Well, one key element is to have a unique take on the existing Harry Potter world. Maybe your OC (original character) could be a new student at Hogwarts with a special ability that's not common in the books. Another important part is to keep the magic system consistent. You can't just make up new spells that completely go against what J.K. Rowling has established. Also, the relationships your OC forms with the canon characters, like Harry, Hermione, and Ron, are crucial. For example, they could be friends, rivals, or even have a romantic interest in one of them.
Give your OC a really distinct personality trait. For example, if they're super clumsy but also incredibly smart when it comes to magic theory. Another way is to give them a unique appearance, like having bright purple hair that always seems to be on fire (in a magical, not dangerous way).
Well, 'OP' in the context of this 'Fury Tries to Kidnap OP Harry Potter Fanfiction' could be the main character that Fury is targeting because of their special powers. Maybe it's a new character created by the author with unique magical abilities that Fury, for some reason, wants to get his hands on. It could be someone with a combination of different magical skills from the original Harry Potter universe, like being able to perform extremely powerful spells without a wand or having the ability to control all types of magical creatures.
Well, 'op' usually stands for 'overpowered'. So it might mean that the Harry Potter fanfiction in question has characters or elements that are overly powerful, perhaps deviating from the original power balance in the Harry Potter universe.
The 'harry potter is op shirou emiya fanfiction' might be a creative blend of two different fictional universes. Shirou Emiya is known for his combat skills and determination in the Fate series. In this fanfiction, within the Harry Potter setting, he could be OP perhaps by having his unique magecraft abilities that are not typical of the magic in the Harry Potter world. For example, his projection magic could give him an edge over the normal spells used by wizards. This might lead to interesting plotlines like him facing off against Voldemort or helping the Hogwarts students in a way that defies the normal rules of their magic. It could also be a story about how he adapts to the new magical environment while still maintaining his OP status.
One idea could be that Harry discovers a hidden centaur community in the Forbidden Forest. He's initially scared but soon realizes they have a deep connection to magic that Hogwarts has not taught. He starts learning from them, about their archery skills and how they communicate with nature.
Well, if Harry Potter becomes a genie in fanfiction, he could use his magic in very different ways. He might be able to grant wishes, which would be a huge change from his usual spell - casting. For example, he could grant the wishes of his friends like Hermione and Ron. Maybe Hermione would wish for all the knowledge in the world to be easily accessible, and Harry as a genie could make it so.
One example could be a fanfic where Harry has the ability to control time without any limits, which is much more powerful than the time - turning devices in the original series. Another might be a story where Voldemort is made invincible and can defeat any opponent with a single spell, completely overpowering the other characters.
In a great number of fanfictions, Harry is indeed made into an OP magus. This is because it allows for more creative freedom. The author can have Harry perform amazing feats of magic, like creating new spells or having an unrivaled control over magic. It also makes for interesting interactions with other characters, as his OP status can either inspire admiration, envy, or fear among them.
Yes, in many fanfictions, Harry can be depicted as an OP (overpowered) assassin. Writers often like to take established characters like Harry and give them new, extreme abilities, and the role of an assassin allows for a lot of creative freedom in terms of combat skills, stealth, and a mysterious backstory.