A possible plot is that some of the characters from Naruto are experimented on by the Umbrella Corporation. Sasuke, for instance, could have his Sharingan enhanced in unexpected ways due to the unethical experiments. This would lead to a power struggle within him as he tries to control his new abilities while also dealing with the fact that he has been turned into a sort of bio - weapon. And then Naruto would have to find a way to save him without getting infected himself.
Well, there could be a story where the Konoha village is suddenly infected with a virus similar to the T - virus from Resident Evil. The ninja have to use their skills in a different way to combat the virus - affected villagers who are turning into something like zombies. At the same time, some Resident Evil characters like Leon could arrive in the Naruto world to help, bringing with them their knowledge of dealing with bio - threats and new weapons that the ninja have never seen before.
One idea could be that Naruto and his team are sent to the Resident Evil universe to find a cure for a virus that has started to infect the Hidden Leaf. They would have to face off against zombies and bio - weapons using their ninja skills. Another plot could involve a Resident Evil character getting transported to the Naruto world and having to adapt to chakra and ninja society. For example, Leon Kennedy could team up with Naruto to stop a bio - terrorist attack in Konoha.
Perhaps the T - virus from Resident Evil 4 somehow mutates some of the Naruto characters. Naruto himself could be turned into a half - human, half - virus - infected being with new and strange powers. He would then have to struggle not only with the effects of the virus but also with the fact that his friends might see him as a threat. This would add a whole new layer of drama and conflict to the fanfiction.
Well, a cool fanfiction concept could be that some of the Resident Evil villains get transported to the Naruto universe. For example, Albert Wesker shows up and tries to take over the ninja villages using his superhuman abilities and intelligence. Or perhaps the Resident Evil bio - weapons are let loose in the Naruto world and the shinobi have to figure out how to deal with these new threats that are completely different from their usual enemies like other ninja clans or rogue ninjas.
A Resident Evil and Devil May Cry crossover fanfiction could be cool. Dante from Devil May Cry could visit the Resident Evil world. His over - the - top combat skills would be a great contrast to the more survival - horror based combat in Resident Evil. He could help the Resident Evil characters fight against bio - organic threats like Nemesis or Tyrant. Also, a crossover with the Castlevania series might work. The gothic horror elements of Castlevania combined with the modern horror of Resident Evil could lead to a story about fighting vampires and bio - horrors together.
A cool fanfiction plot might be to introduce a new character who has a special ability to communicate with the infected. This character could either help Leon or create new challenges for him as he tries to rescue Ashley.
You might consider a fanfiction where the main character has the ability to communicate with the Mold, and through this connection, tries to find a way to end the cycle of horror in the village once and for all. This would involve exploring the nature of the Mold, its intelligence (if any), and how it affects the inhabitants of the village both physically and mentally.
Another interesting twist is if it turns out that some of the powerful jutsu in the Naruto world are actually the result of an ancient experiment similar to the ones in Resident Evil. For example, the Sage of Six Paths was actually trying to create a powerful being by combining natural energy with a virus - like substance, which is similar to how the Resident Evil scientists create their monsters. This revelation could change how the Naruto characters view their own powers and history.
One idea could be exploring the backstory of Lady Dimitrescu's daughters in more detail. Maybe how they came to be and their lives before Ethan Winters arrived.
One idea could be exploring the backstory of the Baker family in more detail. Maybe how they got infected in the first place and what their lives were like before the events of the game.
One idea could be exploring the backstory of the secondary characters more in - depth. For example, what was the life of the police officers in Raccoon City before the outbreak? Another could be a different take on how the main characters like Leon and Claire met and teamed up. Maybe they initially had some misunderstandings before realizing they needed to work together to survive.