The Other Side of the Mirror

Why was the mirror showing me a different image? I stepped back a few steps before looking at the full image of myself. My hands were on my hips and my face was pulled into an expression of annoyance. I looked down at my arms and realized that they were down at my sides. I looked back up at the incorrect image and saw the malicious glint in my reflections eyes. She raised an arm and waved at me, her fingers darting back and forth. I knew for a fact now that my face had a horrified expression. Before I knew it, she stuck her arm out in front of her, grabbed the collar of my jacket, and pulled me back into where she was standing. The mirror rippled from the sudden movement as she jumped into the space I was standing in before and brought her left hand back and forth from the top of the mirror to the bottom. It registered in my head a few moments later that she had switched places with me