She walks briskly down the city sidewalk, her blond hair bouncing against her shoulders, her cheeks flushed, a gym bag looped over her forearm. When she reaches her apartment building, her hand dips into her purse and pulls out her keys. The street is loud and busy, with yellow cabs racing by, commuters returning from work, and shoppers entering the deli on the corner. But my eyes never stray from her.

She pauses in her entryway and briefly glances back over her shoulder. An electrical charge seems to pulse through me. I wonder if she feels my stare. Gaze detection, it's called—our ability to sense when someone is observing us. An entire system of the human brain is devoted to this genetic inheritance from our ancestors, who relied on the trait to avoid becoming an animal's prey. I've cultivated this defense in myself, the sensation of static rising over my skin as my head instinctively lifts to search out a pair of eyes. I've learned the danger of dismissing that warning.

But she simply turns in the opposite direction, then opens her door and disappears inside, never looking my way.

She is oblivious to what I have done to her.

She is unaware of the damage I have wrought; the ruin I have set in motion.