Yes, there are many fanfictions with this concept. It's an interesting idea that combines two beloved characters from the Marvel universe. Writers often explore how Peter Parker (Spiderman) would grow up with Tony Stark as his father, imagining different storylines and character developments.
There are indeed. Fanfiction writers like to play with the idea of family relationships in the Marvel world. Having Spiderman be Tony's son allows for new and unique story arcs. It could mean that Peter has a different support system, different moral guidance from Tony, and it might also affect how he deals with his enemies. Maybe he'd be more confident or more cautious depending on how Tony raised him.
Sure. In such fanfictions, it can lead to really cool scenarios. For example, Peter might have access to more advanced technology earlier, and Tony could train him in a more hands - on way. This could change the whole dynamic of Peter's superhero journey and his relationships with other characters like the Avengers.