Well, in many fanfictions, the Avengers protect Peter by always having his back in battles. For example, Captain America might shield him from incoming attacks with his iconic shield. They also offer him guidance. Tony Stark could be constantly giving him advice on how to improve his suit and combat skills.
Because Peter is often portrayed as a young and inexperienced hero in fanfiction. He's like a little brother to the Avengers, so they feel a sense of responsibility to protect him.
One good example could be a fanfic where the Avengers shield Peter from a powerful villain who has a vendetta against him. They form a protective perimeter around him during a battle, with Thor using his lightning to create a barrier and Iron Man's suit systems on high alert for any incoming threats.
The protectiveness aspect is appealing because it shows the family - like bond within the Avengers. Peter is often seen as the youngest and most vulnerable, so when the Avengers protect him, it's like a family looking out for their own. It also adds an element of safety and security to Peter's character, which fans like.
In some fanfics, Peter might be exposed to a dangerous new technology. The Avengers, led by Bruce Banner, use their scientific knowledge to protect Peter. They analyze the technology and find ways to counter its effects on Peter. Natasha Romanoff also uses her espionage skills to track down those who are behind the threat. The Avengers' diverse skills are all utilized to keep Peter out of harm's way, which is a common and great theme in 'Avengers Protective of Peter' fanfics.
One great Protective Peter Parker fanfiction is 'Spider's Shield'. In this story, Peter is extremely protective of his friends and family in the face of new threats in New York. Another is 'Peter's Protective Instincts Unleashed' which shows how he goes to great lengths to keep those he loves safe. There's also 'Protective Peter: The Guardian of Queens' that focuses on his local protectiveness in Queens.
In fanfiction, Protective Peter Parker is often very vigilant. He always has his spider - sense on alert for any potential danger to his loved ones. He's also quick to act, like a spider pouncing on its prey when he senses a threat. For example, he might immediately swing into action if he sees someone he cares about in a dangerous situation.
One common theme is redemption. The Avengers might have wronged Tony in some way before, and now they are being protective as a form of making it up to him.
One great fanfic is 'Avengers: Shielding Iron Man'. In this story, the Avengers go to extreme lengths to protect Tony from various threats. It shows their loyalty and care for him in a really engaging way.