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.
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.
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.
First, make sure their personalities complement each other. Ventus is kind - hearted and brave. So, if the OC is more cautious and analytical, they can balance each other out. For example, Ventus might rush into a fight, and the OC can stop him and think of a better strategy.
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.
One great female Ventus fanfiction is 'Ventus's New Path'. It explores Ventus in a unique way as a female character, with her forming new friendships in the Kingdom Hearts universe. It has a really interesting plot that focuses on her growth and how she overcomes challenges.
One common theme is self - discovery. Since the OCs are new to the Kingdom Hearts world, they often have to figure out who they are and what their place is. Another theme is friendship, as they usually team up with the main characters from the game and form bonds. Adventure is also a big theme, as they travel through different Disney - inspired worlds.
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.