What would happen if one of my family members used drugs?

Just for example, if my big brother started using drugs, all of my family members, even I will be worried about my brother's behavior. At first I think my dad and my mom would deny the fact that my brother is on drugs but when they come to realize that it is true they would get really mad. I cannot imagine how mad they are going to be because I don't think they will ever be as mad as this in their entire lives. Maybe I'm going a bit extreme here but I think one of the possibilities is my dad quitting his job and going into the woods to live and disowning my brother. Also if my brother really was on drugs I think he would become a theif since he doesn't have any money because my dad will surely not support my brother with money. I may have gone to far when I said that he would disown my brother. I think he will first get mad then persuade my brother not to take drugs because he is a caring and a loving father. In this scenario I think my role here is to keep my family together. I'm sure things will fall a apart and it is my job to keep them together. If my father wants to disown my brother I should persuade him not to disown him. Then I should persuade my brother not to take drugs.