Another plot device is the mystery surrounding the origin of the demon arm. In many fanfictions, the arm's origin is not clear at first. It could be related to an ancient curse, a long - forgotten experiment, or a connection to a powerful and malevolent being from Naruto's world's past. Writers use this mystery to keep readers hooked as Naruto tries to uncover the truth about his arm.
There is a fanfiction where Naruto gets a demon arm after a strange encounter in an ancient temple. The story delves into how he has to hide this new appendage from his friends at first because he doesn't understand it himself. It also has great action scenes where he learns to fight with the added strength and abilities the demon arm provides. Overall, it's a unique take on the Naruto universe.
Sasuke could be a candidate. Given their complex relationship, Sasuke might find a way to give Naruto a new arm as a way to atone for their past differences. He could have discovered some rare medical ninjutsu during his travels or come across a powerful artifact that he uses to create a new arm for Naruto.
Maybe Orochimaru. Despite being a villain in the past, he is a master of forbidden jutsus and experiments. He could see Naruto as an interesting subject and give him a new arm with some dark powers, which Naruto would then have to learn to control for the greater good.
Well, it could be that he got it as a gift from some super - advanced ninja technology group in the fanfiction world. Maybe they saw his need for an extra weapon or tool during battles and decided to equip him with a metal arm.
One special ability could be enhanced strength. The metal arm might be able to deliver much more powerful punches than his normal arm, allowing him to break through tough defenses more easily.
One common plot point could be the character with the demon arm struggling with its power. For example, they might have a hard time controlling it during battles, which could lead to some unexpected and dangerous situations. Another plot point could be the origin of the demon arm. Maybe it was a curse from an ancient evil or a result of some forbidden jutsu experiment. Also, the demon arm might attract other dark forces, creating more conflicts in the story as the character has to deal with not only the arm's power but also those who seek to use it for their own malicious purposes.
Maybe he was protecting someone in Wave. He's always the self - sacrificing type, so he could have put himself in harm's way to save a villager or a friend.
One possible fanfiction could be about Naruto's right arm gaining a new and mysterious power. Maybe it starts to glow with an unknown chakra, and he has to figure out how to control it without losing himself. It could be a power that has a connection to an ancient ninja clan's secret technique.
Well, in some fanfictions, he might get it from a skilled ninja prosthetics maker. This maker could be someone who specializes in creating artificial limbs for ninjas who have lost their arms in battle.