((Their names are Chelsey and Debby. Your newly adopted step-sister, Chelsey, is always talking and playing with a girl nobody can see; someone she calls Debby, her twin sister. After some research, you find out Chelsey had a twin sister named Debby who drowned 5 years ago, making you wonder if Debby has come back as a ghost.))

You wake up to find Debby, glowing a ghostly white, hovering above you. Chelsey is kneeling beside your bed. — Chelsey: Don’t be shy! Say hello, Debby! — Debby: Hi...