In the fanfiction, it could start with Sasuke challenging Gaara to this fight for Sakura. Gaara accepts calmly. At first, Sasuke uses his Sharingan to quickly analyze Gaara's sand techniques and attempts to find a weakness. Gaara, however, has a deep well of chakra and is able to keep up with Sasuke's attacks. As the battle continues, the village elders or other characters might get involved, either trying to stop the fight or influencing the outcome. This could also lead to Sakura having to make a choice between the two, not just based on who wins the fight, but on how they conduct themselves during the battle.
A plot development could be that Gaara and Sasuke start the fight. Sasuke tries to taunt Gaara about his past and how he could never truly understand Sakura like he does. Gaara, in response, shows his determination through his sand attacks. As the fight progresses, Sakura starts to see a side of Gaara she never knew, which makes her question her feelings for Sasuke. Meanwhile, Sasuke becomes more and more frustrated as he realizes he might be losing Sakura's attention, which makes him fight even more recklessly.
For Sakura, she might become more confident in her combat abilities. Working with Gaara, who has such strong and intimidating power, could push her to step up her game. She could also develop more empathy as she gets to know Gaara's troubled past. For Gaara, he could start to open up more to others. Sakura's kindness and determination might make him realize that not everyone is out to harm him.
One possible plot could be a tournament - style setting where Gaara and Sakura are pitted against each other. They fight, and Sakura tries to use her medical knowledge to find a weakness in Gaara's sand defense.
Gaara might start to show more of his soft side. With Sakura by his side, he could become less isolated and more involved in the social aspects of his village. His leadership style could also change, becoming more collaborative. Sakura, she would become more in tune with the desert environment and the needs of the Sand Village. She would probably develop her fighting style to incorporate some of the Sand techniques, which she learns from Gaara. Also, her understanding of love and family would deepen as she builds a life with Gaara.
Perhaps the plot could involve a misunderstanding. Gaara is sent to capture or subdue Sakura because she's suspected of something she didn't do. Sakura, of course, won't go down without a fight. She tries to reason with Gaara at first, but when that fails, she attacks. The fanfic could then explore how they gradually learn the truth during the fight. Gaara might start to respect Sakura's tenacity and Sakura might understand Gaara's loyalty to his village better.
For Gaara, he could start off as a loner in high school, but through his interactions with Sakura, he could become more sociable. He might learn to trust others more and let go of his past traumas. Sakura could develop from being just a girl focused on her studies and friends to someone who is more empathetic towards those with a difficult past like Gaara.
For Sasuke, he might develop more trust in his comrades. In fanfiction, he could start to rely on Tenten's strategic thinking when it comes to weapon - based battles and Sakura's quick medical responses. This would be a big step for Sasuke who has been so used to relying on himself. For Tenten, she could gain more confidence in her abilities as she is often overshadowed by other characters. Working with Sasuke and Sakura, she could shine in battles and her weapon skills could reach new heights. Sakura, on the other hand, could develop a more assertive side. Instead of just being in the background of Sasuke's story, she could take the lead in some situations, especially when it comes to medical emergencies or diplomatic situations within the ninja village.
Well, perhaps in the fanfiction, Sakura is kidnapped by Sasuke because he wants to use her as a bargaining chip against Konoha. Then, the story could involve the other Konoha ninjas coming together to strategize a rescue mission. They might have to deal with Sasuke's new and powerful abilities that he has acquired during his time away. Sakura, while kidnapped, could also try to talk some sense into Sasuke, appealing to their past friendship and her feelings for him.
Another aspect could be that Sakura is initially hesitant to take Sasuke back. She could have doubts about whether he has really changed or if he will just leave her again. So, there could be a lot of emotional turmoil between them as Sasuke tries to convince her.
Sasuke could initially be a vampire who is full of anger and resentment, maybe because of how he was turned. But Sakura's positive attitude and kindness could start to soften him. He might start to open up about his past and his feelings. Sakura could develop from a somewhat naive vampire into a more worldly and wise one. She would learn about the darker side of the vampire world through Sasuke, and this would change her. Maybe she would become more cynical at first, but then find a balance between her old self and the new knowledge she has gained.
For Sakura, she could grow in terms of her leadership skills. If they encounter any difficulties in the forest like being chased by a group of wild animals or getting caught in a dangerous situation, she could step up and lead the way out. Sasuke might then realize that Sakura has the potential to be a great leader. And for Sasuke himself, he could become more open to the idea of a relationship with Sakura. The seclusion of the forest could provide the perfect backdrop for him to explore his feelings for her.