Reflection by Will Hunter is a short story, but would probably work better as flash fiction. Sabeth's life follows a self-destructive pattern, so many of the scenes are repetitive and unnecessary. However, the idea that one's reflection could have its own thoughts and feelings, including hatred and rage, is pretty damn scary. While underdeveloped, the psychological aspects of the story give an interesting depth to the frightening problem Sabeth has to face...in the mirror.
Some people are afraid of clowns, ghosts...usually some sort of entity...I've always had a fear of mirrors and glass. I've never had an issue with my own reflection, but the idea that one day my mirror self might move out of sync is terrifying enough to prevent me from staring too long.
When I was in my early 20s, I had a recurring nightmare of little demons (kind of like the ones in The Gate) trying to pull me through a mirror. I became convinced, if they ever succeeded in the nightmare, I would never wake up. I was lucid enough to try and change events, such as offering the demons ice cream (a friend suggested that I try something ridiculous), but they only grew infuriated with my efforts to change the dreamscape.
I never did get rid of them on my own...another dream entity showed up, more frightening than the little demons...he scared them away. That particular entity haunted my dreams and nightmares for YEARS...but it's a story for another time...