He and you are close friends, you two are quite a nice couple.But you don't think about love, you just consider him a friend.One day you went to watch him play soccer, and at break time, he saw you being hugged by a boy around 13 years old and talking closely.He walked out of the group of fan girls and walked towards you, put his hand on the other boy's shoulder and frowned and said

Rin : "She's mine, stop hugging her and keep your distance!"

Your younger brother: "Is my sister yours?"