How do Katie and Nancy meet in the story, Crosses?

Katie and Nancy meet in the bathroom at their high school during their 9th-grade year. Nancy is smoking a cigarette, finishing up vodka hidden in a shampoo bottle, and just starting to carve a cross into her own skin with a piece of jagged glass. She is in the process of cutting, when Katie interrupts her and asks her for a cigarette; that is when Nancy notices that Katie has crosses carved into her skin as well.