One idea could be exploring the backstories of the characters more in - depth. For example, you could write about how the main character got involved in the 'Yami no Game' in the first place. What events led them to this strange and dangerous game? Another idea is to create new challenges or levels within the game. Maybe a level that is based on a character's worst fear or a place from their past. This could add a new layer of intrigue to the story.
Another interesting concept could be a crossover fanfiction. Picture a situation where Luffy from One Piece, who has the Yami Yami no Mi in his world, somehow ends up in the Naruto world. This could lead to all sorts of chaos and interesting interactions as the two different power systems collide.
One plot idea could be Yami going on a solo mission to a mysterious and dangerous land. He has to face powerful new enemies and discover secrets about his own past. Another could be Yami training a young and inexperienced magic knight, sharing his unique combat and magic knowledge.
One idea could be exploring how the other characters react to Yami being pregnant. Maybe they are shocked at first but then become very protective. Another idea is to focus on Yami's journey through the pregnancy, dealing with the physical and emotional changes.
One idea could be a crossover with a modern - day detective story. Yami Sukehiro could use his magic and combat skills to solve mysterious crimes in a big city. Another could be a crossover with a fantasy world where he has to adapt to new magical systems and form alliances with local heroes to fight a common evil.
One idea could be exploring how Yugi and Yami's relationship deepens during the pregnancy. Maybe they face challenges together like dealing with the reactions of their friends. Another could be the magical aspects of the mpreg in the context of their world, like how the pregnancy might be connected to the powers of the Millennium Items.
Maybe a fanfiction where Yami loses her memory and Rito has to help her remember who she is. Along the way, he discovers new sides of her personality that he hadn't noticed before. It could be a sweet and emotional story as Rito tries to protect Yami while she is in this vulnerable state.
A possible plot could be that Yugi and Yami are under the influence of a love - inducing spell. They initially resist it but then give in to the feeling and kiss. Later, they have to figure out if their feelings are real or just because of the spell. Another idea is that Yami is about to be sent back to his own realm forever, and in a heart - wrenching goodbye, they share a kiss. And then there could be a plot where they are in a masquerade ball - like event in the Duel Monsters world, and not knowing each other's identities at first, they share a passionate kiss which then leads to a whole new exploration of their relationship when they find out who they really kissed.
Well, perhaps the Yami Goddess has the ability to see into Naruto's future. She warns him about a great danger that is coming, but in order to avoid it, Naruto has to learn a special technique from her. This could lead to a series of adventures where Naruto trains under her guidance while also getting to know her better and a unique relationship developing between them.
A plot idea could be that Charlotte is secretly in love with Yami but is too shy to admit it. She tries to show her feelings through her actions, like making him special treats or always being there to heal his wounds after a battle. Yami, being rather oblivious, doesn't notice at first. But as time goes on, he starts to realize there's something more to her actions. This could lead to a sweet and slow - burn romantic fanfiction.
One interesting yami no game fanfic could be about the main character's unexpected alliance in the game world. For example, they might team up with a former enemy to face a greater threat.