Maybe there's a plot where the Justice League is facing a threat that has to do with advanced technology that they can't quite understand. Peter Parker, with his scientific knowledge from his own world and his experience with high - tech gadgets like his web - shooters, could be the key to helping them solve the problem and defeat the villain.
One idea could be that Peter Parker gets accidentally transported to the Justice League's universe. He could initially be seen as an outsider, but then prove his worth with his spider - sense and acrobatic skills during a battle against a common enemy. For example, against a powerful alien invader where his ability to quickly assess threats and react would be very useful.
Peter could be integrated into the Justice League in a fanfiction by having a shared enemy. Suppose a villain is using technology from both Peter's world and the Justice League's world. This forces them to team up. Peter's agility and the League's superpowers combined could make for an interesting dynamic. He could learn from the more experienced heroes, and they could in turn learn from his resourcefulness and his ability to operate on a tight budget with his self - made gadgets.
One idea could be that Peter Parker gets injured during a fight with a villain and has to use crutches. His friends at school might be really concerned and try to help him out, like Ned bringing his books for him. In the fanfiction, it could show how he still tries to be Spider - Man even with his injury, perhaps using his web - shooters in creative ways to move around while on crutches.
One idea could be that Tsunade is brought to the Justice League's universe through some sort of magical portal mishap. She could use her medical ninjutsu skills to help treat injured Justice League members, like when Superman gets hurt by a kryptonite - based weapon. Her tough - as - nails attitude would also make for some interesting interactions with Batman, who might be intrigued by her no - nonsense approach.
One idea could be that they meet during a multiverse - related crisis. Peter's quick thinking and Thundra's strength complement each other as they fight side by side. As they spend more time together, they start to develop feelings. Eventually, they decide to get married in a ceremony attended by various superheroes from different universes.
Well, in a fanfiction where Peter Parker turns into a kid, perhaps he could end up at his old school. He'd be faced with bullies again, but this time he has the knowledge and experience of being Spider - Man, even if he's in a kid's body. This could lead to some interesting scenarios where he uses his smarts to outwit the bullies without using his powers directly. Or, he could befriend his younger self's friends in a whole new way, seeing them from a different perspective.
Maybe there's a multiverse event that causes Peter Parker to be transported to the DC universe. He meets Superman first, and Superman is initially a bit wary of this strange new hero with spider - powers. But as they face a common enemy, like Lex Luthor who has somehow gotten his hands on some Oscorp tech, they learn to work together. Peter can use his scientific knowledge from his own world to help Superman figure out how to disable the dangerous tech.
One idea could be that Peter Parker and Captain Marvel are teamed up to face a powerful cosmic threat that's approaching Earth. They initially clash due to their different approaches - Peter is more street - level and cautious, while Captain Marvel is bold and used to dealing with large - scale threats in space. But as they get to know each other better, they start to combine their powers effectively, with Peter using his spider - sense to anticipate the enemy's moves and Captain Marvel delivering powerful blows.
Another fanfiction concept could be that Peter's school starts a new dance club. Peter joins to keep an eye on a suspect he thinks might be involved in some criminal activities. But as he participates in the club, he falls in love with dancing itself. He then has to figure out how to balance his detective work within the club and his growing passion for dance without blowing his cover as Spider - Man.
One idea could be that Peter Parker gets a prosthetic after a particularly dangerous battle with a villain. Maybe his leg is severely injured and he has to adapt to the new prosthetic while still maintaining his superhero duties. He could struggle at first with the balance and movement, but with his determination, he eventually masters it and even modifies the prosthetic to have some special features like enhanced jumping ability.
One idea could be that Peter uses his spider - abilities to help on the farm. For example, he can use his super strength to lift heavy farming equipment or his agility to quickly harvest crops. Maybe he becomes a farmer to get away from the chaos of the city and superhero life for a while, finding peace in the simple life of farming.