S/he is the third youngest of the Endless. Desire is a beautiful, perfectly androgynous figure who is not so much genderless as multiple-gendered. Desire blends in effortlessly with whatever environment she finds himself in. Desire smokes, and smiles a lot, though in a way entirely different from Death. Desire lives in a massive statue of herself, known as the Threshold. His sigil in the galleries of the other characters is a glass heart.
Desire is easily the cruellest of the Endless. Desire seems obsessed with interfering with the affairs of her elder siblings, particularly Morpheus. The motivation behind this is not clear, but seems to be simply a variation on childish teasing. Desire is not exactly unaware of the consequences of his actions, but considers those consequences ultimately unimportant, a position which angers Morpheus and Death in particular. Desire is the twin sibling of Despair, and the two sometimes act in concert; the relationship is not clear, however, and Desire is much more distant from her siblings than Despair.
Being perfectly androgynous, Desire makes the family line up of the Endless perfectly symmetrical. As well as having seven memebrs (the perfect number), by virtue of his gender, she manages to allow the Endless to contain both four males, and four females.