Another plot twist might be that Ichigo is initially oblivious to Yoruichi's feelings. He could be so focused on protecting his friends and fighting Hollows that he doesn't notice the subtle signs of her love. Yoruichi then has to find a way to make him aware without being too forward, which could create some really interesting and comical situations.
One possible plot twist could be that Yoruichi's love for Ichigo is forbidden in the Soul Society. Maybe there are rules against such relationships between different 'classes' or species. For example, Yoruichi being an ex - captain and Ichigo being a human - turned - Soul Reaper - substitute. This could lead to a lot of drama as they try to hide their feelings from others.
One plot twist could be that they face opposition from the Soul Society. Since Ichigo is a substitute Soul Reaper and Yoruichi has a complex history there, the elders might try to stop the marriage for political or traditional reasons.
A plot twist could be that an old enemy of Yoruichi resurfaces, seeing their marriage as an opportunity to get revenge. This enemy could be someone from her past in the cat clan or a Shinigami she had crossed paths with before. Now, Yoruichi and Ichigo not only have to plan their wedding but also defend themselves and their loved ones from this new threat.
Well, a really interesting plot twist could be that Yoruichi is actually a reincarnation of an ancient soul that was once bound to Ichigo's family in a very different way. And their marriage is a way to restore some sort of balance in the world of Bleach. Also, what if Ichigo suddenly starts to lose his powers during the wedding preparations? It could be due to some sort of curse or a side - effect of their impending union. Then they have to figure out how to get his powers back without cancelling the wedding.
The fanfiction could start with Hollow Ichigo being on a rampage. Yoruichi decides to step in to stop him. But instead of a fight, they find themselves in a situation where they are forced to cooperate. As they interact more, a strange bond forms between them. Hollow Ichigo starts to develop a sense of respect for Yoruichi's strength and intelligence, and Yoruichi begins to understand the pain and chaos that exists within Hollow Ichigo.
One possible plot could be them adjusting to married life while still dealing with the spiritual world threats. Maybe Ichigo is trying to balance his duties as a protector and a husband, and Yoruichi is using her experience to guide him in both aspects.
One possible plot could be that Ichigo and Yoruichi are thrown into an alternate dimension where they have to team up to find a way back home. Along the way, they discover new powers within each other and face powerful enemies together.
Perhaps Naruto's relationship with the other ninja in Konoha is affected. Since Yoruichi has a different set of values and skills compared to the traditional Konoha ninja, Naruto could be seen as an outlier. This could lead to some initial misunderstandings and later, a new form of respect from his peers as they see the effectiveness of his unique upbringing.
One possible plot could be that they discover the pregnancy unexpectedly. Maybe they were in the middle of some big battles or adventures, and then they have to suddenly deal with this new situation. Yoruichi, with her experience, might start preparing for the arrival while Ichigo is still in shock but slowly comes to terms with it and becomes very protective.
Rukia might be initially shocked. Since she has a strong bond with Ichigo and also respects Yoruichi, she would have to adjust to this new relationship dynamic. She could be a bit hesitant at first, but eventually come to accept it.
One possible plot twist could be that Aphrodite's love for Hephaestus is a ruse created by another god to cause chaos. Maybe Ares, jealous of Hephaestus, convinces Aphrodite to pretend to love him. This would lead to a series of events where Hephaestus starts to believe in the love, only to find out it was false later, causing great heartbreak for him.