One way this could work is if there was a shared enemy. Let's say a powerful being that threatened both the wizarding world and the world of the Avengers. In order to combat this threat, a magical - technological alliance was formed. During this alliance, Tony Stark and a powerful witch (Hermione's mother) got close, and Hermione was born. This would create a really interesting dynamic in the fanfiction, with Hermione having the intelligence of her father and the magical abilities from her mother's side.
Well, one way could be through some sort of multiverse concept. Maybe in a particular alternate universe, the magical and technological realms collide in a way that allows for such an unlikely family connection. It could involve a powerful spell or some advanced Stark technology that messes with the fabric of reality and ends up creating this strange but interesting scenario where Harry Potter is reimagined as Tony Stark's daughter.
In fanfiction, it's about creative license. One way this could work is if there was a powerful magical or technological device that merged the two universes on a small scale. This device could have somehow altered reality in such a way that Hermione became related to Tony. This relationship could then lead to all kinds of new storylines, like Hermione using her magic to help Tony with his inventions or Tony teaching Hermione about modern technology, which she could then incorporate into her magical studies.
Well, in fanfiction, anything can be possible. It could be that some sort of magical time - space rift or a powerful spell gone wrong brings Harry Potter into the world of Tony Stark. Maybe a wizard in the Potterverse messes up a spell and accidentally transports Harry to the Marvel universe where he is then adopted by Tony Stark.
Another possibility is that he underestimates the importance of family. Tony has always been focused on his own achievements and the big - picture stuff. He might not realize how much his daughter needs him until it's too late.
Well, one way it could unfold is that Marinette inherits Tony's genius. She could use her skills in fashion (from her own background) and combine it with Stark tech to create amazing high - tech fashion. Maybe she'd design suits for superheroes that are not only stylish but also have advanced defense mechanisms. She might also struggle with the pressure of living up to her father's name in the world of technology and heroics.
One possible plot could be that the daughter discovers some dark secret about Tony's past, like his involvement in a project that had negative consequences for her mother. This revelation makes her angry and she decides to oppose him. She might team up with other villains who also have a grudge against Tony.
Often, his fatherhood in crossover fanfiction is depicted as a balance between his high - flying superhero life and family life. In a crossover with the Doctor Who universe, he might use his tech to travel with his child through time and space, all while teaching them valuable lessons about the consequences of meddling with time and the importance of different cultures across the universe. It's a complex portrayal that combines his genius, heroism, and new - found parental love.
Well, they could start off not getting along. Tony, being used to his high - tech world, might not understand Hermione's magic at first. But then, when they face a common enemy, like a villain who is both a threat to the wizarding world and the normal world. They realize they need each other's skills. Hermione's ability to think on her feet in magical situations and Tony's quick - witted engineering could make them a great team.
In this type of fanfiction, it could be possible through some dark magic or a hidden plot twist. Maybe a spell was cast long ago that altered the truth about Hermione's parentage. However, it goes completely against the original story's lore.
In fanfiction, anything can be possible. Maybe the author created a unique backstory where Hermione is the Doctor's daughter through some sort of time - travel or alternate universe scenario. For example, in a time - warped dimension, the Doctor could have had a relationship that led to Hermione's birth. It's all about the creativity of the fanfiction writer.