Alianora's first appearance was in The Sandman #36, "Over the Sea to Sky".
As Dream unmade The Land, the entire population of Barbie's fantasy world gathers and enters the blackness of Dream's cloak to be absorbed into the Dreaming. A beautiful woman follows in their wake - Alianora.
New details regarding her story were revealed in The Sandman: Overture #3, in which Dream and another aspect of himself tell two versions of Alianora's tale.
Alianora is described to be very beautiful and majestic. She has long black hair and wears a white gown of a somewhat Victorian aspect, with long sleeves. There is a scar on her right cheek.
At one point, Dream's realm was invaded and taken over by two ancient gods, who held Dream prisoner inside his own castle. Powerless, he carved the sygils of his siblings on the walls of his prison, and asked them for help. Desire replied, and sent Alianora.
They battled and defeated the old gods together (from whose bones Dream would eventually carve the gate of his kingdom and his helmet), but Alianora was scarred during the battle, by the whip of scorpions one of the gods was carrying. The scar on her cheek foretold that Dream would receive his own scars, both physical and emotional, in turn.
As with the other women Dream had loved, his love for Alianora eventually faded, Dream told her she was free to leave his kingdom, but having spent too much time in dreams she knew waking up would destroy her, so Dream created a realm for her inside the Dreaming. Dream gave her a space of her own; an island at the edge of the Dreaming which would be entirely hers, and she could populate with creatures from her own imagination. If Alianora ever wished to leave it, she would have to smash the dreamstone which maintained the land, which would summon Dream who would then unmake the pocket world. (Overture #3)
She lived and eventually died in this place, and it passed to many other girls to use as a private escape. The pocket world was eventually unmade when Barbie, while under the control of the Cuckoo, smashed the dreamstone and called upon Dream. While he was unmaking The Land and absorbing all of the land's past inhabitants into himself, a remnant of Alianora reappeared, and the two shared a moment together before she too was absorbed. (The Sandman #36)
Being the recipient of one of Dream's 12 Dreamstones, the Rose-Quartz, implied Dream held her in high regard even after he no longer loved her.
Years later, the ghost of Alianora attended Dream's funeral, and was seen making a speech to the crowd of mourners; though the reader is not actually made privy to what she was saying. (The Sandman #72)