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 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.
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 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.
One reason could be that they suspect him of being involved with a new villain's scheme without having all the facts. So they act preemptively and capture him.
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.
One reason could be a misunderstanding. Maybe some events were misinterpreted, and the Avengers thought Spider - Man was involved in something bad. For example, if there were some crimes that seemed to have Spider - Man's fingerprints all over them, but in reality, he was being framed.
The Avengers might capture Spider - Man if they suspect him of being involved with a new, unknown threat. For example, if there are strange crimes happening in the city and Spider - Man is seen at the scene every time, they could assume he's part of it.
Spider - Man could use his agility and web - slinging skills to escape. He could swing between buildings, making it difficult for the Avengers to follow him. His small size compared to some of the Avengers also gives him an advantage in hiding in tight spaces.
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.
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.