Billy Preston

… poison ivy from urinating in the bushes and everyone finding out (hey, scratch-ass, your bum itch?); Billy Preston putting peanut butter in her hair that time she fell asleep in study hall; the pinches, the legs outstretched in school aisles to trip her up, the books knocked from her desk, the obscene postcard tucked into her purse; …

Schoolmate tormented Carrie while she slept in study hall; school context establishes fictional student, not presumed musician.