Well, Naruto is a very energetic and positive person. If he ate the Magu Magu no mi, his personality could be influenced by the nature of the power. The magma is a very intense and destructive force. He might develop a more serious side to his personality as he realizes the potential harm his new power could cause. On the other hand, he could also use his newfound power to be more confident and inspiring to those around him. He would have to balance his normal exuberant self with the new responsibilities that come with the Magu Magu no mi powers.
Naruto's personality could change in several ways. He has always been determined, but now with the magma - related powers, he might become more assertive. He could also be more protective, seeing his new powers as a way to safeguard his friends and village even more. However, he might also face some inner struggles. The power of the Magu Magu no mi could make him feel different from his comrades, and he might have to deal with feelings of isolation at times.
Naruto would become more cautious around water. Since Devil Fruit users lose their ability to swim, Naruto, who is usually fearless, would have to be more careful near large bodies of water. This would be a big change as he often doesn't think twice about jumping into water during battles or training.
I think Sasuke would be really interesting. He already has a dark and brooding personality, and adding the power of the Magu Magu no Mi would make him even more formidable. He could use the magma to enhance his sword attacks, creating a molten blade or use it to create traps for his enemies. His Sharingan could also be used in combination with the magma powers to anticipate his opponents' moves better and launch more precise attacks.
One possible plot could be a character from the Naruto world obtaining the Magu Magu no Mi. They could then use the powers of the fruit, like creating and controlling magma, in battles against the Akatsuki. For example, imagine Naruto with the Magu Magu no Mi powers facing off against Sasuke. Naruto could use the magma to create barriers or launch powerful attacks, adding a new dimension to their rivalry.
The OC could also be a very protective type. Since fire can be seen as a symbol of protection in some ways, they would use their Magu Magu no mi powers to safeguard their friends and family. They might be calm and collected most of the time but when danger approaches those they care about, their personality shifts to a more fierce and determined state. They would create barriers of fire around their loved ones and face the threat head - on.
The plot could involve Naruto sharing his new power with his friends in Konoha. He could teach them how to work with the fire - based powers of the Magu Magu no mi. They could then develop new strategies for battles. For instance, Sakura could use her superhuman strength in combination with Naruto's new fire attacks to create a more powerful defense and offense for the village. Also, Naruto might have to hide his new power from some of the more traditional shinobi in the village who might be suspicious of this foreign power source.
He would likely be more isolated at first. The Magu Magu Fruit powers are different from normal ninjutsu. His friends might not understand it fully, and he would need time to master it alone. This would make him more introspective, but as he gets better control, he would start to share his knowledge and use it for the good of the village. Also, his fighting style would change drastically. Instead of relying solely on his shadow clones and Rasengan, he would incorporate the heat - based attacks of the Magu Magu Fruit, making him a more versatile fighter.
One idea could be a story where a young pirate discovers the Oca ate Magu Magu no Mi. They struggle at first to control the power of the fruit but gradually learn to master it. They use the powers to protect their crew from a powerful enemy.
Another place to look could be Naruto - dedicated forums. There are often sections where fans share their own fanfiction creations or recommend stories they've read. Some of these might include Magu Magu - themed fanfictions. You just need to do a bit of digging around in the different threads.
One interesting Naruto Magu Magu fanfiction could be about a new jutsu that combines the power of Magu Magu with another element in the Naruto universe. For example, a story where a character discovers how to merge Magu Magu with lightning to create a super - powerful attack. This would not only change the dynamics of battles but also the character's standing in the ninja world.
In a fanfiction, the Oca ate Magu Magu no Mi might grant the ability to fly by creating a platform of fire beneath the user. This would add an extra dimension to the battles and the overall story. Also, the user could be immune to heat - based attacks from other sources, which would give them an edge in a world full of various powers.