Write a story that seems normal on first sight , except for one small detail that makes it extremely creepy on a more careful reading [ WP ]

It was a fine June morning, warm with a slight breeze that played through my hair. I swung gently on the swing that hung from an oak tree in my grandma's backyard. Darcey sat on my lap, and I caressed her softly. She seemed to enjoy the weather just as much as me, gleaming in the sun. What a cute little pet. 
 
 After about half an hour of enjoying the swing, Amy came into the yard. Her face was as bratty and ever. `` What do you want?'' I asked, glaring. A smirk formed upon her face, filling me with heat. `` Grandma wants you to come help her wash the dishes,'' she stated, and then a bit more quiet, `` maybe it'll help clean you up a bit too.'' 
 
 Amy's insults were stupid and did n't make sense most of the time, but they angered me all the same. I'd had enough. I threw Darcey at her, and she attacked. I'd always admired the way she fought, quietly and swiftly, taking down her opponents in one plunge. 
 
 Darcey was n't like other pets. She was loyal like a dog, but did n't wag like one. She was stealthy like a cat, but had no feet to land on. She traveled fast like a fish, but had no fins. She was a knife, my cute little pet.
