A possible plot is in a group of friends who are trying to build a treehouse. The little sister takes control. She first makes a proper plan on paper, measures the materials needed accurately. Then she guides her friends in building it step by step. She ensures safety during the construction process and makes decisions on design changes as they go along. In the end, they have a wonderful treehouse.
The plot could be that in a family business, the little sister, seeing the business in trouble, takes control. She might come up with new marketing ideas, like using social media in a different way to attract more customers. For example, she could start a viral campaign that features the family's products in an interesting and unique way.
In a school project group, there was a little sister, Emma. The group was in chaos as the deadline for the project was approaching. Emma decided to take control. She made a schedule for everyone, assigned tasks according to each person's strength. For example, she knew one boy was good at drawing so she made him in charge of the illustrations. She herself took on the task of gathering research materials and writing the introduction. Under her leadership, the group not only completed the project on time but also got an excellent grade.
It could be a story about a son who becomes overly dominant in family decision - making. Maybe he starts taking charge of family finances previously managed by mom, or he dictates the daily activities of his sisters without respecting their own wishes.
One possible theme could be power and its abuse. If someone is controlling a little sister's mind, it shows an imbalance of power. Another theme might be the struggle for freedom, as the little sister would likely be fighting against the mind control to regain her autonomy. And also, the theme of family and protection, because the situation would call into question how family members should act to safeguard the little sister from such a horrible situation.
It could also be a supernatural entity. For example, an evil spirit or a demon that has latched onto the little sister and is slowly taking over her mind. In some stories, these types of antagonists are used to add an element of horror and the unknown to the plot.
Maybe the sexy little sister is an artist. She creates beautiful paintings that are full of life and passion. One day, a famous art collector comes to town and stumbles upon her work in a small gallery. He is so impressed by her talent and the way she expresses herself through her art that he decides to sponsor her to have her own solo exhibition in a major city, which launches her art career.
A sweet little sister could start a small garden in her backyard. She plants different kinds of flowers and vegetables. As she takes care of the garden, she discovers that there are some little bugs that are also living there. Instead of getting rid of them, she learns about how they are important for the ecosystem of the garden. She then shares her knowledge about the garden and the bugs with her friends and neighbors, spreading her love for nature.
As I have no knowledge of 'little sister a novel', it's impossible for me to describe its plot. You might consider reaching out to book clubs or groups dedicated to reading and discussing novels. They may have members who are familiar with this book and can share insights about its plot.
Maybe it could be about a little sister who accidentally shrinks due to a magical spell. Then she has to face all kinds of challenges in a world that has suddenly become huge for her, like trying to get back to her normal size while avoiding being stepped on by the family cat.
Perhaps in a shrinking little sister story, there's some sort of scientific experiment gone wrong in the house. The little sister is caught in the blast and shrinks. She has to communicate with her family in creative ways since they can't immediately see her. She might use her wits to get their attention, like making tiny fires to create smoke signals. In the end, her older brother, who is a science whiz, figures out how to reverse the process.
One plot could be centered around a family secret. The big sister discovers that she is part of a long line of women who can grow to a giant size. She has to keep it a secret from everyone, including the little sister. However, one day the little sister accidentally finds out. At first, she is scared, but the big sister explains everything. Together, they use the big sister's ability to help their community, like saving it from a flood by building huge dams in her giant form.