One possible plot twist could be Naruto having an unexpected affinity for kido, a type of spiritual magic in the Bleach universe. Since Byakuya is a master of kido, Naruto might inherit some latent ability for it. This would put him at odds with the traditional ninja arts he was taught in Konoha and lead to a whole new path of self - discovery as he tries to balance the two different power systems.
Maybe Naruto's connection to Byakuya would draw the attention of the Soul Society. They might see him as an anomaly and either try to recruit him or eliminate him. This would force Naruto to make some tough choices about which world he truly belongs to, Konoha or the Soul Society. And his friends in Konoha would be left confused and concerned about his newfound heritage and the threats it brings.
Well, in this fanfiction, there could be a plot twist where Byakuya has enemies from his world who come after Naruto. Naruto, thinking he's just an ordinary ninja, is suddenly thrust into a situation where he has to deal with these powerful and unknown foes. And as he tries to figure out his connection to Byakuya, he also has to protect himself and his friends from these new threats.
One possible plot twist could be that the pregnancy is a result of some sort of magical or spiritual interference. Maybe an enemy had a plan to create a powerful being by combining their powers through this unorthodox method. Another twist could be that Ichigo discovers she has some hidden heritage that makes the pregnancy more complicated and dangerous. It could also be that Byakuya has to face his own family's reaction to this unexpected union and pregnancy, which could lead to internal conflicts within his clan.
A plot could involve Byakuya being sent to the wizarding world on a mission. He meets Harry Potter, who is intrigued by this strange and powerful being. Harry shows Byakuya the wonders of magic, and Byakuya in turn shares his knowledge of the Soul Society. As they spend more time together, they find themselves drawn to each other. However, there are those in both worlds who see their relationship as a threat or an abomination. They have to fight against prejudice and also against an evil that wants to use their relationship for its own dark purposes.
One idea could be a crossover where Byakuya Kuchiki is somehow transported to the Naruto world. He might initially struggle with the different chakra system compared to the reiatsu he's used to in his own Bleach universe. His stoic and disciplined nature could make him an interesting character to interact with the more exuberant Naruto characters.
Perhaps a plot twist is that Naruto's true parentage was hidden because there was a prophecy about him being a threat to the current ninja order. Mikoto and Minato had to keep it a secret to protect Naruto from being killed as a child. But as Naruto grows stronger and starts to show signs of his powerful bloodline, those who fear the prophecy start to target him again. This would force Naruto to not only prove himself but also fight against the unjust system that wants to eliminate him based on a baseless fear.
Perhaps Naruto discovers that his parents' relationship was part of a larger, more secretive plan in the shinobi world. Maybe there was an ancient prophecy that led to Minato and Mikoto getting together to produce Naruto, who is destined for a special role. This could involve Naruto having to face some difficult choices about his identity and purpose. He might have to decide whether to follow the path laid out by this prophecy or create his own.
A plot twist could also involve Naruto's relationship with the Uchiha clan. Since he's the son of Hitomi Uchiha, he might face different challenges within the clan. They could be hesitant to accept him at first because of his Uzumaki heritage, but then come to realize his value as he shows off his Uchiha - like abilities.
One possible plot could be Naruto growing up in the Bleach universe with the skills and powers of both his parents. He might struggle to fit in at first due to his unique heritage. Maybe he has to prove himself in the Soul Society while also having some Naruto - like determination.
With Kakashi, Naruto's relationship might shift. Kakashi would be intrigued by Naruto's newfound connection to Byakuya Kuchiki. He would have to adjust his training methods to incorporate Naruto's emerging Shinigami - like abilities. Naruto might also start to see Kakashi more as a guide in this new world of the unknown that his heritage has opened up.
Another characteristic often explored in fanfiction is his power. His swordsmanship and his zanpakuto's abilities are sometimes elaborated on in ways that go beyond what was shown in the original anime or manga. Fanfic writers might create new battles or training scenarios for Byakuya to show off his strength and skill, while also delving into how his power affects his relationships with others, either through envy, respect, or fear.