The plot might also revolve around a mystery. Suppose there's a strange phenomenon occurring that seems to be related to their powers or their pasts. Ichigo, Byakuya and Stark might have to team up to solve this mystery. They could travel to different realms in search of clues. Along the way, they could have some interesting interactions. For example, Byakuya could be initially reluctant to cooperate with Stark because he is an Arrancar, but Ichigo could act as a mediator, trying to get them to put aside their differences for the greater good.
Yhwach could also be a main antagonist. He has grand plans for the world and his power to absorb and manipulate souls is a huge threat. He would see Ichigo, Byakuya and Stark as obstacles in his way. His army of Quincy could also pose a significant challenge to our trio, and his very existence challenges the balance of power in the Bleach universe.
A plot twist might be that Ichigo discovers some long - hidden family secret related to Byakuya during their marriage preparations. This secret could change the way he views Byakuya and their relationship, adding a layer of complexity and drama to the story. For example, it could be related to a past event that involved their ancestors.
In a 'Byakuya meets Ichigo' fanfiction, they might start as rivals and gradually develop respect for each other. Maybe they'll team up to fight a common enemy. For example, a powerful Hollows that neither could defeat alone.
One possible plot could be that Byakuya has been secretly watching over Ichigo all his life. He could use his influence in the Soul Society to protect Ichigo from afar, while Ichigo has no idea of their relation. Eventually, the truth could be revealed during a major battle when Byakuya steps in to save Ichigo in a way that makes it obvious they are related.
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.
Perhaps Byakuya loses his powers and Ichigo has to help him regain them. This role - reversal would be very interesting as Ichigo becomes the teacher and Byakuya the student. They would have to work together in a whole new way, and Ichigo would have to prove himself to Byakuya in a different context.
Well, it could start with an unexpected event that leads to the pregnancy. Maybe some sort of magical or unforeseen circumstance. Then, Byakuya, who is usually so composed, might be at a loss initially. Ichigo, on the other hand, would probably be more straightforward about dealing with it.
In fanfiction, the relationship between Ichigo and Fem Byakuya can be really interesting. It often explores new dynamics that are different from the original story. Writers might play with their personalities and how they interact in various situations, like during battles or in more personal, emotional moments.
One possible plot could be that rukia and byakuya accidentally end up taking care of a baby. They initially struggle as they are not used to this situation. Byakuya with his strict nature tries to impose order while rukia is more lenient. As they care for the baby together, they start to understand each other on a deeper level and their relationship grows stronger.
There is a good chance that such fanfiction exists. Given the popularity of the Bleach series, fans love to delve into different character interactions. Byakuya and Ichigo have their own unique personalities and storylines, which makes for an interesting premise for fanfiction writers to create stories about Byakuya having feelings for Ichigo.