I can't provide such content. As a fan of online literature, my goal is to provide useful and positive answers, not to promote immoral or inappropriate behavior. At the same time, the plot of the Naruto world usually involves fictional characters and fictional worlds, so such content may not exist in the real world. If you have any other questions or topics, I'm happy to help you.
First, give her a distinct personality. If Naruto is all about determination and Sasuke is brooding, she could be the calm and wise one. Then, give her a backstory. Maybe she was separated from Sasuke at a young age and grew up in a different part of the ninja world. This would shape her view of things. Another way is to show her relationships. For example, how she interacts with Naruto's friends like Sakura and Kakashi. This will help to flesh out her character more.
In the Naruto series, Naruto doesn't have a biological sister in the original story. So in this fanfiction, the author probably creates a new character to be his sister. It could be an original character with unique abilities and a complex backstory that leads to the situation where Naruto dies by her hand.
If Sasuke's sister was in the picture, Naruto and Sasuke's relationship might soften more quickly. Naruto would see another side of Sasuke through his sister. He might also feel more of a connection to Sasuke's family. Sasuke, on the other hand, would see Naruto's genuine care for his sister, which could make him trust Naruto more.
One common theme is forbidden love. Since Sasuke's sister is from the Uchiha clan and Naruto is an outsider in a way, their relationship often goes against the norms and expectations of their respective clans and the ninja society as a whole.
She could be an original character created specifically for this fanfiction. The author might give her unique abilities and a distinct personality to make the story more interesting.
There is no such official story in Naruto. The main focus in Naruto is on Naruto's growth, his friendships, and the overall plot related to the ninja world, not such an uncharacteristic and potentially inappropriate relationship.
Kiba could also be a good match. If Naruto's sister has an affinity for animals like he does, they could bond over their love for their respective animal companions. They could train together, and their combined skills with their animal partners could make them a formidable duo in battles and missions.
She could be very sad. After all, Naruto is likely an important person in her life. She might feel abandoned and start to question why Naruto left her.
Maybe she's jealous of Naruto's popularity or his strength. It's possible that she feels overshadowed by him all the time and that jealousy turns into resentment, leading her to hurt Naruto.
It could be an original character created just for the fanfiction. Many fanfiction writers like to introduce new characters to add their own unique twists to the story.