energy cloaking device in his own world.
Superman has super strength, flight, heat vision, etc. X - 23 has enhanced strength, speed, and her claws. If they were in a fight together, Superman could use his flight to gain an aerial advantage and X - 23 could use her speed to quickly move around on the ground. His heat vision could be used to blast enemies from a distance while she could use her claws for close - combat.
Brightburn's powers are similar to Superman's but with a malevolent twist. When they interact, it could be that their super strength clashes in a way that causes massive destruction around them. Their flight could lead to high - speed aerial battles, with each trying to outmaneuver the other. And their heat vision could cross, creating intense energy bursts.