A smile in the reflection

In the morning, I went to the bathroom to take a shower. We'd recently renovated, and the bathroom was brand new: white walls, white tiles, glistening in the light of three 100-watt bulbs. After finishing my shower, I, content with life and whistling cheerfully, went to the kitchen for breakfast. As I passed the mirror in the hallway, I noticed I was smiling broadly. My mood lifted even more.

That evening, before bed, I took another shower and noticed something was wrong with the bulbs; they were glowing very dimly. I went to the kitchen for spare bulbs and replaced one, but it, too, was still fuzzy. I figured it was the wiring and decided to shower in the dim light for now. Standing in the bathtub, I looked at the large mirror opposite. My face in the reflection—it was smiling again! I touched my lips—no, I hadn't meant to smile at all. But the reflection's smile grew wider and wider.

The dim lighting made it hard to make out the details, so I stepped out of the bathroom and walked over to the mirror, though a chill ran down the back of my neck. The smile grew wider and wider, gradually turning into a feral grin. I saw the corners of her mouth slowly creeping toward my ears, and I wondered if I was hallucinating. But what could have caused them? Surely not the lamb cutlets I'd had for dinner. I stepped back from the mirror, took a deep breath to shake off the vision, and for some reason decided to count my teeth in the reflection.

The smile reached my ears, and my chin sank. But I kept counting out of curiosity.

Thirty-six – thirty-seven – thirty-eight…