Thor could also be a great character to focus on. He has his Asgardian powers and a different cultural background compared to the others. In a fanfiction with Doctor Strange and the Avengers, he could be the one who has the most trouble understanding Doctor Strange's magic at first. His reactions to the strange magical situations and how he tries to incorporate his own strength and honor into the mix could create some really engaging storylines. Also, his relationship with other Avengers and how it changes with the addition of Doctor Strange's presence could be explored.
Definitely Doctor Strange and Loki. Loki is a master of trickery and Doctor Strange is a master of magic. Their interactions would be full of mind games and magic duels. Loki might try to deceive Strange, but Strange would see through his illusions with his magic.
Captain America's protege would be an interesting choice. He has big shoes to fill, and seeing how he has developed in the absence of Captain America would be engaging. He might struggle with living up to the legacy, but at the same time, he could bring his own unique style and leadership to the group during the reunion. His relationships with the other young Avengers, especially those who knew Captain America well, could be a major part of the story.
I think Spider - Man himself would be the most interesting. He's a young and relatively inexperienced hero compared to the Avengers. His different perspective and his unique powers like climbing walls and the spider - sense would add a lot of flavor to the story. He could also bring in a sense of humor and a bit of naivete that would contrast with the more jaded Avengers.
Captain America would be really interesting. His moral compass and leadership skills in a time - travel scenario would be fascinating. He has to deal with the changes in the past that the time travel causes, and also make sure the other Avengers stay on the right path. He might struggle with seeing his old world again and having to make choices that could change it further.
I think Daisy Johnson would be really interesting. She has her unique powers and a complex backstory from her time in SHIELD. In a crossover, she could interact with the likes of Thor. Maybe she could learn some new ways to control her powers from him, as he has experience with his own godly powers. And she could also show the Avengers her skills in combat and stealth that she learned in SHIELD. It would be fascinating to see how she holds her own among the super - powerful Avengers.
Loki could be a great focus in a fanfiction involving both. He has a history with the Avengers, but his wily and unpredictable nature could lead to some interesting interactions with the Agents of Shield. He could be playing his own game, pretending to help both groups while actually having his own agenda. It would be fun to write about how the Agents and the Avengers try to figure out his true motives and keep him in check.
I think the Doctor and Tony Stark would be an interesting pairing. They are both highly intelligent and have a knack for getting out of tough situations with their wits. They could bounce ideas off each other regarding technology and science, and probably argue a lot about whose tech is better.
Hulk would be an interesting character to focus on. Imagine the dynamic between him and Wolverine. They both have superhuman strength and a bit of a wild side. Their fight could be epic, but then they could also form an unlikely alliance. Also, Black Widow could add an element of mystery and stealth to the story. Her skills in espionage and combat could be useful in a plot where the team is trying to uncover a secret conspiracy related to Wolverine's past.
Batman and Black Widow would be really interesting. Batman is all about mystery and detective work in the shadows, while Black Widow is a master spy. They could learn a lot from each other's skills in stealth and intelligence gathering. Also, Thor and Batman could be a great focus. Thor with his god - like powers and Batman with his human ingenuity. Imagine Batman trying to figure out the science behind Thor's hammer while Thor is amused by Batman's determination in the face of the supernatural.
In my opinion, it would be Tony Stark. His relationship with Peter Parker is already quite complex. He is like a mentor to Peter, but at the same time, he has his own issues and motives within the Avengers. In a fanfic, we could explore how Tony's decisions regarding Peter affect the whole Avengers dynamic. He could also use his genius to develop new tech for Peter, which could lead to some exciting storylines. For example, creating a new suit for Peter that has some unique abilities that come in handy during a big battle against a powerful enemy.