One interesting sister and big brother story could be when the big brother taught his sister how to ride a bike. He patiently ran beside her, holding the seat, until she got the hang of it.
One 'big brother big sister story' could be about a big brother teaching his little sister how to ride a bike. He patiently held the bike while she pedaled, and when she finally rode on her own, it was a really heartwarming moment.
One 'brother big sister story' could be about how the big sister always protects her younger brother from bullies at school. She stands up for him and teaches him how to be brave.
One 'little brother big sister story' could be about how the big sister always protects her little brother from bullies at school. She stands up to the mean kids and makes sure her brother feels safe.
There might be a story where the big sister stands up for her little brother at school. When some kids are picking on him, she uses her wits and courage to make them stop, showing her protective side.
One sister brother story could be about how they teamed up to save a stray cat. The sister noticed the cat first, and then she told her brother. They worked together to find a box, some food, and then took the cat to the vet. Another story might be that they both entered a school talent show and did a magic act together, with the sister as the assistant and the brother as the magician.
One inspiring story could be about a big sister who helped her little sister in the program improve her reading skills. She spent hours every week reading with her, and eventually the little sister went from being a struggling reader to an avid one.
One 'big brother story' could be about a big brother protecting his younger sibling from bullies at school. He stands up for the little one and scares the bullies away.
One 'big brother big sister horror story' could be about a big sister who always seemed nice but at night she would turn into a menacing figure. She would stand over her little brother's bed with a blank stare and cold hands, as if she was possessed. It was so terrifying that the little brother couldn't sleep at night.
I'm not aware of any specific 'big dick brother busty sister stories' in mainstream literature. Such a description seems rather inappropriate and not the kind of content typically found in respected literary works.
One story could be about a brother and sister who find a lost puppy in the park. They take it home and try to hide it from their parents at first. But eventually, they realize they should tell the truth. Their parents are proud of them for being kind to the puppy and they all keep the puppy together.