Some fans would be very shocked. They are used to seeing Spider - Man as a friendly neighborhood hero and an ally of the Avengers. If he were to hurt them, it would be like a betrayal of the image they have of him. They might feel angry at the character for a while until the story unfolds more and explains his actions.
Spider - Man would probably be shocked at first. He looks up to the Avengers and being kidnapped by them would be the last thing he expects. He'd likely try to talk his way out, using his quick wit and charm. He might start by asking why they're doing this and try to convince them that they've made a mistake.
Spider - Man would be very confused. He would feel betrayed because he thought the Avengers were heroes he could trust. He could start by asking them why they are doing this. If they don't give him a satisfactory answer, he might try to escape in a sneaky way, using his spider - like abilities to find a weakness in their capture setup while still trying to reason with them.
Spider - Man would probably be defensive at first. He's used to working alone most of the time, and being interrogated by the Avengers would seem unfair to him. He might crack some jokes to ease the tension, but also firmly state that he's a hero too.
They would probably have a range of reactions. Some might be entertained, while others would be more critical. Stark might joke about the science in it not being as good as his own tech.
Their dynamics would change a great deal. There would be a lot more tension. Some members might blame themselves or others. For example, Iron Man could be at odds with Captain America if they had different ideas on how to handle the situation. Their usual teamwork might break down as they are all dealing with grief in different ways.
Spider - Man would likely be confused at first. He respects the Avengers and can't understand why they are suddenly after him. He might try to talk to them, to explain that he's innocent. For example, he could swing up to Captain America and start pleading his case.
He would probably try to avoid them at first. Spider - Man is used to being on his own and fighting his own battles. He might use his agility and web - slinging skills to escape from the Avengers.
Spider - Man would probably be very confused at first. He looks up to the Avengers and would wonder why they are after him. He might try to talk to them and explain that there has been a mistake.
The Avengers would be very concerned. Captain America would immediately take charge of the situation, trying to keep everyone calm while they assess Spider - Man's injuries. Iron Man would start scanning for the best way to treat him, using his high - tech equipment. Thor might offer some of his Asgardian knowledge of healing, if there was any. Black Widow and Hawkeye would be on guard, making sure there were no further threats while the team focused on Spider - Man.
Well, Thor might be a bit confused at first. He's not used to the modern Earth stuff like Peter's high - tech suit. But he would soon get into it and cheer for Peter during the action scenes. Bruce Banner, on the other hand, would be interested in the science behind Peter's powers and the technology in his suit. He might be muttering to himself about how it all works. Clint Barton would be making sarcastic remarks here and there, like 'That kid's got more guts than sense sometimes.' The Avengers' reactions would be a mix of pride, amusement, and constructive criticism as they watch Peter's adventures in the movie.