Killala of the Glow is an ancient Oan who was one of the first of her race able to manipulate a glowing green force called "The Glow" with the power of her mind.
A Maltusian ancestor of the Guardians of the Universe (founders of the Green Lantern Corps), it is by experimenting with her new Glow abilities that she makes contact with the Dreaming and Dream. Dream falls in love with Killala, and the two start a whirlwind romance that consumes Dream's whole attention.
It is during a meeting of great Universal manifestations that Desire, Dream's sibling, starts to play and influence Killala who then falls in love with Sto-Oa, who is the sun her planet orbits around.
Killala comes to learn the truth that the beings that surround her are not mere aliens, but the raw living spirits of the Universe. Terrified of what she learns she retreats through the use of the Glow into the arms of Sto-Oa. They are seen by Dream in an embrace, and remain together until her own light ends and is then embraced by Sto-OA for eternity.
Desire's manipulation of Killala and Sto-Oa ended whatever affection and friendship Dream had for his sibling.