One idea is to create an original character who is related to an existing character in the fandom. In a Supernatural fanfic, your OC could be a long - lost relative of the Winchester brothers. This instantly gives them a connection to the main story. Another approach is to make the original character a rival to the main character. In a Bleach fanfic, your OC could be a new Soul Reaper who challenges Ichigo's position as the protector of Karakura Town. And you can also have the OC be an undercover agent in the world of the fanfic, like in a James Bond fanfic, where your OC is a double agent working for a different organization.
You can start by giving them complex motivations and goals that don't neatly fit into typical good or evil categories. Let their actions be driven by a balance of various factors rather than a clear moral stance.
You can make the document part of the plot, like a hidden clue or a secret message that the characters need to discover.
The key is to give the police characters purpose and complexity. Maybe they have personal struggles that influence their actions. Or they could have unique methods for solving cases that add intrigue to the story.
You could create a character who is a rival pyromancer to Naruto. This character could have different techniques and a different moral code when it comes to using fire powers.
You can have existing characters like Handsome Jack be affected by time travel. For example, he could be sent back to a time when he was just starting his rise to power. This would show a different side of him, perhaps more vulnerable or idealistic before he became the tyrant we know. The Vault Hunters could then interact with this younger Jack and either try to change his future or be influenced by his earlier ideas.
You could create a character who is an expert in nanite technology. Maybe they come from a far - off land where they've been studying nanites for years. They arrive in the Naruto world to study how the chakra system might interact with the nanites.
Well, Levi is known for his stoicism. In the fanfiction, this could be shown when Hanji tells him she's pregnant. He might not show much emotion outwardly at first, but later on, you can see his care through his actions like making sure Hanji has a proper diet. Hanji's adventurous spirit can be part of the story too. She might want to explore new places even while pregnant, and Levi has to be the voice of reason. Their different traits can create interesting conflicts and also beautiful moments of harmony as they await the baby.
You need to make them fit naturally into the story. Don't force it. Let the political ideas evolve as part of the world-building and character development.
We can start by choosing a math concept, like addition. For example, in a story, a character could be collecting berries. At first, he has 3 berries, and then he finds 2 more. So in the story, we can write 'John had 3 berries, and when he walked further into the forest, he found 2 more. Now he has 3 + 2 = 5 berries.' This shows how we can use a simple math idea of addition in a story.
One way to do it is to start by thinking about your own experiences and emotions. Maybe a memorable event or a strong feeling could be the basis for a story idea.