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 idea could be to give the necromancer OC a tragic backstory. Maybe they lost someone dear and that led them to study necromancy in a desperate attempt to bring the person back. This could shape their personality, making them more brooding and determined. Another aspect could be their moral stance on necromancy. Are they using it for good, like bringing back fallen comrades to fight against greater evil? Or are they being tempted by the dark side of this power? Also, consider their relationship with the existing RWBY characters. They might initially be feared or mistrusted, but gradually earn respect through their actions.
For character development, the mute OC might struggle with feelings of isolation at first. But as the story progresses, they could form deep bonds with other characters who learn to understand them in unique ways. For example, a character might be able to sense their emotions, leading to a really heartwarming friendship.
One idea could be to give the sister a unique power. For example, she could have the ability to control the elements, which would set her apart from Sesshomaru and Inuyasha. This power could also create interesting storylines as she might have to learn to control it.
One idea for character development could be exploring the Crow Faunus' backstory. Maybe they come from a family of outcasts within the Faunus community due to their crow features. This could lead to a sense of isolation and a drive to prove themselves. Another aspect could be their relationship with other characters in the RWBY universe. They might form an unlikely alliance with a human character who initially distrusts Faunus, but over time they learn to trust and rely on each other.
She could have unique skills that set her apart from other mercenaries. For example, she might be an expert in both combat and hacking. In the fanfiction, she could use these skills to take on dangerous missions that others wouldn't dare. Her hacking skills could also be used to uncover secrets about the various factions in the Mass Effect world.
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 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, the OC could be an outcast in her own community. When she enters the world of Inuyasha and Koga, she finds a new sense of belonging. Koga's wolf pack could initially reject her, but through her determination and kindness, she wins them over. Inuyasha's friendship also helps her to see her own worth. As the story progresses, she becomes a strong and respected figure, not just among them but also in the wider world of demons and humans they inhabit.
The character can show development through their attitude towards their new life. At first, they might be confused or even resentful of being reborn as Naruto. But as time goes on, they start to embrace the world and its values. For example, they could learn to value the concept of ninja way more deeply.
The OC would likely start as a relatively inexperienced ninja. Under Madara's tutelage, they would become more confident and skilled. For example, they might learn how to better control their chakra.