Like the rest of his siblings, Destiny is neither a mortal being nor a god, he is the personification of Destiny itself. As the universe came into being, so it would be that it would come to its final destiny, its end. Also Destiny is the only member of the Endless that is not created by Neil Gaiman.
Blind, Destiny appears as a man cloaked and hooded an indeterminate color of brown, grey, and sometimes purple who is chained to a book which contains the story of everyone, of everything. Sometime things appear in his book before they happen, sometimes as they happen. Destiny’s realm is “his Garden”, a hedge maze which can be reached through all mazes. At it’s center is his castle complete with silent “fluttering” attendants. If family meetings are called, Destiny is usually the host.
Destiny was created by Marv Wolfman and Benrie Wrightson first appearing in Weird Mystery Tales #1 in 1972 as the host introducing stories. He also made frequent guest appearances in other characters books and was a long running host in Secrets of Haunted House.
In the 90's writer Neil Gaiman revamped many older DC horror properties including Destiny for his series The Sandman. Destiny was not changed a great deal, but was now revealed to be the part of a family of seven Endless, all personifications of concepts and human experience.
Destiny rarely, if ever, actively involves himself in anything. His duty is merely to read and observe through his book and he carries it out assiduously. But every great once in a while something will make him step beyond the normal bounds of his duty. To his surprise, the Three Fates appeared in his garden, and he called a family meeting for a purpose unknown even to him. At the meeting Desire taunted Dream for condemning a former lover to Hell for thousands of years. Death agreed with Desire and so Dream left to free the woman from imprisonment (leading to Lucifer giving the key of Hell to him). As soon as Dream left, Destiny declared the meeting over.
Delirium has also pointed out that “there are some things that are not in your book.”
Major Story Arcs
Books of Magic
It also seems that if the future Mister E and Timothy Hunter went to, the end of everything, that solely two beings exist, Destiny and his younger sister Death. It seems that at last she has come to take him and at last he can lay down his burden, turn the final page of his book, and close it, something he seems very grateful to her for letting him do. After he closes the book he begins to shimmer and disappear...leaving only Death, E, Tim and Yo-Yo behind, though in the end he was the second last being to exist.