In a fanfic, Spider - Man could be injured while on a mission with the Avengers in outer space. Maybe they are exploring an alien planet and are attacked by some sort of bio - mechanical creatures. Spider - Man is separated from the group and gets severely injured by one of the creatures' acidic attacks. His injury makes it difficult for him to use his powers effectively, and the Avengers have to find a way to both get him back to Earth and find a cure for his injury.
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.
One idea could be that during a mission crossover, Spider - Man gets injured while trying to protect a civilian from an unexpected attack by a powerful enemy. Maybe he takes a hit meant for an Avenger and his suit's technology malfunctions, leaving him vulnerable.
He could be injured by a new and powerful villain that the Avengers and Spider - Man are facing together. The villain might have a weapon or power that can penetrate Spider - Man's suit and defenses, like a sonic blast that disrupts his spider - sense and then physically harms him.
Perhaps there's a new law or regulation in the superhero world that Spider - Man has broken, unknowingly. The Avengers, being the enforcers of sorts, attack him. Like, there's a rule about using certain powers in public and Spider - Man accidentally did it while saving people. The Avengers misinterpret his actions as blatant disregard for the law.
Well, it could be that an enemy of the Avengers and Spider - Man targets a fan as a way to get to them. Maybe this villain wants to use the kidnapped fan as bait to lure Spider - Man into a trap. The Avengers then have to work with Spider - Man to rescue the fan without getting caught in the villain's elaborate schemes.
One interesting storyline could be Spider - Man teaming up with the Avengers to fight a new super - villain that's a combination of different powers they've faced before. For example, a villain with the strength of the Hulk and the mind - control abilities of Loki.
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.
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.
Well, initially, the Avengers might underestimate Spider - Man. They think he's just a kid in a suit. But Spider - Man quickly shows them his skills. He could start by taking out Hawkeye's arrows mid - air with his webs. Black Widow would try to use her combat skills against him, but Spider - Man is too fast. The fight could then move to a more strategic level. The Avengers could use their combined powers to try and trap Spider - Man. However, Spider - Man's intelligence and quick thinking could help him find a way out. Eventually, they might realize they've been misled and join forces with Spider - Man.
One possible reason could be a misunderstanding. Maybe the Avengers think Spider - Man has been compromised by some sort of enemy influence. For example, if a powerful villain has the ability to control minds and they suspect Spider - Man is under that control, they would try to capture him to protect the world and also to try and break the control. Another reason might be that they believe Spider - Man has some information that is crucial for saving the world but he's being uncooperative, so they resort to capturing him. It could also be that there's some sort of new law or regulation in the superhero world that Spider - Man is unknowingly breaking, and the Avengers, as the enforcers of a sort of superhero code, feel they need to bring him in.