Explanation: The song Hey Brother by Avicii is about a man talking not only about his blood (biological) brother, but also about his blood (biological) sister. He says there is "nothing in the world he wouldn't do" for them. He constantly mentions the world ending and says that he would still help out his siblings. The fact that they are related by blood makes their bond unbreakable. He is always willing to help and be there for them no matter the situation.