One plot twist could be that Inuyasha tries to win Kagome back at the last minute. He realizes he truly loves her when he sees her about to marry Koga. This would create a lot of drama and tension between the three characters.
A really interesting plot twist could be that Kagome actually comes from a long line of powerful miko (priestesses) who have a prophecy that they cannot marry a youkai (demon). When she and Koga are about to get married, she starts having strange visions and powers emerging that make her question whether she should go through with the marriage.
A plot twist could be that Inuyasha is forced to choose between Kagome and saving his friends. Some dark force could put his friends in danger and the only way to save them is to break off his marriage to Kagome. This would create a huge conflict for him as he loves Kagome but also values his friends deeply. Also, Kagome might come from a future where she is suddenly called back and has to find a way to either stay in the past with Inuyasha or go back to her own time, leaving him behind.
The plot could twist when they find out that Kagome's pregnancy is progressing at an abnormally fast rate. This could be due to her connection to the feudal era and the different time - related magic there. It might also be that the baby has some special powers that are causing this rapid development. Additionally, there could be a plot twist where Koga's pack has different reactions to the pregnancy. Some might see it as a sign of weakness, while others see it as a new beginning for the pack.
One common plot twist could be that Koga actually kidnapped Kagome to protect her from a greater threat. Maybe there's a powerful demon that's after Kagome, and Koga, despite his rough ways, believes he can keep her safe. Another twist might be that Kagome discovers she has some hidden power while in Koga's captivity that helps her either escape or gain an understanding of the demon world in a new way.
Well, the plot might involve Kagome's family from the modern world coming to the feudal era for the wedding. Her mother could be a bit worried at first about Kagome getting married in such a different world, but then she sees how much Inuyasha loves her daughter. The story could show how Inuyasha tries his best to make Kagome happy during the wedding planning. He might go on a dangerous quest to find a rare flower that Kagome wants for her bouquet. And then, on the wedding day, they exchange vows in front of all their friends and family, promising to be together forever, and it's a really emotional and joyous occasion.
One possible plot twist could be that while drunk, Kagome accidentally reveals her true feelings for a certain character she has been hiding them from. For example, if she has a secret crush on Inuyasha, in her drunken state, she might blurt out something like 'I've always loved you' which could create a whole new dynamic in their relationship.
Perhaps in the fanfiction, Koga kidnaps Kagome believing she has some special power that can help his wolf demon tribe. He might think that she can heal the sick among them or bring good fortune to their land. However, Kagome doesn't actually have this power, and she has to convince Koga to let her go while also trying not to anger him too much. As she's held captive, she might learn more about the wolf demons and their way of life, which could be an interesting aspect of the story.
One possible plot twist could be that Sakura discovers Kakashi has a secret past she never knew about. Maybe he was involved in some kind of dangerous mission long ago that has consequences in the present. This could put a strain on their relationship as she tries to come to terms with this new information.
One possible plot twist could be that just before the wedding, Ayame discovers a long - lost relative who has some dark secrets about Kouga's family. This relative tries to stop the wedding by revealing these secrets to Ayame. Another could be that on the wedding day, an old enemy of Kouga shows up and challenges him to a fight, putting the wedding on hold. Or perhaps there is a misunderstanding where Ayame thinks Kouga has betrayed her trust in some way, like he made a deal with an enemy for the sake of the tribe but didn't tell her.
Maybe Hikari suddenly gets an amazing job opportunity in a far - off place. This would force them to decide between following Hikari's career dreams and staying in their current comfortable life. It could lead to some really emotional and tense moments in the fanfiction.
One possible plot twist could be a long - lost relative showing up at the wedding and revealing a family secret that threatens to stop the marriage. For example, if there's a feud in the family that was hidden from Heiji and Kazuha.