In the fanfiction, perhaps there's an alternate universe where Ichigo and Rukia are not bound by the usual rules of their world. They meet in a more normal setting, like a high school in the human world. They fall in love like any normal couple. Rukia has to hide her true identity at first, but as their relationship deepens, she reveals all. They decide to get married, and Ichigo has to learn all about the Soul Society traditions for the wedding. It's a story full of humor as Ichigo tries to fit into Rukia's world and they build a future together.
One possible plot could be a post - battle scenario. After all the chaos and fighting they've been through, Ichigo realizes his true feelings for Rukia. They start to secretly date while trying to maintain their duties as Soul Reapers and protectors of the living world. Eventually, their friends find out and support them wholeheartedly. They plan a simple yet beautiful wedding in the Soul Society, with all their friends and comrades in attendance, and they live happily ever after, constantly going between the Soul Society and the living world to visit their loved ones.
The plot could revolve around a prophecy. There is an ancient prophecy in the Soul Society that foretells of a union between a powerful Soul Reaper and a human with special abilities, which of course is Ichigo. Rukia is initially skeptical but as they go on adventures together to save both worlds, their bond grows stronger. They gradually realize that they are the ones in the prophecy. Their marriage then becomes a symbol of hope and unity between the two worlds, and they have to face many challenges from those who oppose the union but in the end, they are victorious and get married.
Well, a plot twist could be that one of them loses their powers right before the marriage. For example, if Ichigo loses his Soul Reaper powers, he might start to doubt if he can protect Rukia and their future together. Or perhaps Rukia is suddenly called back to Soul Society for an important mission that she can't refuse, and it's a mission that might keep her there for a very long time, putting their relationship to a hard test. Also, there could be a new character introduced who has a mysterious connection to either Ichigo or Rukia and tries to disrupt the wedding.
One emotional moment could be when Ichigo first proposes to Rukia. He might be a bit clumsy with his words, but the sincerity in his eyes would be clear. Rukia's shocked and then tearful acceptance would be very moving. Another moment could be when they exchange their vows. They would pour out their feelings for each other, talking about how they've saved each other's lives in more ways than one and how they can't imagine a future without the other. It would be a deeply emotional scene.
One possible plot twist could be that an ancient curse is revealed just before the wedding. This curse might be related to their different spiritual powers and threatens to tear them apart. For example, it could cause Toshiro to lose his ice powers, which are an essential part of his identity, and he might feel unworthy of Rukia. Another plot twist could be the interference of a powerful enemy. Maybe a rogue Soul Reaper who has a vendetta against Toshiro's division decides to use the wedding as an opportunity to strike. They could try to kidnap Rukia to lure Toshiro into a trap. Or perhaps a discovery that their marriage has been pre - ordained by some higher spiritual force for a greater purpose, like saving the Soul Society from an impending doom, and they have to quickly come to terms with this new - found responsibility.
Well, the plot might involve some kind of prophecy or destiny that links Ichigo and Kukaku together. Maybe there's a mysterious force in the Soul Society that decrees they should be together. Their relationship could start with a shared adventure, like they have to team up to fight a powerful enemy. During this time, they start to understand each other on a deeper level. For the wedding, it could be a grand affair with all of Ichigo's friends from Karakura Town and Kukaku's allies in the Soul Society coming together. There could be some comical moments too, like Ichigo trying to understand the complex wedding traditions of the Soul Society.
The plot could involve Nemu saving Ichigo's life during a fierce battle. This act makes Ichigo see Nemu in a new light. They begin to spend more time together, sharing their past traumas and dreams. As they fall deeper in love, they decide to get married. However, they have to keep it a secret at first due to the political situation between Hueco Mundo and Soul Society. Eventually, their love story becomes an inspiration for others in both worlds.
In some fanfictions, it might be because of jealousy. For example, if Rukia spends a lot of time with another character, Ichigo could get pissed. He might have feelings for her that he hasn't fully realized or admitted, and seeing her with someone else stirs up his anger.
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 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.
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.
A plot twist might be that Rangiku discovers a long - lost family secret just before the wedding. For example, she could find out that she has a connection to a powerful and mysterious clan that has some sort of vendetta against Ichigo's family. This would put a strain on their relationship as they try to figure out how to deal with this new information.