Maybe Tony has a special interest in Harley in the fanfiction. His focus is completely drawn to Harley, so he ends up ignoring Peter. It could be that Harley has some unique qualities or abilities that Tony finds more appealing at the moment.
Maybe Tony has to focus more on Morgan's needs at that moment and doesn't have enough time for Peter.
Well, it could be that Tony is focused on protecting Morgan and sees Peter as capable of handling himself, which leads to him ignoring Peter. And Peter might get hurt in a dangerous situation that he wasn't fully prepared for.
Peter may try to get Tony's attention back. He could show off his own skills or achievements in an attempt to remind Tony of his value. For example, he might go on a solo mission and do an amazing job, hoping that Tony will notice him again.
Maybe Peter sees Harley having something he desires in the fanfiction, like more popularity or a closer relationship with a certain character.
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 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.
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.
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.
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.
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.