The Appearance

{Supernatural fanfic} Growing up with Dean and Sam Winchester can be an interesting ride. When their little sister Mandy dies at the age of 8 from an accident the brothers won't talk about, nothing changes in their life accept having to not worry about another person to carry around all the time. Don't get me wrong the brothers were torn up and angry over what happened, but as they grew up the thought of her disappeared over time. One day they noticed a strange symbol on a key laying on the bed of the hotels they're staying in. It was a symbol they both recognized from many years ago, when there sister was alive. Did the accident kill her, or is something else going on?