In the dawn of Equestria, several ponies were given unique jobs to aid the Princesses in making the world around them run smoothly. Of the offices created, by far the most important was given to a pony by the name of Mortis--the office of death. His job was simple: he was to collect the souls of ponies dead before their time, and send any lingering spirits--in the forms of ghosts--back to eternity.

Centuries marched by, and Mortis grew weary of his job. He appealed to the Princesses, who saw the pain in his inability to live a normal life. Princess Luna gave him a task. She said that if he could give the office to another pony--willingly--he could live his life as a normal pony, and vacate the office of Death.

Thus, the office changed many times over the years. The office brought with it some power, and much responsibility. In time, without fail, whoever held the Death cloak eventually wanted to pass it on, and the rules to do such never changed. Now, the current Death, a pegasus by the name of Dashing Cloud, is ready to move on. An earth pony by the name of Rose Petal is nominated, the only pony alive who could fill the role.

But, as she will quickly find out, Death is not a job for the faint of heart.

(Idea for personified Death "borrowed" from Piers Anthony. All else is my own brain's creation)