Some of the Avengers, like Hulk, might be a bit wary at first. But Morgan, being smart and confident, would quickly win him over. Black Widow could see a lot of Tony in Morgan and bond with her over their shared experiences. They could exchange stories about Tony, and Morgan could show the Avengers her new inventions that are inspired by her father's work. She could also ask the Avengers for help in dealing with a problem in her future world, and they would jump in to assist her.
The Avengers might initially be shocked to see Morgan Stark all grown up. Then, they could start interacting with her in a very friendly way, like she's family. Thor might be very protective of her, remembering Tony. Captain America could be impressed by her leadership skills.
Perhaps in the fanfiction, the Avengers meet future Morgan Stark who has been trying to carry on her father's legacy. She might be leading a new group of heroes, and the Avengers could team up with them to face a common enemy. For example, she could have developed advanced Iron Man - like suits for her team. The story could also explore how the Avengers react to seeing the grown - up daughter of Tony Stark and how she has been influenced by her father's sacrifice.
Well, she could have a mentor - mentee relationship with Bruce Banner. He could help her with the scientific aspects of her father's work. And she might be a bit scared of Hulk at first but then realize that he's just as much a part of the team as the others. With Hawkeye, she could learn about precision and focus in combat. Also, she could bring a new dynamic to the group, being the younger and more inexperienced one, but also having fresh ideas and a different perspective based on her unique upbringing as Tony Stark's daughter.
Some fanfics depict Howard Stark as having unexpected encounters with the Avengers, perhaps during time travel or alternate universes, leading to interesting plot developments and character dynamics.
The son could be in awe of the Avengers at first. He might look up to Captain America for his leadership and sense of justice. He could try to learn fighting skills from Black Widow or Hawkeye. And with Thor, he could be fascinated by the Asgardian's powers and stories. He would probably be eager to prove himself to them, especially since his father is such an important part of the team.
Future Loki might interact with the Avengers in a cautious way. He knows their past opinions of him and tries to prove himself. He could start by sharing small bits of useful information. For example, he might tell Iron Man about a weakness in a new enemy's technology.
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.
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.
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.