One idea could be creating an OC who is a long - lost relative of one of the main characters in the Magnificent Seven. This OC could bring a new dynamic, perhaps with a secret past or a special skill that helps the group in a unique way. For example, if the OC is related to Vin Tanner, they might have a similar tracking ability but with a different approach.
One idea could be to introduce a new character who has a special skill, like being an expert archer from a far - off land. This character could initially be distrusted by the group but then prove their worth in a big battle. Another idea is to have a plot centered around a lost treasure that the group has to find while also dealing with a rival gang who wants it for themselves. Maybe the OC could have a personal connection to the treasure's origin.
A great plot for Magnificent Seven fanfiction might be a love story within the group. Perhaps one of the members falls in love with a local girl they are protecting. But there are complications, like her father doesn't approve because he thinks the man is too dangerous. And at the same time, they still have to face off against the bandits that are threatening the town. So it's a story of love and duty all mixed together.
A great idea for the fanfiction could be to develop a romantic sub - plot among the characters. Since they are in a group, there could be some unspoken feelings or a slow - burn romance that starts to develop between two of them. This could add a new layer of depth to the story and also show a different side of the characters, as they navigate their feelings while still dealing with the main adventures and challenges in their world.
One idea could be an OC who is a hybrid of two of the deadly sins, like pride and envy. This OC could struggle with the internal conflict of these two powerful emotions. For example, being envious of the power of other characters while also being too proud to admit it or ask for help. Another plot could be an OC who is on a quest to redeem the Seven Deadly Sins themselves, believing that they can be reformed. This would involve the OC facing many challenges and having to understand the true nature of each sin.
Another interesting concept is an OC who is from a completely different dimension but gets drawn into the Trinity Seven world. This OC could have a different set of values and magic rules from their own dimension, which would create a lot of interesting interactions and conflicts with the existing characters.
A mysterious stranger from a foreign land with unique magical powers. Maybe he can control the elements to some extent. He could be initially reluctant to get involved in the group's affairs but is eventually drawn in by their sense of justice and the need to fight against a common evil.
A plot could revolve around a time - travel fanfiction. Maybe a character goes back in time and has to prevent an event that would have a catastrophic effect on the future of the Trinity Seven world. This could involve interacting with younger versions of the characters and changing their fates.
One interesting fanfiction could be about an alternate ending where one of the characters survives a seemingly fatal situation. It gives a different perspective on the story's conclusion.
One plot idea could be that the OC is a traveler who stumbles upon Okamisan and her companions in a magical forest. The OC has a special power that is needed to save the forest from a dark curse, and through their adventures together, a deep bond forms between the OC and Okamisan.
One plot idea could be that the male OC discovers a hidden power within the Trinity Seven world that no one else knew about. This could lead to a race among different factions to either control or destroy this power. Another idea is that the OC has a connection to an ancient prophecy that involves the Trinity Seven characters. As he tries to figure out his role in the prophecy, he forms closer bonds with the group.