Death's Reading Room
Existing on an unknown plane of existence, this room, which the new incarnation of Death, Billie, refers to as her reading room, houses a near-infinite library of notebooks, each of which lays out in detail a possible death for every being on the planet. Deaths are selected through the choices a person makes in life.
When Billie needs to have a private conversation with Dean about his recent visit to an alternate universe, she shows Dean his notebooks and lists off a few of the possible deaths he may end up having, telling him he may have a heart attack or be burned alive by a red-haired witch or simply be stabbed by a ghoul in a graveyard. She tells him that any of these could be the way he dies but Dean's current suicide is not listed and she sends him back.