Well, it could be that Naruto discovers an ancient artifact that contains Hashirama's chakra. When he touches it or unlocks its power in some way, the chakra gets transferred to him. For example, the artifact might be hidden in a secret location and Naruto stumbles upon it during one of his adventures.
He might gain the ability to control wood - style jutsu more effectively. Since Hashirama was known for his powerful wood - style, Naruto could use it to create huge forests for defense or to trap enemies. For instance, he could grow trees instantly to block incoming attacks.
The addition of Hashirama's chakra to Naruto in the fanfiction would be a game - changer for his abilities. Firstly, his stamina would likely skyrocket. Hashirama was able to fight for long periods without tiring, and Naruto could inherit this. Secondly, his sensory abilities might improve. Hashirama had a good sense of his surroundings, and Naruto could use this to detect enemies from a greater distance. Thirdly, his rasengan and other chakra - based attacks could be infused with the unique properties of Hashirama's chakra, making them more powerful and perhaps having additional effects like being able to break through stronger defenses more easily.
In the Naruto fanfiction with Naruto having Hashirama's chakra, there are several potential plot developments. Firstly, Naruto could use the chakra to revive some of Hashirama's old techniques and use them to fight against a new, powerful enemy. This would involve a lot of training and exploration of Hashirama's memories that might be stored within the chakra. Secondly, the chakra could attract the attention of ancient entities or clans that were once associated with Hashirama. They could either help or hinder Naruto depending on their motives. Thirdly, Naruto might have to deal with the psychological impact of having such a powerful and different type of chakra. This could lead to internal struggles as he tries to balance his own identity with the new power he has acquired.
He might obtain it through a special encounter. For instance, he could stumble upon an ancient dragon's lair where the chakra is stored and it bonds with him.
Perhaps Naruto inherits the Rainbow Chakra. It could be a long - lost power that was once held by an ancestor. Through a series of events, like uncovering a hidden family heirloom or a secret scroll, he discovers his connection to this special chakra and learns how to unlock and use it. This would add a whole new layer to his character, as he now has a responsibility to uphold the legacy of this powerful chakra.
In some fanfictions, Naruto might use a powerful jutsu. Maybe he discovers an ancient sealing technique that can bring back the dead for a short time. He could also have found some rare chakra-infused artifact that has the power to revive the First Hokage.
Naruto's chakra mastery affects his relationships in multiple ways. In his friendship with Shikamaru, his chakra control allows him to keep up with Shikamaru's strategic plans during battles. This makes their teamwork seamless. With Hinata, Naruto's powerful chakra makes him more of a hero in her eyes. His chakra also gives him the ability to sense when Hinata is in danger and come to her rescue. Among the villagers, his chakra mastery earns him more respect, which changes the way they interact with him from being skeptical to being admiring.
Perhaps there is an ancient artifact or a powerful curse that causes Naruto to absorb all chakra. In the fanfiction world, it's common to introduce such unique elements. For example, he might find a magical scroll that, when opened, starts sucking in all the chakra in the vicinity and then channels it into Naruto. Or it could be a curse placed on him by an enemy, but instead of harming him, it gives him this strange power to absorb all chakra.
Naruto's positive attitude and his belief in friendship might make Hashirama more open - minded. For example, if Hashirama was hesitant about an alliance, Naruto could convince him with his own experiences of forming bonds across clans.
Naruto unlocking chakra chains could be a turning point in the fanfiction's plot. It could mean that he has a connection to some hidden or forgotten part of his heritage. This new power could attract the attention of the villains in the story. They might see him as a greater threat or as a valuable asset to their own plans. Consequently, the whole story could shift from Naruto being on the defensive to him being actively hunted or courted, which would be a major plot shift.