How can a younger brother take care of his younger sister and send a circle of friends?

A brother's concern for his sister can be sent to a circle of friends. The words "sister, sister for life, sister" are really too heavy.

Sister, originally refers to a woman older than herself with her parents or peers. It also refers to women of the same age who are older than themselves, women who claim to be about the same age, and young women. Later refers to any woman older than herself.

My sister will always be my sister and my brother will always be my brother, just like that family tree. You are a branch, I will do it, and my mother is our root.