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.
I think Thor could be really excited too. Thor loves a good warrior and Peter, with his spider - like abilities, would be an interesting addition to his view of heroes. Thor might be amused by Peter's small - scale heroics compared to his own grand battles and would enjoy seeing Peter's potential grow.
Black Bolt from the Inhumans would be really interesting. His power of destructive voice is so powerful that he has to be extremely cautious. In a fanfic, he could be the key to solving a major problem, but his inability to communicate easily (because of his power) could create a lot of tension and drama. The Avengers would have to learn to work around his unique situation.
One idea could be Peter Parker trying to prove himself to the Avengers. He could be given a difficult mission on his own, and through his own skills and determination, he not only completes it but also earns the respect of all the Avengers. For example, he might have to infiltrate a high - security Hydra base to retrieve important data. Another plot could involve Peter's relationship with Tony Stark within the Avengers context. Maybe Tony has to make a tough decision regarding Peter's safety and his role in the team, which causes some tension between them at first but eventually leads to a deeper bond. And a third idea is that the Avengers get mind - controlled and Peter has to find a way to break the control and save them, all while trying not to get caught by his now - enemy teammates.
Definitely Dr. Strange. He already has a connection to magic, so in a Harry Potter x Avengers fanfic, he could bridge the gap between the two worlds. He could learn new spells from the wizards and share his knowledge of the mystic arts. His ability to manipulate time and space would be really useful in the wizarding world, and he could help the Avengers and the wizards deal with threats that involve both magic and science.
Probably Steve Rogers. He has that all - American hero charm and he values loyalty and courage, which Peter clearly has. Steve would recognize those qualities in Peter right away and would want to get to know him better. He might see Peter as a symbol of the future of heroism and be eager to befriend him.
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.
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.
Thor would probably see Peter as a worthy warrior. He might offer to take Peter to Asgard to train in a different environment. He'd be like 'Young Parker, the fields of Asgard will make you stronger!'. Bruce would be concerned about Peter's safety. He'd constantly remind Peter to be careful with his powers. He'd say 'Peter, your powers are great but they can also be dangerous if not controlled properly.' And the Avengers as a whole would create a support system for Peter, each offering their unique skills and perspectives to help him in his future.
Definitely Percy and Tony Stark. Percy is this young, powerful demigod from a world of magic and myth, while Tony is a genius billionaire with high - tech gadgets. Their interactions would be filled with banter. Tony would be constantly trying to figure out how Percy's powers work and Percy would be both amazed and a little put off by Tony's arrogance at times.
Wolverine and Captain America would be a really interesting pairing. Wolverine's rough - and - tumble, no - nonsense attitude combined with Captain America's moral leadership could create some great interactions. They could also learn from each other's combat styles, with Cap teaching Wolverine some more strategic moves and Wolverine showing Cap some of his dirty - fighting techniques.