A long time ago I worked as a volunteer at a hospital. There was a little girl, who suffered from a serious disease. The only chance for her recovery was a blood transfusion from her five-year-old brother, since he had experienced the same disease and had miraculously recovered. Thus he had the needed antibodies to struggle with this illness.
So the doctor told about the situation to the boy and asked him, if he is willing to give his blood to his sister. He hesitated only for a moment, then the little boy took a deep breath and said “Yes, I will do this, if it will save her life”.
During the transmission his sister was lying in bed next to him. The boy looked at her and smiled, but gradually his face became pale and his smile faded. He asked the doctor with a trembling voice: “Will I start to die right now?”
The little boy thought that he would have to give all his blood to save the life of his beloved sister.