The signs are quite obvious in some fanfictions. Sasuke will often interfere when Sakura is making plans with others. He'll try to change the plans so that it involves just the two of them. And he has a habit of giving death glares to anyone who he thinks is getting too friendly with Sakura. This shows his strong possessive nature towards her.
In some fanfictions, Sakura's possessiveness shows when she defends the reputation of Team 7. If someone speaks ill of the team, she will be quick to jump to its defense. This is because she feels a strong sense of ownership towards Team 7 and doesn't want it to be slandered or disrespected in any way.
In many fanfictions, Sasuke's possessiveness is tied to his deep emotional connection with Naruto. He might feel that Naruto is the only one who truly understands him. So, when Naruto spends time with others, Sasuke can get jealous or possessive. For instance, there are stories where Sasuke gets moody when Naruto is training with other ninja. He doesn't like sharing Naruto's attention. This shows his possessive side in a more complex emotional way.
In fanfiction, Sakura's possessiveness can be portrayed by her constantly wanting to be around Naruto and Sasuke. She might insert herself into their conversations or activities, not wanting to be left out. It's like she feels that she has a special claim on their time and attention.
It could also be related to Sakura's strength. Sasuke is constantly striving to become stronger. If Sakura somehow shows a weakness or makes a mistake during a fight that he thinks could have been avoided, and it has negative consequences for their situation, he might get angry at her for not being more capable.
Well, Sasuke's cold attitude could be a reason. He is often distant and unresponsive to Sakura's feelings in the original story, and in fanfiction, this can be exaggerated, making Sakura angry. For instance, if he ignores her attempts at conversation or help.
If she starts showing more interest in other types of fanfiction or non - fanfiction works. For example, she might be more into fanfiction about other Naruto characters or completely different stories from other series. This shift in focus indicates her loss of interest in Sasuke fanfiction.
One common sign could be excessive control. For example, if Sasuke in the fanfiction constantly restricts Sakura's actions or who she can interact with. Another sign might be verbal aggression, like Sasuke yelling at Sakura in a demeaning way. Also, if there's a pattern of Sasuke ignoring Sakura's boundaries, such as physically getting too close when she doesn't want to, it can be a sign of an abusive relationship in the fanfiction.
Sasuke's possessiveness can be portrayed realistically through his actions and words. He might not be very vocal about his feelings, but his actions like always staying close to Sakura when Naruto is around or getting irritated when Naruto makes Sakura laugh too much can show his possessive nature. Also, his internal monologues in the fanfiction can give readers an insight into why he feels possessive of both of them.
One sign could be that Kyuubi gets jealous when other characters get too close to Naruto. Maybe it tries to interfere or make its presence known in a way that scares off the other characters. Another sign is that it might be overly protective of Naruto in dangerous situations, more so than just a normal sense of helping. It could also be possessive in the way it shares its power with Naruto, as if it's something only Naruto is entitled to among all the characters in the fanfic.
Well, one possible reason could be that Sasuke's mistake might have put their team in great danger. For example, if his actions led to the enemy getting an upper hand during a battle, endangering not only his life but also those of his comrades like Sakura. Sakura, who values the safety of the team, would then resent Sasuke for his mistake.