My mother died of cystic fibrosis before I knew her. I was...

My mother died of cystic fibrosis before I knew her. I was two years old, and I don't remember her. I do remember, though, when it was just my father and me, before he met the woman who would become the mother who raised me, before my younger sister, Gillian. It was just the two of us, and he was my whole world.