One story could be that the older brother took the little sister's favorite toy without asking. The little sister got really angry and started hitting him with a small pillow. She chased him around the room until he gave the toy back.
There was a time when the older brother ate all the candies that were supposed to be shared between him and his little sister. The little sister was furious. She first threw her doll at him and then ran towards him and started hitting his back. The older brother realized he was wrong and apologized later.
Jealousy can be a reason. Maybe the older brother gets more attention from parents or grandparents, so the little sister lashes out at him.
There was a time when the little sister knew her older brother was shy. So, during family gatherings, she would tell embarrassing stories about him in front of everyone. She thought it was funny, but it really made the brother uncomfortable. This is a way she bullied him, by intentionally making him feel awkward in social situations.
One possible story could be about a little sister who is very bossy towards her older brother. For example, she might make him do her chores by using her charm and a bit of trickery. She convinces him that it's his role to help her out all the time.
One story could be that the older brother is always late for school. The little sister, who is very punctual, makes a schedule for him and strictly enforces it. Every morning, she wakes him up early and checks if he has completed all his preparations. If he tries to be lazy, she scolds him gently but firmly.
Well, in one story, the little sister was really into dancing but was shy. Her older brother, who was quite popular, encouraged her. He even made a small stage in their backyard for her to practice. And he would be her first audience, giving her confidence to perform in front of others.
Here's a role reversal story. The older brother was going through a tough time after losing his job. Instead of him being the strong one, the little sister took on that role. She found him part - time jobs to apply for, gave him pep talks every day, and even cooked for him. She basically became the one in charge of his well - being, which is quite different from the traditional older - younger sibling dynamic.
This is a rather unusual situation in most cultures. However, in a make - believe or very young children's play scenario, one could imagine a story where a little brother, perhaps in a game of 'pretend family', tries to diaper his older sister's doll as if it were his sister. But in real - life, this goes against typical social norms.
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.
Well, once my little sister got really mad at me because I ate the last piece of her favorite cake. She started hitting me with a pillow. It was more annoying than painful really. I just laughed it off in the end.
One story could be about a family where the older brother is very shy and timid, while the little sister is bold and brave. For example, when facing a bully at school, the older brother is too afraid to stand up for himself, but the little sister steps in fearlessly and scares the bully away.