His confidence would likely soar. Knowing he has the speed of the Yellow Flash, Naruto would feel more capable in battle and in general. He might be a bit more cocky at times, but still retain his kind heart. For example, he could show off his speed to his friends in a friendly, competitive way.
He could become more of a leader. With the power of the Yellow Flash, Naruto would be seen as even more of a hero. This could lead to him taking on more responsibilities in the village. His personality would adapt to this new role. He would be more diplomatic, using his speed not just in combat but also to quickly resolve disputes within the village or between villages. He would also inspire others to strive for greater heights, just as the Yellow Flash once did.
His personality might become more cautious. Since he has a greater responsibility as a guardian, he can't be as reckless as he was sometimes in the original Naruto series.
His personality might become more withdrawn. As a lich, Naruto could be feared by others, and this might make him more hesitant to interact with people. He was always so outgoing before, but now he might keep to himself more.
Naruto may also become more solitary. Sparda often fought alone, and Naruto, influenced by this, might start to distance himself from his friends at first. However, he would still have that underlying loyalty and would eventually find a way to balance his new - found independence with his relationships.
His confidence would skyrocket. Gilgamesh is extremely self - assured, and Naruto, if influenced by him, would become even more so. He'd be more outspoken about his own abilities and less likely to doubt himself in tough situations.
Naruto's personality would change in several ways. He would become more aggressive, which is a big part of Wolverine's character. He might be quicker to anger and less patient. However, he would also have a sense of loyalty like Wolverine. His old self - sacrificing nature would still be there but it would be expressed in a more Wolverine - like way, being more protective and ready to fight for those he cares about without hesitation.
If Tails becomes a robot in a fanfiction, his personality might become more logical and less emotional. Since robots are often programmed to be rational, he might start to analyze situations more coldly. For example, he might not be as quick to jump into a rescue mission out of pure compassion like he used to.
His confidence might increase even more. Naruto was always confident as a ninja, but as a sorcerer, he has new powers at his disposal. He would feel even more capable of taking on challenges. For example, if he faces a powerful sorcerer enemy, instead of being intimidated, he would be eager to test his new abilities.
He might become more patient. As a medic, he has to be careful and take his time with patients, which is different from his impulsive fighting style.
If Naruto becomes involved with Slenderman in a fanfiction, his usually cheerful and determined personality might become darker. He could be more withdrawn as he grapples with the strange and often terrifying aspects of Slenderman's world.
Naruto's normally exuberant and optimistic personality might become a bit more brooding. Alex Mercer is a complex character with a lot of internal conflict due to his past and his powers. Naruto, being a fan, might start to question some of his own beliefs. He could become more reserved as he tries to understand Mercer's more solitary nature. However, he would still retain his core of kindness and loyalty to his friends, but it might be expressed in a different way. For example, instead of his usual loud declarations of friendship, he might be more quietly protective.