There is such a person, he is not your parent, but he has the habit of disciplining and restraining you; he is not your friend, but he has the obligation to listen and comfort you; he is not your lover, but he has the responsibility to lend you a shoulder to rely on. Maybe one day, parents will grow old, friends will leave, and lovers will break up. And he will be with you all the way - from the first half of your life to the second half of your life. We call this kind of people - siblings.