Naruto's character would likely become more serious. The burden of his new heritage as Sparda's son would force him to grow up faster. He might not be as carefree as before.
Naruto's character would develop a new sense of purpose. Instead of just aiming to be Hokage, he would also have the goal of living up to his father Sparda's name. He would explore the meaning of his new powers and how they can be used for good. His relationships with characters like Sasuke would be affected. Sasuke might see Naruto as an even greater rival now that he has such powerful demonic abilities. And Naruto would have to decide how much of his new identity he wants to share with his friends and the village.
He would become more confident in his abilities. Since Sparda was such a powerful figure, Naruto, as his son, would know he has great potential. This new - found confidence could also make him a bit more reckless at times, as he might overestimate his new powers. He would also have to deal with the isolation that could come from being different from the other ninjas in Konoha due to his demonic heritage.
His character would become more complex. He'd be more confident in his abilities, not just relying on his magic but also on his Sparda - given powers. He might be a bit more of a loner, as he tries to understand his unique identity. Harry would also be more fearless, knowing he has the strength of Sparda in him. This could lead to him taking more risks in his battles against the dark arts.
His character could become more serious. Since Creepypasta is full of dark and spooky elements, Naruto might lose some of his naivete. He'd be more aware of the potential threats that lurk in the shadows, both in the real ninja world and in the world of his newfound interest.
His character would develop in many ways. Firstly, his physical strength and endurance would skyrocket. He'd be used to Spartan training which is extremely harsh. Emotionally, he might become more reserved as Spartans don't show emotions as openly as ninjas. His relationships would change too. His friends might see him as a different person, but Naruto would still hold onto his core values of protecting his loved ones. He could bring Spartan values like loyalty and courage in a new and extreme way to the ninja world, influencing those around him to be more like Spartans in terms of their fighting spirit and tenacity.
Naruto's sense of identity would be challenged. He was known as the hero of Konoha, but as a ronin, he is an outsider. This could make him more introspective. He might question his past actions and beliefs. He could also become more empathetic towards those who have been marginalized in the ninja world, as he now shares a similar experience.
Naruto's character would likely become more solitary as necromancy is not a common or well - liked art. He'd have to hide his new power at first. As he gets more used to it, he might become more brooding and less of the carefree Naruto we know, constantly thinking about the balance between life and death.
His character would become more open - minded. Naruto is already adventurous, but Bakugan would expose him to a completely different kind of world. He would learn new strategies and ways of thinking from Bakugan battles, which would make him a more well - rounded fighter in both ninja and Bakugan battles.
If Naruto becomes the Kyuubi in the fanfiction, his character development would be a wild ride. He'd start as a regular boy with big dreams, but once he becomes the Kyuubi, he has to face a whole new set of challenges. He has to learn to control his new form and power. This might make him more serious and less carefree as he used to be. He also has to deal with how others perceive him now. Some might fear him, some might worship him. All these things would shape his character in different ways, making him more mature and perhaps a bit more jaded.
His character would likely become more solitary. The Predator nature might make him more inclined to work alone at first. For example, he might start to go on solo missions more often. However, his loyalty to his friends would still be there deep down, and he'd gradually find a balance between his new solitary tendencies and his old social bonds.
He would become more responsible and diplomatic. Naruto as Hokage has to think about the whole village and not just his personal feelings. His impulsive nature might be toned down a bit.
His character would become more adaptable. Since Kumo is a different place, Naruto would have to quickly learn to fit in. He'd become more independent as he doesn't have his old support system from Konoha. His loyalty might be questioned at first, but as he proves himself, his new Kumo comrades would trust him.