He would likely become more irreverent. Naruto is usually quite earnest and determined, but as Deadpool, he'd be cracking jokes all the time, even in serious situations. With Fem Kyuubi around, he might tease her constantly. For example, he could make fun of her tails or her sometimes - haughty attitude. His sense of morality might also shift a bit, becoming more in line with Deadpool's grey - area ethics.
Naruto's personality would become more self - aware in a meta - sense. Deadpool is famous for breaking the fourth wall, and Naruto in this scenario would probably do the same. He'd be aware that he's in a fanfiction and might make references to it. In relation to Fem Kyuubi, he could be more flirty and less shy compared to his original self. He might also be more willing to take risks, not just in combat but also in his relationship with her, without the usual hesitations Naruto had in the original series.
His personality would become much more irreverent. He'd be making sarcastic remarks left and right. For example, when facing an enemy, instead of the usual Naruto pep talk, he'd say something like 'Oh look, another bad guy. How original.'. He'd also be more self - aware, like Deadpool, and might comment on the absurdity of the Naruto plot sometimes.
His personality could become more irreverent. Naruto is typically respectful of his elders and the ninja hierarchy, but Deadpool's influence might make him question and joke about those things more.
Well, Naruto's personality would have an interesting transformation. He would likely become more of a risk - taker. The pirate world is full of uncertainties and dangers, and Naruto would embrace this. He might become more laid - back in some ways, enjoying the simple pleasures of life at sea like drinking grog (if they have something similar in this fanfiction world) and singing sea shanties. But at the same time, his competitive nature would still be there. He'd want to prove himself as a great pirate, perhaps competing with other well - known pirates. His naivete might also change a bit. While he was often naive in the ninja world, the harshness of the pirate life would make him more street - smart, yet still retain his positive outlook on life.
His relationship with his friends would be very different. His old friends might be confused and a bit scared of him at first. They were used to the normal Naruto, and now he's this Joker - like figure. With the Fem Kyuubi, his relationship would be based on mutual understanding of their unique states. The Fem Kyuubi may be one of the few who can truly understand Naruto in his new form.
He might become more brooding. The new powers and the vampiric nature could make him a bit more withdrawn as he tries to understand and control his abilities. But his core of kindness would still be there.
His confidence would likely soar. Naruto has always been confident, but as the Sorcerer Supreme, he'd have an even greater sense of self - assurance. He'd know he has the power to protect and make a difference on a much larger scale. He might also become more reserved in some ways, as he'd have to deal with more serious magical matters and might not be as quick to jump into action without thinking first.
Naruto's personality could become more complex. He was always an optimist as a ninja, but as a shinigami, he might see the darker side of things more often. However, his core values of friendship and protecting others would remain. He might be a bit more reserved in expressing his emotions as the shinigami world may have different social norms. But overall, he'd still be the same Naruto at heart, just with a different perspective on life and death.
He might become more patient. Blacksmithing requires a great deal of patience, and this could seep into his personality. He would have to be meticulous in his work, which could make him more detail - oriented in his interactions with others as well.
His already positive personality would become even more so. He'd be like a beacon of hope. He might be more focused on bringing out the best in others, since that's what Blue Lanterns do.
His power level would skyrocket. Naruto already had the power of the Kyuubi within him, but as a kitsune, he'd have a more direct connection to that power. He could access it more easily and use it in ways he couldn't before. For instance, he might be able to transform into a full - kitsune form with ease, and in that form, his speed, strength, and durability would be greatly enhanced.