In "Half-Life," what incident early in the story demonstrates how much time David has begun losing to his drug use?

Frick tells two brief stories: one about shooting at white kids out on the ice, and another about losing most of the vision in his right eye when having a rock fight for fun with other Native kids. David is very nearly wounded in an eye during the stick fight with Tyson and JP, and later, he and Tyson throw rocks at white men outside the bar. He and Frick both engage in a fruitless "war" against the white "enemy," but their physical wounds come from mock battles with other Natives.