A cool concept would be an OC that has the ability to see the future. They foresee a great danger that Ventus will face and try to prevent it. But in doing so, they accidentally change some events which lead to new challenges. This could create an interesting plot full of twists and turns.
One idea could be an OC who is a keyblade wielder from a long - lost world. They meet Ventus during his travels and join him on his journey to restore the balance in different worlds. This OC could have a unique keyblade design inspired by their home world's culture.
Another idea is an OC who is a healer. Ventus gets injured in a battle and the OC uses their special healing powers to save him. As a result, they form a strong bond and the OC decides to accompany Ventus in his fight against the darkness. The fanfic could explore how their relationship grows over time.
Perhaps the OC has a special power that is linked to Ventus' past in some way. For example, she can see glimpses of his forgotten memories. This leads to a journey where they explore his past together, while also growing closer and falling in love along the way. They might face challenges from Organization XIII who are interested in the OC's power.
To write a believable fanfic, you need to develop your OC's personality. Are they brave or cautious? Optimistic or pessimistic? Their personality should influence their actions and decisions. When it comes to Ventus, show how your OC's presence affects him. Maybe your OC's positive attitude helps Ventus overcome his self - doubts. And don't forget about the dialogue. It should be in - character for both the OC and Ventus.
I really like the fanfic 'Terra and Ventus: A New Beginning'. It starts with an interesting take on their first meeting. The author does an excellent job of showing their personalities - Terra's determination and Ventus's innocence. It also has some really cool action scenes that are in line with the Kingdom Hearts style.
There's a fanfic called 'Aqua's Promise to Ventus'. In this story, Aqua makes a solemn promise to Ventus during a difficult time in their journey. The fanfic is great as it shows the strength of their friendship and how they support each other through hardships. It also has some beautifully described scenes of the Kingdom Hearts world.
One great 'Kingdom Hearts Ventus x Aqua' fanfiction is 'The Bond Beyond Worlds'. It beautifully explores their relationship in a post - game scenario, with lots of emotional exchanges and adventures together.
One good one could be 'The Bond Beyond Darkness'. It really delves into the complex relationship between Ventus and Vanitas. It shows how their connection is more than just their opposing natures.
One idea could be creating an OC who is a keyblade wielder from a forgotten world. This OC could be on a quest to discover the secrets of their world's connection to the greater Kingdom Hearts universe. They might encounter classic characters like Sora and Riku and have to prove their worth as a keyblade wielder.
A good Kingdom Hearts fanfiction with female Ventus should have a strong characterization. Since Ventus is an established character in the original, the fanfic should stay true to her core traits while also exploring how being female might change her perspective. For example, her relationships with other characters like Aqua and Terra could be different in a female Ventus version.
Perhaps a fanfiction where Ventus has a premonition of a great danger that only he and Vanitas can prevent together. As they journey to stop it, they gradually form an unexpected bond. They learn that their connection is deeper than they initially thought, and this realization changes their relationship throughout the story.
Another interesting concept is an OC who is a member of an organization that opposes Organization XIII in a different way. Maybe they use magic that is not based on darkness or light, but something in between, which causes them to be shunned by both sides at first.