Maybe in the fanfic, Death is not a traditional Grim Reaper - like figure but rather a form of an evil curse that has been plaguing the ninja world. Naruto, being the hero, is the only one with enough positive energy and determination to face it. He could start by gathering allies who have also been affected by this 'Death' curse. Together, they form a plan. Naruto would be the vanguard, using his speed and strength to break through the defenses of the curse - based Death and then use his willpower to shatter it completely.
One possible plotline could be that Naruto fakes his death to protect the village from a powerful enemy who has a vendetta against him specifically. He might do this to draw the enemy out and expose their weaknesses.
Another plotline might be the bringer of death's journey of redemption. They start off as a cold - blooded killer but then meet someone or experience something that makes them question their ways. They could then try to use their powers for good, which would be a difficult transition as they are feared by many. This could create a lot of internal conflict within the character as well as external conflict with those who don't trust their change of heart.
Well, it could involve a plot where the wizarding world discovers Harry's immunity and tries to either use it for their own gain or tries to figure out how it happened. There could be a race between the good and the bad characters to unlock the secret of his immunity. Maybe Harry has to go on a journey to understand this strange new power within him, and along the way, he meets new allies and enemies.
A possible plotline is that a powerful villain threatens both Naruto's world and Alita's world. They are brought together by a mysterious force to stop this villain. Along the way, they face many challenges as they try to understand each other's powers and cultures. For example, Alita may not understand the concept of ninjutsu at first, and Naruto may be baffled by her mechanical body.
One possible plotline could be Naruto ending up in Alois' world and having to adapt to its different rules and power dynamics. He might use his ninja skills in unexpected ways to survive and make a name for himself.
A plotline could involve Islamic mythology or figures somehow making their way into the Naruto universe. Maybe an Islamic - inspired spirit or entity appears in the Hidden Leaf Village and has to be dealt with, and the characters learn about Islamic beliefs in the process.
A plotline for a Naruto Keyblade fanfic could start with Naruto finding a strange Keyblade - like object during one of his missions. As he tries to figure out what it is, he accidentally activates it and is sent to a different realm. In this realm, he meets other Keyblade wielders who help him understand the power of the Keyblade. Meanwhile, back in the Naruto world, his friends are worried about his disappearance and start searching for him. Naruto then has to master the Keyblade and find a way back home while also dealing with any threats in the new world.
A possible plotline could be Naruto and his friends being transported to the WW2 era. They then use their ninja skills to try and stop the war. Or perhaps they side with one of the Allied forces and help them in their battles. Another plotline could be that a powerful Naruto villain teams up with a WW2 dictator and they create chaos together. The heroes have to then find a way to defeat this unholy alliance.
One possible plotline could be her journey to overcome her blindness and prove herself as a ninja. She might have to develop her other senses more acutely, like hearing and smell, to compensate for her lack of sight. For example, she could learn to sense chakra in a different way.
One possible plotline could be Naruto somehow ending up in the Nurarihyon world and having to learn the rules and powers there. Maybe he teams up with some of the Nurarihyon characters to face a common enemy.