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.
Naruto's Rasengan could be used in interesting ways. For example, if he combines it with the Resident Evil knowledge of bio - energy, he might be able to create a Rasengan that can destroy the mutated cells of the bio - weapons more effectively. And for characters like Chris Redfield, his combat skills and experience with firearms could be enhanced by learning some basic ninja moves from the Naruto characters, like how to move stealthily.
Survival is also a big theme. Just like in Resident Evil, characters from both universes have to find ways to survive in a new and dangerous situation. For instance, Naruto characters may have to deal with the bio - weapons and traps of the Resident Evil world. Inversely, Resident Evil characters might struggle to survive in a world full of ninjas with superhuman abilities.
Another idea is that the T - virus from Resident Evil gets into the Naruto universe. Konoha village is suddenly faced with an outbreak of zombified villagers. The ninja have to figure out how to stop the spread of the virus. Maybe some of the Resident Evil characters like Leon or Claire are also brought into the Naruto world to help. They could teach the ninja about the nature of the T - virus and how to combat it with modern weapons and strategies.
Sasuke's sharingan would be a very useful ability in the Resident Evil world. He could use it to quickly analyze the movements and weaknesses of the mutated creatures. In return, Resident Evil characters could teach the Naruto characters about modern weaponry. For instance, Ada Wong could show Sakura how to use a grappling hook gun, which Sakura could then incorporate into her combat style along with her medical ninjutsu. Also, Naruto's rasengan could be enhanced with some Resident Evil technology, like using a virus sample to make it more deadly against bio - enemies.
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.
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.
Survival is a very common theme. Just like in the original Resident Evil 7, characters in crossovers are often faced with life - threatening situations. They have to find ways to stay alive in the face of the various horrors, whether it's the Molded or the threats from the other franchise in the crossover.
One possibility could be that Alex Mercer's powers disrupt the normal horror elements in Resident Evil 7. His shape - shifting ability might give him an edge against the Molded enemies. For example, he could blend in with the environment to surprise them.
Survival is a common theme. Whether it's crossing over with another survival - horror franchise or a more action - oriented one, the characters are often faced with new threats and have to find ways to stay alive in the Resident Evil 5 crossover fanfiction. For example, when crossed with a post - apocalyptic world like in Fallout, they need to find resources and shelter while fighting off the Resident Evil enemies.