In this fanfiction, Gaara's possessiveness could be demonstrated in different ways. Firstly, he might be possessive in terms of her time. He wants to spend as much time as possible with her. Secondly, he could be possessive about her emotions. He doesn't want her to be too friendly with other guys as he fears she might develop feelings for them. Also, he may be possessive about her safety, always being on guard and ready to fight off any threats to her.
One reason could be that he has deep feelings for her. He might not be used to having such strong emotions for someone and this possessiveness is his way of showing how much he cares.
Their relationship can also be portrayed as a gradually evolving bond. Gaara starts off with a sense of possessiveness that is more about his own insecurities. As the story progresses, Naruto helps Gaara work through those insecurities, and the possessiveness transforms into a more healthy and mutual bond of friendship and loyalty. This is often shown through various adventures and challenges they face together in the fanfiction.
Naruto might be initially confused. He is used to being friendly with everyone, and this sudden possessiveness from Fem Gaara could catch him off - guard. So he may just try to talk to her to understand why she is acting this way.
One popular fanfiction could be 'Gaara's Obsession'. In this fic, Gaara's possessiveness over Naruto is shown through his actions to protect Naruto at all costs. It's full of emotional moments and action scenes.
In fanfiction, Gaara could be possessive of Sakura due to their different upbringings. Gaara was alone and isolated for a long time, while Sakura grew up in a more normal ninja community. His possessiveness could stem from his envy of her normalcy and his desire to keep that 'light' in his life.
One great possessive Gaara x Naruto fanfiction is 'The Desert's Claim'. It beautifully portrays Gaara's possessive nature towards Naruto. In this fic, Gaara is constantly protective of Naruto, which adds an interesting dynamic to their relationship. Another is 'Gaara's Treasured Naruto'. It shows how Gaara's feelings for Naruto grow into a deep, possessive love. He becomes territorial when others get too close to Naruto.
One possible reason could be a deep emotional bond. Maybe Gaara has seen Naruto's unique strength and kindness, which makes her feel a strong connection. It could also be due to a sense of protection. Naruto might have been in situations where he was vulnerable, and Gaara's possessiveness is her way of ensuring his safety.
The theme of jealousy often appears. Gaara may become jealous if he sees Sakura interacting with other male characters, especially those who are also powerful or have a history with her. This jealousy can manifest in different ways, from silent brooding to more aggressive displays of his possessive nature.
In many fanfictions, it often starts with Gaara noticing Naruto's unique qualities. Maybe Naruto's determination or his ability to see the good in Gaara. As Gaara gets closer to Naruto, his protective instincts kick in. He starts to feel possessive when he sees others trying to harm or be too friendly with Naruto. For example, in 'The Bond of Two Souls', Gaara first saves Naruto from a dangerous enemy. This event makes him realize how much he cares about Naruto and that's when the possessiveness begins to grow.