One possible plot twist could be that their love is forbidden due to the long - standing feud between their families or clans. Maybe they have to keep their relationship a secret at first. Another twist could be that there's a third character who tries to come between them out of jealousy or a sense of duty to keep them apart.
Well, perhaps in the fanfiction, they discover that their love is somehow tied to a greater prophecy or magical event. They might be the key to bringing peace between their two groups. And then there could be a plot twist where they have to sacrifice their love for the greater good, but in the end, find a way to be together without causing harm.
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 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.
Maybe Harley Quinn's love for Batman causes her to turn against the Joker completely. This would be a huge shift as she has been so closely associated with the Joker for a long time. Her newfound love could lead her to try and reform herself to be worthy of Batman's love, and in the process, she might become an unexpected ally for Batman in his fight against Gotham's villains.
Well, in Bella and Jacob wedding fanfiction, a plot twist might be that Jacob has a vision during the ceremony that shows a future filled with danger for Bella if they get married. Or perhaps Bella's long - lost relative arrives and reveals some shocking information about her heritage that could change the whole dynamic of the wedding. It could also be that the werewolf pack has some internal conflict right before the wedding that threatens to derail the event.
It challenges the original storyline mainly by going against the expected relationships. In the original, their relationship was more of a rivalry. So, having them fall in love completely changes the dynamic. It also challenges the way the characters were initially portrayed in terms of their sexual orientations and their loyalty to their own groups.
One interesting plot twist could be that Bella realizes she doesn't want either of them and decides to go off on her own journey of self - discovery. This would completely change the dynamic of the love triangle.
Well, a plot twist might be that there is a secret alliance among some of the newborns and Jacob's pack. Some of the newborns could be there not to fight against Jacob and Bella but to actually help them. This could be because they are rebelling against the vampire who created them for some unknown reason. And it would completely change the course of the battle.
Another plot twist could be that Molly has her own secrets. Maybe she has a past or a connection that Sherlock is unaware of, and when it's revealed, it either threatens their relationship or actually deepens their bond as they work through the issues together.
Maybe a plot twist is that Jacob has a long - lost relative who shows up just before the wedding. This relative has different ideas about Jacob's future and doesn't approve of his marriage to Renesmee. He tries to persuade Jacob to break off the engagement, which causes a rift between Jacob and Renesmee as they deal with this unexpected interference.
Well, it could be that the pregnancy was part of a prophecy. Jacob and Rosalie initially didn't know about it, but as the pregnancy progresses, they start to learn more about this ancient prophecy. This could lead them on a journey to protect the baby from those who would use it for their own gain. It also might bring some long - lost relatives or allies into their lives to help them through this strange situation.