It would be a very strange situation. Since fanfiction often contains alternate versions of the story or different characterizations, if Harry Potter somehow got access to it, he might be confused. For example, if he read a fanfiction where his relationship with Hermione was different than in the real story, it could mess with his perception of their friendship.
If Harry Potter were to use visual novels fanfiction, it could potentially disrupt his understanding of his own life and the world around him. Fanfiction can deviate significantly from the original canon. He might start to question things like his destiny or the true nature of his relationships. For instance, if he read a fanfiction that painted Snape as a much more benevolent character than he seemed in his own experience, it could make him reevaluate his views on Snape. However, this is all very hypothetical as the two exist in different fictional planes.
If Harry were to use the Force in fanfiction, it would be a game - changer. His relationships with his friends might change as they try to understand this new power of his. He could use the Force to explore hidden places that are protected by magic, finding new secrets. His enemies would be more afraid of him as he combines magic and the Force, making him a more formidable opponent. For instance, he could use the Force to break through powerful dark magic barriers that he couldn't with just magic.
He might also be a bit confused at times. Some fanfictions deviate a lot from the real events in his life. For example, if there's a fanfiction where he has a completely different upbringing, it would be strange for him to read about. He could also feel a sense of flattery that so many people are interested in his story and want to create their own versions of it.
He might be really surprised. Fanfiction often contains different interpretations of the characters and the story. He could be amused by some creative ideas, or perhaps a bit confused if the fanfiction goes too far from the original story he knows.
In a 'Harry Potter in Gotham' fanfiction, Harry might team up with some of Gotham's heroes. For example, he could share his knowledge of magic with Batman. Harry's magical creatures knowledge could also come in handy. He might introduce Thestrals to Gotham as a new form of transport for the heroes during emergencies. Also, his ability to communicate with snakes could potentially help in dealing with some of the more reptilian - like villains in Gotham.
The idea of Harry Potter with a gun is quite interesting. One possibility is that he gets the gun from the muggle world accidentally. He might initially be confused about how to use it but then realizes its potential. This could lead to new alliances in the wizarding world. Some wizards might be intrigued by this new weapon and want to learn more about muggle technology, while others might be afraid and try to confiscate the gun from Harry.
It would be really strange. He might be very confused as fanfiction often contains different interpretations and sometimes wild ideas that are far from his own experiences. He might think it was some kind of strange magic that created these alternate stories about him and his friends.
Well, he could bring his magic skills to the team. Maybe he'd use spells like 'Expelliarmus' to disarm villains before the Avengers could even react. His ability to apparate could also be useful for quick getaways or surprise attacks on enemies.
In some fanfictions, if Harry Potter becomes a warlock, he might gain even more powerful magic. He could have greater control over spells and be able to perform magic that was previously thought impossible. For example, he might be able to manipulate time in a more complex way or have the power to instantly transport himself anywhere in the wizarding world without the need for a Portkey or Apparition.
Well, he'd probably bring his magical skills to the military. Maybe he could use spells for things like reconnaissance. For example, he could use the invisibility cloak to spy on the enemy, or use the Patronus charm to send messages in a secure way. His quick thinking and combat experience from fighting Voldemort would also be useful in military strategies.
Well, it would be a really strange scenario. Magic and guns don't really go together in the traditional Harry Potter world. But if Harry had a gun, he might use it in a moment of extreme danger when his magic fails him. Maybe against some dark creatures that are immune to certain spells.