The rock wall

A wall of artificial stones gave Rock a scenic option for his descent from school to his apartment. Most of the other university students who lived in the complex used it, though there was a less strenuous route along a sidewalk that went around the wall.

Rock had begun to descend it from school one day when he noticed a blonde-headed man climbing toward him. The man, dressed in dark clothing, scowled. His hands were tucked into the pockets of his black pea coat, and he stared at Rock as they approached each other. Rock was immediately wary. Whereas the wall offered relatively safe lanes, it was steep, with single switch-back trails that would make it easy for anyone to dislodge anyone else. He knew it would offer this man a simple opportunity to push him to serious injury and perhaps death if their paths crossed. He decided to turn back to walk around on the sidewalk.
He kept the man in sight, though, and watched him begin to pick up rocks the size of baseballs and throw them at other students near the top of the wall.