Well, one possibility is that Tony could replace Peter in a mission. Maybe Peter gets injured and Tony steps in to finish what Peter started. It could also be about Tony taking over Peter's role in a social or school setting within the fanfiction world.
Obviously, Tony and Peter are the main characters. Tony, with his genius intellect and wealth, and Peter, the young and spry superhero. There could also be other characters like Pepper Potts who might be involved in the story, perhaps trying to mediate between Tony and Peter or having an opinion on Tony replacing Peter.
In the 'harley replaces peter fanfiction', it could be that Harley steps into Peter's life. For instance, she could start living in Peter's neighborhood and interact with his friends and family. She would then deal with the same kind of threats that Peter has to handle, but with her own brand of problem - solving. She might be more brash or use her engineering skills more directly compared to Peter's more traditional superhero approach.
Obviously, Harley would be one of the main characters as she is replacing Peter. And characters like Aunt May could still be in the story. She might be a bit confused at first about this new person in Peter's place.
Peter could stand up to Tony. By showing his strength and not taking Tony's meanness lying down, he might earn Tony's respect. For instance, if Tony makes a snide comment, Peter could give a smart comeback that makes Tony see him in a new light.
One aspect to consider in 'possessive Tony and Peter fanfiction' is the nature of their relationship. It might explore themes of protection. Tony could be possessive in a way that he wants to keep Peter safe from the various dangers in the Marvel universe, like powerful villains.
Yes, there are likely some fanfictions out there with this premise. Fanfiction often explores unique and unexpected relationships between characters. Writers might create a scenario where Peter Parker is scared of Tony Stark for various reasons, like Tony's power, his temper, or some miscommunication between them.
Well, it could be that in the fanfiction, they argue about technology. Peter, being the brilliant young mind that he is, might have different ideas on how to use or develop Stark tech compared to Tony. Tony is more experienced and perhaps set in his ways, so when Peter challenges him, an argument ensues.
Well, a simple fanfiction idea could be that Peter loses his real father at a young age and Tony fills that void. Tony starts teaching Peter things like how to fix cars or build advanced technology, just like a dad would teach his son useful skills.
One possible fanfiction could be about Peter seeing Tony as a father figure. Maybe Peter gets into some trouble at school, like a bully situation, and Tony steps in to give him advice on how to handle it. Tony could share his own experiences of facing difficulties when he was younger, and through this, their bond as a sort of father - son duo deepens.