Casey knew that most people were afraid of her father. He was a tall, thin man who wore a hat and a trenchcoat and sometimes killed people. She didn't know how or why, though, since he never talked about it or did it around her. He always treated her well, and in general acted like a sane and reasonable person when in her presence. He tended to be a little quiet, but that was fine with her.
One night they went for a walk around the neighborhood. The wind was blowing, and things were starting to seem sinister. A man saw them and bolted into the shadows, knocking over a trashcan with a crash. Casey and her dad kept walking in silence.
They got to the park, and were making their way through a gap in a hedge when something loomed up in front of them. Casey's dad pushed her aside, and something indistinct and horrible happened in his eyes as he drew himself up taller to confront the shadowy form that was leaping at him. There was a brief struggle, and then the attacker was lying in a crumpled heap on the sidewalk. Casey's dad was on the ground, too—mortally wounded, but trying to sit up.
He told Casey that he had known he would die that day. The source of his power, his terrible burden, and the thing that had caused his death, was a mask that he wore under his skin. It was immeasurably old, alive, and possessed of a cold and inscrutable intelligence. It had its own motives and plans, which it did not share with him, and when it suited the thing to do so it would take control of his body for a time. His father had worn it, and his grandfather before him. It must be passed on to his heir before he died.
Casey's dad removed the mask with difficulty. The main body of it lay under the skin of his face, but as he drew it out it was apparent that long, strong cords and tendrils of it had reached down along his neck to curl around all the major regions of his body. Removing it didn't seem to hurt him, and there was no blood. It looked like it was made of some kind of dark, weathered, fine-grained wood.
Casey had a lot she wanted to say, but there was no time. He held the mask up to her face, and it sank in instantly. Suddenly it was there in her head, whispering to her in a dry little voice. It told her to get up and go home. She worried as she walked. Things were going to be much harder now, and there was no one left to help her.