Karina put down her backpack and dug inside the front pocket for Prem’s small Swiss Army knife. She turned it over in her hand, noting its smooth, unscratched surface. She pulled out the large blade and pressed it gently into her finger pad. Then in a single, swift motion, she drew back her arm and flung the knife into the broken cavern.
An impulsive move that I thought "you will regret having done that later!" It makes sense, though. On the one hand, it was a symbol of her brother yet having it in her possession, she created physical wounds to dull the emotional wounds that she continue to break open each time she thought of him.
