A great time machine story idea could involve a group of scientists who create a time machine. But when they test it, they accidentally bring back a dangerous virus from the past that was extinct in their time. The story could then revolve around their attempts to contain the virus and send it back to its original time without causing a global pandemic.
In a fanfiction, Sakura and Neji could be sent back in time by an enemy's powerful jutsu. They find themselves in a time when the ninja clans were more divided and at war. Sakura uses her intelligence and Neji his combat skills to survive. Along the way, they start to understand each other better and work towards a common goal of finding a way back home. Their actions in the past also start to have a ripple effect on their present - day world.
Well, start with the world - building. In a supernatural fanfiction with a God, the world has to be different from ours. Decide on the rules of this world. For the OC, give them a distinct personality and backstory. If the God in your story has the power of prophecy, the OC could be someone trying to avoid a foretold doom. Build the plot around how they interact with the God's powers and intentions.
To create an intriguing plot for an Ia x Yukari fanfic, start with a mystery. Maybe something strange is happening in their world that only their combined skills can solve. For instance, a series of magical disappearances. Then, as they investigate, they start to learn more about each other. Another idea is to have a conflict between them at the start, like a misunderstanding over the use of a powerful spell. As they work through it, the plot thickens.
One idea could be Noctis traveling back in time to prevent the fall of Insomnia. He could use his knowledge of future events to stop the Niflheim invasion before it starts. Maybe he teams up with his father and the Crownsguard in their prime to fortify the city's defenses.
To develop an interesting plot, think about the stakes. What does the character stand to lose or gain? If it's a story about a young athlete, the stakes could be winning a championship to get a scholarship. Then throw in obstacles. The athlete gets injured right before the big game. You can also play with time. Have the story jump back and forth between different moments in the character's life to build tension and mystery.
First, study the characteristics of both. The Roman Legion had strict formations and strategies. In a fanfic, you could make a legionnaire the main character. He could be thrust into the chaos of Westeros, with its different houses vying for the Iron Throne. Maybe he uses his Roman military knowledge to train a group of outcasts into a formidable force. This new force could then play a role in the power balance, similar to how the Unsullied did in the original series.
To create a great plot for a Gravity Falls male OC fanfiction, consider the setting. Gravity Falls is full of strange and wonderful places. Your OC could discover a hidden part of the forest or an old abandoned building with a dark secret. His interactions with the other characters are key too. He might teach Dipper a new way to approach mysteries or help Mabel with one of her crazy schemes. And always keep in mind the overall mood of Gravity Falls - a mix of mystery, humor, and a touch of spookiness.
One interesting plot idea could be the protagonist using the time machine to visit key historical events that were only hinted at in the original 2002 movie. For example, they could go back to the very beginning of the Eloi and Morlock split and try to prevent it. This would add a whole new layer of depth to the story.
Well, perhaps in this fanfiction, Rock Bass travels to the future. In the future, Mega Man has become a legend and Rock Bass discovers that a new evil has emerged, one that is using the technology of the future against the good. Rock Bass teams up with future versions of Mega Man's allies to stop this threat and in the process, learns valuable lessons about the power of friendship and technology. He then takes these lessons back to his own time to better protect it.
One idea could be to focus on a young, Force - sensitive character from a previously unheard - of planet. This character discovers an ancient Jedi artifact that holds the key to a long - forgotten power. But a Sith cult is also after this artifact. The character then has to journey across the galaxy, making new allies like a gruff but kind smuggler and a wise old alien sage, all while being chased by the Sith.