Have you ever spent days and days making up flavors of ice cream that no one's ever eaten before? Like chicken and telephone ice cream?...Green mouse ice cream was the worst. I didn't like that at all.
Delirium, known to ancient Greeks as Mania, is the youngest of The Endless. She is usually quite short and thin, and looks no older than a teen-age human girl. One of her eyes is blue, and the other is green, though she can adjust them to the same color but says that hurts her. Her hair changes style and color constantly, as do her clothes. Her shadow never reflects her shape, and is tangible, like velvet. She is said to smell of sweat, late nights, sour wine, and old leather. Her sigil in the galleries of the other Endless is a multicolored, abstract swirl. Her realm is a chaotic, constantly changing mass of colors,strange objects and shapes, and contains a sundial with the inscription "Tempus Frangit" ("time breaks," a Latin pun on the phrase "Tempus Fugit", "time flies"). After the events of Brief Lives, Delirium travels with a companion, a dog named Barnabas, on permanent loan from her brother Destruction.
Delirium never has a consistent appearance. Often both her hair and clothes shift from minute to minute with the only things being relatively consistent is her multi-colored hair and eyes.First incarnated as Delight, she eventually transformed into Delirium for reasons even Destiny does not know. She can be seen as a very young Delight in Endless Nights; and in Overture she is seen at the beginning of her change from Delight to Delirium. A statue of her as Delight can be seen in Destiny's garden in Brief Lives, and her official portrait in Destiny's gallery depicts her as Delight, not Delirium, in Season of Mists. She is scatterbrained and easily distracted; she often forgets the thread of her conversations, and comes out with offbeat and seemingly inconsequential observations.
Todd Klein, the series' letterer, draws her speech as a scrawl, against a multi-colored background, sometimes the background color will match the mood she is in (red for anger, blue and green for calm, etc.). Very occasionally she is able, with an effort, to become more controlled in thought and speech, at which point her speech is drawn more neatly and the background fades to near-white. This effort, as she says later, causes her pain. Her speech as Delight in Endless Nights takes the same form, with somewhat orderly lettering and a faint rainbow background.
The other Endless, particularly Death and Destruction, seem to be fond of Delirium, to varying degrees, and protective of her. She in turn is affectionate towards them, particularly Destruction. She originally was somewhat frightened by Dream and avoided being around him (to the point that his guardians did not know who she was), however, the events of Brief Lives change their relationship. Delirium desperately tries to help save Dream from his impending doom in The Kindly Ones by trying to persuade him to go with him on another quest with her to find Barnabas, but Dream refuses.It has been implied throughout the series that Delirium is the wisest of all the Endless knowing more than even Destiny. Delirium implies what Death describes that anyone knows everything but chooses not to, which leads to madness as she "explains". Delirium also grasps what Destruction stated during his abdication, that the Endless define two sides, when she becomes sane and ordered before Destiny. Delirium has brief outbursts of insight and prophecy that often surprise those around her, and more often than not are ignored.
Delirium often has a playful attitude, regarding some events with ecstatic joy, such as being held above the ground by the Wyvern, to Destiny splitting into multiple incarnations before her. Delirium is also is quick to respond angrily to rudeness, leading her to occasionally punish people with madness and without mercy.