In this fanfiction, Harry could be in a situation where he is magically linked to Tony Stark. Due to this link, he gains access to the concept of the arc reactor. He then tries to recreate it in the wizarding world with the help of Hermione's research skills and Ron's practical knowledge. They face many challenges as the wizarding world doesn't understand this Muggle technology at first. But eventually, they manage to build an arc reactor - like device that has the power to disrupt dark magic, which they use to defeat Voldemort in a completely unexpected way.
Well, another place to look could be Tumblr. There are often fanfic communities on Tumblr that might have what you're looking for. Some users post links to their fanfictions or reblog them. You might have to dig a bit, but it could be worth it. Also, don't forget to check any Harry Potter or relevant fandom - specific forums. People there might be sharing or discussing such unique crossovers.
Maybe Peter discovers an old, broken Arc Reactor and decides to fix it up. He could use his scientific knowledge to tinker with it and eventually get it working, which then gives him some new powers or abilities.
In this fanfiction, perhaps there's a big misunderstanding. Bucky has been led to believe that the arc reactor is some sort of key to a greater evil. So, without fully understanding its importance to Tony, he rips it out. This could then lead to a chain of events where Bucky has to face the consequences and try to make amends while Tony is fighting for his life.
Maybe he found it in an abandoned Stark Industries facility. It could have been left behind during some chaos and Peter, being the curious and resourceful guy he is, discovered it and decided to study it.
The arc reactor in fanfiction about Tony Stark is a really cool concept. It can be used to show the evolution of Stark's character. At the start, it might be just a technological marvel for powering his suit. But as the story progresses in the fanfic, it could become something more spiritual or emotional for him. It might represent his connection to his past, his father perhaps, and his journey to become a better hero. And the way different authors play with this idea in their fanfictions is really fascinating.
One possible plot could be that Harry is facing a new and powerful dark wizard threat in the wizarding world. He might need help from his friends, Hermione and Ron, to figure out the wizard's motives and weaknesses. Maybe he also needs the help of some long - forgotten spells or magical artifacts to defeat this enemy.
It could be Bucky himself if he's under mind control. He'd be the one directly causing harm to Tony by ripping out the arc reactor, so in that sense, he's the antagonist, even if it's not really his fault.
One possible plotline could be Peter using the arc reactor to enhance his existing abilities. For example, if he has spider - powers, the arc reactor could make them stronger. Another could be Peter having to protect the arc reactor from villains who want to steal it for their own evil purposes.
The arc reactor in fanfiction involving Stephen Strange can also be a source of conflict. Some might write that the energy from the arc reactor is disrupting the magical balance that Strange is trying to maintain. This could lead to a tense relationship between the two characters at first, but as the story progresses, they could find a way to work together to either control or utilize the arc reactor's power in harmony with magic.
Tony Stark himself is obviously a very popular character. He is the central figure associated with the arc reactor, and fanfictions often revolve around his experiences, emotions, and adventures related to it.