The plot might develop with the introduction of a third party that either tries to reconcile them or makes the situation worse. If there is a character who is friends with both, they might try to make them see each other's good sides. Or, a villain could use their hatred to his advantage.
Often, it starts with the establishment of their dislike. Then, there could be a series of confrontations. For instance, they might argue or compete in some way, like in a ninja mission where they constantly try to outdo each other.
Often, the plot starts with the sudden or gradual replacement of sakura by karin. This could be due to a spell, a twist of fate, or a decision made by some higher power in the fictional world. Then, karin has to deal with the consequences and expectations that were previously associated with sakura.
It could also be a misunderstanding. Perhaps Karin is misjudged by Sakura in the fanfic. Maybe Karin did something that was misinterpreted as malicious towards Sakura or someone she cares about, leading to the hatred.
One option could be to simply avoid showing Karin any Sakura fanfic. Respect her feelings and keep that type of content away from her.
Often, it starts with Sakura having internal doubts and slowly realizing that things aren't as she hoped in her marriage. For example, she might notice that Sasuke doesn't communicate well with her.
The plot may develop with Naruto finding new interests or friendships that draw his attention away from Sakura. He could become involved in a new mission or training regime that makes him see his relationship with Sakura in a different light. And as he pulls away, Sakura might start to realize she's losing him and try to win him back, but it's too late because Naruto has already made up his mind.
It might develop it through a series of flashbacks. The fanfic could show the events leading up to Sasuke's mistake and Sakura's initial reactions. For example, it could start with a scene where Sakura is shocked by what Sasuke has done, and then through flashbacks, we see the build - up of her feelings.
Well, in Sasuke and Sakura bullying fanfictions, the plot development can be quite interesting. At first, there might be a build - up to the bullying situation. Maybe there are some underlying issues between Sasuke and Sakura and the victim, like jealousy or competition. Once the bullying starts, it can spread like wildfire in their social circle. The reactions of other characters are crucial. Some might side with Sasuke and Sakura, while others will be appalled. As the story moves forward, the bullied character may try to find a way to expose them or get revenge. This could lead to a series of events where Sasuke and Sakura have to face the music, and the fanfiction could end with either their redemption or their downfall, depending on the author's intention.
Often, it starts with small incidents that show Annabeth's dislike. For example, she might give Rachel cold looks or make snide remarks. Then, as the story progresses, the tension builds. Maybe they end up competing in some way, like for a leadership position in a group.
Often, after Sakura makes Naruto cry, Naruto might initially be in a state of shock and sadness. He could then distance himself from Sakura. For example, he might stop going on missions with her or avoid her in the village.
Often, it starts with the incident that causes the concussion. Then it shows how Harry's daily life is disrupted. For example, he may struggle in his classes or have difficulty with his Quidditch training.