Who could be the main villain in 'harry becomes an avenger fanfiction'?

It could be a super - powered villain who has a vendetta against the Avengers. Maybe he sees Peter as a new and vulnerable target since he's just joining the team. This villain might have some connection to Peter's past that makes him especially interested in causing trouble for Peter and by extension, the Avengers.

Well, perhaps Harry discovers the Avengers through some magical means like a spell gone wrong that transports him to the MCU world. He could be in awe of their powers and decide to learn from them, and then try to incorporate their fighting styles into his own magical battles.

It could be Kabuto. Since he has a lot of knowledge about medical ninjutsu and experiments, he might see Naruto's robotic form as a threat or something he can use for his own evil purposes. He could try to control Naruto's robotic functions and turn him against his friends.

The Joker could be a great villain. Imagine if the Joker - like character emerged in the My Hero Academia world. Izuku, with his new Batman - inspired skills, would have to use his wits to outsmart this chaotic and unpredictable foe.

It could be Sam and Tucker. Since Danny has become a villain, his former friends would likely try to stop him. They would be the main antagonists from Danny's point of view now. They would use their knowledge of Danny and their own skills to try and bring him back to the good side.

It could be a new dark wizard who has been secretly plotting in the shadows. This wizard might be jealous of Harry's fame and power, and decides to make him disappear so that he can rise to power unopposed. He could have a group of followers who are experts in dark magic and are able to carry out his plan to make Harry vanish.

The Queen of Hearts would make a great main villain. Her tyrannical rule and quick temper in the original Wonderland story could be amplified in a fanfiction. She could be a powerful dark magic user who sees Harry as a threat to her rule and tries to stop him from achieving his goals in Wonderland.

It could be Ladybug. If Adrien turns villain, Ladybug would be the natural antagonist as she represents the good side. Their relationship would be completely flipped from what it was before. She would have to try to stop him from causing more harm, all while probably still having some feelings for the old Adrien.

Well, he could bring his unique water - controlling abilities to the Avengers. Maybe he'd be the one to put out the fires during big battles in the city. He might also form an interesting friendship with Thor, since they both have some connection to powerful elements.

Well, it could be that Peter starts off as a regular guy who is just a huge fan of the Avengers. Maybe he follows all their news, collects their merchandise. One day, he gets a chance to meet them somehow, like through a Stark Industries internship. Then he gradually proves himself useful to them and they start to train him. Eventually, he becomes part of the team, with his own unique skills like his spider - powers adding to the Avengers' strength.