Well, Naruto might use the Keyblade to gain power and respect. He could start training with it and show those who neglected him what he's capable of.
Perhaps Naruto, with the Keyblade, will go on a journey of self - discovery. He has been neglected for so long that he might not fully understand his own potential. The Keyblade could be a tool that helps him explore his powers, both physical and mental. He may also use it to uncover secrets about his past and the world around him, and in the process, he'll become a stronger and more confident person.
In this fanfiction, Naruto could use the Keyblade to form new alliances. Since he was neglected, he might be more cautious in choosing his allies. He could use the unique abilities of the Keyblade to protect his new friends and fight against common enemies.
The people who previously neglected Naruto could become his enemies. They might see his new - found power with the Keyblade as a threat.
Well, he'd probably be an even more powerful force. The Keyblade has its own unique powers and abilities. Naruto's already strong ninja skills combined with the Keyblade could make him nearly unbeatable. He might use it in combat in ways similar to how he uses his ninja tools, but with added magical elements. For example, he could use his chakra to enhance the Keyblade's attacks.
He would probably face a lot of challenges at first. Since he's been neglected, he might not have the proper training to handle the Zanpakuto right away. But as he learns, he could start to gain respect from those who once neglected him. His new power would change the way people view him in the Naruto universe.
Well, perhaps Naruto could discover the Keyblade in a hidden realm within the Naruto world. He's neglected it because no one around him knows what it is. Then he has to figure out its powers on his own, like how to use it for combat or to unlock special portals.
Maybe Orochimaru. He could sense the power of the Keyblade and wants to take it for himself. He would see Naruto as an easy target to steal it from since Naruto doesn't really understand its value at first.
Naruto could gain the ability to manipulate light and darkness, which are often associated with Keyblades. This would be a huge change from his normal chakra - based abilities. He could also use the Keyblade to fly, giving him an advantage in both mobility and combat. Another new ability might be the power to heal, as some Keyblades have restorative properties.
In this kind of fanfiction, the Keyblade could be a key (no pun intended) to unlocking new powers within Naruto. It could be linked to some ancient prophecy in the Naruto world. Maybe it was hidden there for a long time and only Naruto, with his unique spirit, can wield it properly. This could lead to a whole new arc in the Naruto story where he has to master the Keyblade while still dealing with his ninja duties.
In a 'naruto gets captured' fanfiction, he might be tortured for information. His captors could be after the secrets of his Nine - Tails chakra. They may try to use him as a bargaining chip against Konoha.
Well, Naruto could gain the ability to use Kamui and use it for various things. Maybe he'd use it to surprise his enemies in battle, suddenly disappearing and reappearing in unexpected places. He could also use it to rescue comrades who are in dangerous situations that are hard to reach normally.
One possibility is that Naruto discovers a new level of relaxation he didn't know before. He's always on the go as a ninja, so the massage might open his eyes to the importance of taking a break.