In the fanfiction world, the author might create a backstory where Samehada has a pre - existing connection to Naruto that was dormant until now. For example, Naruto could be related to an ancient shinobi that Samehada was once bonded with, and this latent connection causes Samehada to leave Kisame in order to be with Naruto.
Perhaps Naruto has a different fighting style that Samehada finds more appealing. Naruto is known for his unpredictable and energetic combat, and Samehada might be drawn to that. It could also be that Naruto has a certain charisma or willpower that Samehada responds to on a more instinctual level.
Kisame would probably be very angry at first. Samehada is his weapon and has been with him for a long time. He might feel betrayed and try to get Samehada back by force.
In the fanfiction, it could be that Kisame gives Naruto Samehada as part of a deal. Maybe Naruto has to do something for Kisame in return. Naruto might struggle with the idea of making a deal with an Akatsuki member but decides it's worth it for the power of Samehada. Once he has it, he might face opposition from his friends and village elders who are suspicious of his new weapon and the way he obtained it.
The plot could involve Naruto using Samehada to gain an understanding of the Akatsuki's motives. Since Samehada has a connection to the Akatsuki through Kisame, it might hold some secrets. Naruto could use it to track down other Akatsuki members or find out more about their plans.
Another way is that Samehada might be given to Naruto by a mysterious figure. This figure recognizes Naruto's potential and believes that he can handle the power of Samehada. This then sets off a chain of events where Naruto has to learn about and master Samehada's abilities.
Well, it could be about Samehada being overlooked in the Naruto universe. Maybe it's not being used to its full potential. For example, it might be that no one realizes its unique abilities aside from just being a weapon. Or perhaps it's being misused or underutilized by its owners.
Well, in 'naruto meets samehada fanfiction', Naruto could potentially have a fight with the wielder of Samehada. During the battle, he might discover some new aspects of his own powers as he tries to counter Samehada's ability to absorb chakra. And it could also lead to an unexpected alliance if they face a common enemy.
In some fanfictions, Naruto might gain the ability to absorb Samehada through a special encounter. Maybe he discovers an ancient jutsu that allows him to connect with Samehada on a spiritual level and absorb its power.
One possible plot could be that Naruto somehow gets bonded with Samehada. Maybe during a battle in an alternate dimension where the laws of chakra and weapons are all jumbled. Naruto starts to learn how to use Samehada's unique abilities, like absorbing chakra not just to power himself but also to heal. This causes a stir among the ninja world as they see Naruto with this new and somewhat menacing power - the power to drain their chakra with ease. His friends are initially cautious but then come to realize that Naruto is still the same person inside and they work together to master this new form of power.
The plot might be that an enemy steals Samehada and Naruto has to get it back. Along the way, he discovers that Samehada has a connection to an ancient and powerful clan. Naruto teams up with some members of this clan who want to reclaim Samehada as well. They face many challenges together, and Naruto uses his own skills and the power of Samehada to defeat the enemy. In the end, Naruto decides what to do with Samehada, whether to keep it or return it to the clan, depending on the bond he has formed with it.
It could be Samehada itself. Since the story is about it being neglected, it makes sense for it to be the main focus. It could have its own 'voice' and thoughts as it tries to deal with the situation.