He might be a wealthy sponsor of the team. He loves the team so much that he decides to use his resources to give them a great surprise. Maybe he's a big fan of the sport and has a lot of money to invest in making the team happy and more competitive.
Tony could also be a long - lost former team member who comes back with a bang. He has some great news or a gift for the current team. He remembers all the good times and wants to contribute something positive to the team he once belonged to, so he plans this big surprise.
Tony could be the team captain. As the captain, he has a special bond with the team members and might want to do something special to boost their morale. He would know what kind of surprises would really make an impact on them.
Perhaps Tony surprises the team by getting them all new equipment. He noticed that the old ones were a bit worn out. He spends a lot of time researching the best stuff for each member and then presents it to them all at once. It could also be that he arranges a special training session with a world - famous coach without them knowing in advance.
There could be some young and brilliant inventors like Peter Parker. His fresh ideas and quick thinking would be an asset to the team.
In this fanfiction, Tony might also meet Loki. Loki could be either a friend or a foe to Tony. He might try to trick Tony for his own amusement or they could end up working together against a common threat to Asgard.
He would surely meet T'Challa, the Black Panther. They might have in - depth conversations about leadership and protecting their respective countries.
Obviously, Tony is one of the main characters. There might also be characters like Steve, who could be Tony's friend or rival in the fanfiction. Natasha could be another important character, adding her own skills and personality to the mix. And then there's Bruce, the scientist, who could play a crucial role in the stories.
It could be Rhodey. As Tony's long - time friend and fellow Avenger, Rhodey would be eager to see him and would likely be among the first to be informed of his return.
It could be that the Tony fanfiction doesn't align with the team's vision or values. For example, if the team is trying to create a certain image or brand, and the fanfiction goes against that in some way, they would neglect it. Also, if the fanfiction has a lot of inaccuracies or goes too far from the original source material regarding Tony, the team might choose not to give it any attention.
Tony may develop a darker side. The allure of the Infinity Stones' power could corrupt him. He might start to make decisions that are not in the best interest of the world but rather for his own gain or to satisfy his newfound thirst for power. This would create a lot of conflict, both within himself and with his friends, and add a whole new dimension to the fanfiction.
Maybe a brilliant biologist who has developed a way to enhance human physical abilities through genetic manipulation. A former S.H.I.E.L.D. agent who has inside knowledge of all kinds of secret operations and is an expert in combat and espionage. Also, a young inventor from a small town who has created some amazing but unrefined gadgets that catch Stark's attention.
Pepper Potts. She is very close to Tony and knows him well. She might notice some strange behavior or small signs that lead her to suspect he has hidden powers. For example, he might unconsciously use his powers in a moment of stress or danger when he thinks no one is looking.