It depends on the context. If it's set in Tony's world with his high - tech gadgets, he might seem more dominant at first. He could use his intelligence and technology to try and outwit Surtar. For example, he could create some sort of energy - dampening field to hold Surtar back.
One idea could be that Tony tries to use his technology to control Surtar's power for some noble purpose, like saving a world from a different threat. But he quickly realizes it's a much more dangerous task than he thought.
I'm not sure who Tony specifically is in this fanfiction without reading it. It could be an original character created by the author, or perhaps a reimagined version of a known character in a particular fictional universe.
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.
In most kerry and tony fanfiction, Kerry is often depicted as brave. For example, in many stories, Kerry is the first to face challenges. Tony, on the other hand, is usually more of a thinker. He comes up with plans to solve the problems they encounter.
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.
Tony would likely be defiant. He's not the type to cower in the face of danger. He might immediately start looking for weaknesses in Thanos' setup and try to escape on his own terms.
Well, in the 'Avengers Tony is a God' fanfictions, Tony's character evolution is really interesting. His technological prowess is often magnified to a god - like level. For example, he could have the power to create and manipulate matter at will. This not only changes his relationship with his fellow Avengers but also how he views himself. He may struggle with the newfound power and the responsibility that comes with it, just like in the original stories but on a much grander scale.
One possible aspect could be their adventures together. Maybe they explore new galaxies in the fanfiction. Tony with his technological genius could create amazing devices to help them on their journey, while Starg might have some unique powers or knowledge that complements Tony's skills.