One aspect of Naruto's character development could be his relationship with other Batman characters. He might have a sibling - like relationship with Robin. They could train together, with Naruto teaching Robin some ninja techniques. With Alfred, Naruto could learn about more refined manners and also get help in developing his detective skills. And in terms of his relationship with the villains, he might try to redeem some of them like he did with some of his enemies in the Naruto world, which would be a huge contrast to Batman's more straightforward approach of just stopping them.
Naruto could develop a darker side. Growing up with Batman, he'd be exposed to Gotham's crime and corruption early. But his Naruto - like spirit would still shine through. He might start using Batman's gadgets more efficiently than Bruce himself, adding a new dimension to his fighting style. For example, using smoke bombs in a more ninja - like way during battles.
For character development, Naruto would have to balance his ninja values with Batman's no - killing rule. He might struggle with this as in his own world, he's more used to fighting to the death in some cases. Also, he could learn to be more of a loner like Batman, but still maintain his friendly and outgoing nature with the people he trusts. This could lead to some interesting internal conflicts as he tries to fit into both the ninja world and Gotham's vigilante scene.
One idea could be to make the OC a healer. Since Naruto often gets into dangerous battles, a mother - like OC who can heal his wounds would add an interesting dynamic. The OC could have learned healing jutsu from a hidden clan. Another idea is to give the OC a tragic backstory, like losing her family in the war, which makes her protective of Naruto as she sees in him the hope for a better future.
One possible character could be Rock Lee. If he had a metal arm, it could enhance his taijutsu. Maybe he got it after a dangerous mission where he lost his original arm. He could use the metal arm to deliver more powerful punches and even incorporate some unique techniques. For example, he could attach weights or blades to it for different combat situations.
Naruto's character would change a lot. He'd become more reserved perhaps, as Sesshomaru is a rather aloof character. But he'd also have a new sense of power and pride. His development could involve learning to control his new demon powers, which might be more difficult than his chakra control. He might start to view the world from a more demon - like perspective, seeing things in terms of power hierarchies more often.
Naruto would likely be more confident from the start. Knowing he is the son of Hashirama, a great Hokage, would give him a sense of self - worth that he initially lacked in the original series. He might not be as much of an outcast, or at least he would have a different kind of status in the village.
If Naruto is the son of Kyuubi in the fanfiction, his character development would be drastically different. He would have a different kind of self - discovery journey. His relationship with the villagers could be more hostile from the start. They might not just see him as the container of the Kyuubi but as the actual offspring of the beast they fear. This would force him to grow up faster, in a sense. He would have to prove himself not just as a ninja but as someone worthy of acceptance despite his 'parentage'. His training might also focus more on controlling his in - born Kyuubi - like traits rather than just taming the Kyuubi's power within him.
Since Kakashi has his own set of friends and allies, Naruto would be exposed to a different social circle. This could lead to different relationships and interactions that shape his character. For example, he might have a closer relationship with Gai or Asuma in this fanfiction. Their influence, combined with Kakashi's parenting, would make Naruto more well - rounded and perhaps more in - tune with the overall shinobi community.
In a Naruto - Batman Beyond fanfiction, perhaps there could be a crossover of technology and ninjutsu. The high - tech gadgets in Batman Beyond's world could be combined with Naruto's chakra - based abilities. For instance, a bat -arang infused with chakra for added power.
Another concept could be a fusion of their powers. What if Terry McGinnis got some of Naruto's chakra and was able to use it in his Batsuit? He could enhance his strength, speed, and agility even more. Maybe he could also use Naruto's Rasengan technique in a modified form to take down enemies. It would be really cool to see how the technology of the Batman Beyond world and Naruto's ninja abilities would interact.
Naruto's character would likely become more complex. He'd have to grapple with the new identity of being the son of a famous pirate. He might start to question his ninja values and consider more pirate - like ways of thinking, like freedom and adventure in a different light.
Naruto might be more confident from the start. Since he's the son of two respected shinobi, he could have a different self - image compared to canon Naruto. He might not have the same insecurities about being an orphan or not being good enough.