Desire

Desire is the third youngest of the Endless and the twin of Despair. The anthropomorphic personification of its name, Desire blends in effortlessly with whatever environment it finds itself in. It lives in the heart of a massive flesh-and-blood statue of itself, known as the Threshold. Desire's sigil is a heart of cut glass.

Appearance
Desire is described as being of medium height, and smelling faintly of summer peaches. It is a strikingly beautiful, androgynous figure of gender-fluidity; it can be male, female, both, or neither as the situation warrants. Desire's smiles are brief and sharp, its skin is "pale as smoke," its hair midnight black, and its eyes are "tawny and sharp as yellow wine." Desire casts two shadows, one black and sharp, the other translucent and wavering.

Personality
Desire is easily the most casually cruel of the Endless. It seems obsessed with interfering with the affairs of its elder siblings and has a particular animosity toward Dream. The motivation behind its attitude is not clear but seems to be simply a vicious variation on childish one-up-manship. Desire may not be entirely aware of the consequences of its actions, but considers any consequences ultimately unimportant, an attitude which angers Morpheus and Death in particular. Desire sometimes acts in concert with Despair and Delirium. Desire is much more distant from Dream, Death, Destiny and Destruction, than Despair or Delirium. A forgiving interpretation of Desire's machinations is that Desire acts simply from desire, and is as fickle and self-centered as the emotion.

Desire takes special delight in needling those who think they are beyond emotions altogether. It is, besides Death, the only one of the Endless that will point out Dream's faults, some of which are actually legitimate. Destruction noted that while Desire can be downright malicious, it isn't always wrong.

Dream
Desire has an openly hostile relationship with its brother, callously mocking Dream with his own shortcomings. A story in Endless Nights, set long before any other Sandman story, may explain the origins of the Dream's enmity and reveals that at one time, Desire was Dream's favorite sibling. Dream had fallen in love with, Killala of the Glow, and had taken her to a gathering of stars (literally the embodiment of various suns). While there, Killalla met and fell in love with the star of her own home world, abandoning Dream. Desire's role in this is obvious but never made clear. After introducing his lover to Desire when they first arrive and leaving the two alone, Killalla asked what Desire had done for Dream to make him so affectionate, but Desire indicated that it hadn't done anything at all. Later, however, when Dream angrily blames Desire for the whole affair, Desire offers no defense, only asking Destruction after Morpheus storms off, "Doesn't he have a sense of humor?" This story, set billions of years before the story-arc of The Sandman, tends to portray the characters in a very different light, showing that even the Endless are not unchanging.

The enmity between Dream and Desire continued through the millennia, eventually culminating in Desire raping and fathering a child on Unity Kinkaid, then attempting to have Dream kill Rose Walker, Unity's grandchild, which would have caused the ruthless and relentless Kindly Ones to hound Dream unto death for the crime of shedding family blood. When Dream discovers this at the end of The Doll's House, he openly threatens Desire should Desire interfere in Dream's life again, and there developed an uneasy truce between the two afterward.

Trivia

 * Desire is often referred to as "sibling" by its brethren, particularly Dream, thus avoiding the need for pronouns, although as the being is literally desire personified, 'it' has also been used as a personal pronoun.