She could be a half - blood like Harry. Maybe her mother was a muggle - born witch and her father was a pure - blood wizard. This mixed heritage could give her a unique perspective on the wizarding world's issues regarding blood purity.
Maybe an original character could be created. This sister could be a powerful and wise ninja who has been traveling the world. She comes back to the village just in time to take Naruto under her wing. She could have a special kekkei genkai that she helps Naruto understand and perhaps develop in himself.
One appropriate story could be about how the wife's older sister helps the couple during their wedding preparations. She might use her experience to offer advice on choosing the right venue, the best flowers, and how to deal with family politics during the big day.
I recommend 'One Child, Three Treasures, State Preceptor's Father Don't Think of Running Away' to you. The plot of this novel is similar to what you described. The novel told the story of two sisters. The elder sister was a cruel and money-loving person, while the younger sister was a muddle-headed person. In the end, the younger sister married the older sister's boss, and the older sister had no choice but to marry a silly boy. I hope you like this fairy's recommendation. Muah ~😗
One popular sakura older sister fanfiction might be the one where she goes on a magical adventure to save her family. It's full of exciting plot twists and great character development.
Some Naruto older sister fanfiction focuses on the relationship between Naruto and his sister in the context of the overall Naruto universe story arcs. Maybe she has connections to other important clans or characters. Her presence could potentially change the course of events, like how Naruto interacts with Sasuke or how he approaches his goal of becoming Hokage.
One story could be that the older sister always defends the younger kid at school when bullies try to pick on him. For example, she might stand up to the mean kids and tell them off, making the younger one feel safe and protected.
One challenge could be getting the older sibling to listen. Since they are older, they might not want to follow the little sister's instructions easily.
In some family - centered stories, the little sister is really into girly things like tea parties. She convinces her older brother to participate. She makes him wear a crown and a cape, and they have a 'royal' tea party. Through this, the brother is feminized as he takes part in an activity that is often seen as more suitable for girls. He might even start to enjoy it and become more open to 'feminine' activities in general.
A big challenge can be the difference in interests. The older boy may like more complex and mature things while the little sister might prefer childish games. This can lead to boredom or frustration on the part of the older boy. Also, if there are any safety issues, like if the older boy wants to go out alone or do something risky, the little sister has to be really firm and responsible which can be difficult given the age difference.