My younger sister was very shy and not strong physically so used to depend on me in all social situations and, generally, to be her protector.
Come teenage years, she lost her shyness and began to run her own life on her own lines and there were some almighty spats as she threw off my tendency to run her life for her, but it didn't last long. As with Auntieflo we stood together through thick and thin
I cannot remember either of us ever playing unkind tricks on each other or anyone else. I have never liked practical joking. I have always considered it a form of bullying as the 'joke' depends on the humiliation of another individual and I would never do that to anyone, least of all my sister.