Well, there could be a lot of chaos and cooperation. Maybe the Agents of SHIELD with their unique skills in espionage and handling strange threats could offer some fresh perspectives to the Avengers. For example, Fitz could help Tony Stark with some new tech ideas, while Coulson's leadership could guide the Avengers in a more covert operation.
In a fanfiction where they meet, it might start with some misunderstandings. The Avengers are used to dealing with big, global threats in a very direct way, while Agents of SHIELD often works in the shadows. But once they realize they can complement each other, they could form an unstoppable force. Daisy could use her powers to assist Thor in a battle, and Natasha Romanoff could teach some of the Agents of SHIELD more advanced combat skills.
Well, Tony Stark would probably be quite cocky around the Agents of Shield at first. He might make sarcastic remarks about their technology compared to his. But then he'd realize they have some unique skills and knowledge. Steve Rogers, on the other hand, would be more respectful and interested in their mission. He'd see them as comrades in the fight against evil. Natasha Romanoff might find some kindred spirits among the female agents of Shield like May. They could share their combat experiences and spy techniques.
The story could start with a call for help. Maybe an enemy that the Agents of SHIELD can't handle alone is causing havoc. So they reach out to the Avengers. Then there would be a period of getting to know each other. Some characters might not trust each other at first. But as they face challenges together, like fighting a powerful super - villain, they start to bond.
One idea could be that the Avengers need the Agents of Shield's help to track down a new, powerful and elusive villain who has technology that can disrupt the Avengers' powers. The Agents use their espionage skills to gather intel while the Avengers provide the muscle when it comes to confronting the bad guy.
Well, the plot could involve the Agents of Shield having to team up with the Avengers to stop a common enemy. Maybe a powerful alien threat or a super - powered villain that neither group can handle alone. The Agents could bring their espionage and covert ops skills, while the Avengers contribute their raw power.
In Avengers fanfiction, Phil Coulson is often considered one of the best Shield agents. He is highly dedicated, intelligent, and has a deep understanding of the Avengers. Another great one could be Maria Hill. She is tough, strategic, and can handle high - pressure situations well. And then there's Clint Barton, who combines his excellent archery skills with his Shield agent training.
Definitely Coulson and Iron Man. Coulson is a big fan of Iron Man in the show, and seeing them interact would be great. Iron Man's sarcasm and Coulson's more straight - laced nature would create some really interesting banter.
One interesting storyline could be a crossover where Agents of Shield agents have to team up with the Avengers to stop a powerful alien threat that neither group could handle alone. This would involve a lot of character interactions, like Coulson trying to give orders to Iron Man or Natasha Romanoff teaching some of the Shield agents her spy skills.
Definitely Coulson. He has such a rich backstory and his relationship with both the Agents of Shield and the Avengers (in an indirect way) is very interesting. His resurrection in Agents of Shield also provides a lot of potential for fanfiction. You could explore how he copes with being brought back to life and his new purpose.
Another storyline might be a time - travel plot where the agents go back in time to prevent a major event that would have led to the downfall of the Avengers. They could encounter younger versions of the heroes and change the course of history. This would involve a lot of character development and exploring different timelines.
Skye (Daisy Johnson) is also very popular. Her journey from a hacker to a powerful Inhuman is fascinating. Fanfiction often delves deeper into her powers and her role in both Shield and in relation to the Avengers. She has a complex personality which gives a lot of room for creative writing.