scars to match the inside

It was sleek, like a fountain pen, with a thin triangular blade at the tip. I picked it up and laid the blade against a doily. The little knots came undone, just like that. I touched the blade to a piece of ribbon draped across the table and pressed, ever so lightly. The ribbon unfurled into two pieces and slipped to the floor without a sound. Then I placed the blade next to the skin on my palm. What happened next was that perfect, straight line of blood bloomed from under the edge of the blade. I watched from above, waiting to see how big it would get before it burst. When it did, I felt awesome. Satisfied, finally. Then exhausted (McCormick).
Most people cringe at the sight of blood and the feeling of a sharp object against their skin, but there are some, just like the girl in the excerpt above from Patricia McCormick’s book ...