One possible plot could be Naruto and his friends being summoned to the world of For Honor. Naruto, with his ninja skills, could team up with the samurai and Vikings in For Honor. He might teach them some of his unique jutsu, like the Shadow Clone Jutsu to create diversions in battles. And in return, he could learn the combat styles of the For Honor warriors. They could then face a common enemy that threatens both the ninja world and the For Honor world.
The plot could involve a powerful enemy in the For Honor world that the native factions can't defeat. So they somehow manage to summon Naruto characters. Sakura, with her medical and combat skills, could be a valuable asset. She could heal the wounded For Honor soldiers and also fight on the front lines. The Naruto characters would have to adapt to the new weapons and battle tactics in For Honor while also teaching their own ninja ways. This would lead to a lot of interesting interactions, battles, and a unique blend of the two universes' cultures.
I think Naruto and Kakashi would be very interesting characters to include. Naruto's raw power and ability to make friends easily could help bridge the gap between the two universes. Kakashi, with his Sharingan and vast combat experience, could analyze the fighting styles of the For Honor characters quickly. On the For Honor side, the Orochi would be fascinating. His quick and acrobatic fighting style could be compared and contrasted with the ninja's. And the Valkyrie, with her spear - based combat and female empowerment, could have some great interactions with the female ninja characters in Naruto.
Sasuke could be a great addition. He has a dark and brooding personality which would contrast well with the For Honor characters. His Rinnegan and Sharingan abilities would make him a formidable foe in the For Honor world. He could also be on a journey of self - discovery in this new universe, trying to find his place among the knights, vikings, and samurai.
One common theme is the clash of different combat styles. For example, when For Honor characters cross over with characters from other fighting - based games or universes, like Street Fighter. The different ways of fighting, such as For Honor's more medieval - style combat and Street Fighter's flashy martial arts moves, create interesting interactions.
One idea could be to have Apollyon cross over into a different time period within the For Honor universe. Maybe she finds herself in a more peaceful era and has to decide whether to disrupt it or adapt. Another could be a crossover with a character from another game where she has to battle for supremacy in a new and unfamiliar land.
First, you need to know both universes well. Research the characters, their abilities, and the worlds of Naruto and For Honor. Then, come up with a unique plot. Maybe it could be about a Naruto character getting transported to the For Honor world. Keep the personalities of the characters true to their original forms.
In a Naruto - For Honor fanfiction, the Akatsuki members could be a part of the story. They could form a sort of mercenary group within the For Honor world. Their unique abilities and personalities would make for interesting interactions with the native For Honor characters, like the Samurai and Vikings.
One idea could be that Jinx somehow gets transported to the Naruto universe. She might initially be seen as a strange and powerful figure. Naruto, being the curious and friendly type, would approach her. Jinx could then start causing chaos in the Hidden Leaf Village, which Naruto has to deal with while also trying to understand her. And they could gradually form an unlikely friendship as they learn from each other's worlds.
A different approach could be that characters from the Matrix world are brought into the Naruto universe. Trinity could learn some ninja techniques from the Konoha ninja. The Matrix characters would be amazed at the concept of chakra and how it can be used for various powers, like walking on walls or creating fireballs.