Aa of the Pumice People of Stoneworld was one of two recruits chosen for the Green Lantern Corps by Brik of Dryad. The other recruit, Kworri, was from the Obsidian-Folk of Stoneworld. Before they could travel to Oa, they were captured along with Hal Jordan by the mercenary known as Flicker. The Green Lanterns were brought to Pan-Galactic Placement Services, to be sold as slaves to fight in an interstellar war.
Jordan decided the Green Lanterns would track Star Sapphire. This caused dissent between the two recruits. Aa wished to serve the greater good, and did not wish to go on Jordan's personal quest. Kworri, who was Aa's rival, offered his unfailing loyalties in whatever mission they would undertake. Jordan decided he would give the ring to the better of the two candidates.
Kworri stood ready, but was sent back to Stoneworld by Jordan. Although Kworri had been loyal, Jordan wanted Green Lanterns who could question others, and override their decisions if necessary. Aa would be the new Green Lantern. For his heroic actions in trying to prevent the war, the chieftain of the Teban battle-dhow, Kreon, was later made a Green Lantern.
Aa finally left the Green Lantern Corps after a battle with the incarnation of Entropy. The Green Lantern Corps had once again been divided in its choice of action, whether to fight an impossible battle with Entropy or surrender to it. Aa could not base her life on faith and unprovable cosmic predictions. She would search for answers on her own.
She later chose to join the Darkstars. Aa believed in serving the Controllers rather than the Guardians because they did not ask Darkstars to believe in their omniscience. The Controllers asked the Darkstars to protect planets, leaving them free to seek their own answers. Aa was given a means to patrol the cosmos and paid for it with her deeds.
During the return of the Maltusian Gods, The Triarch, Aa fought her former Green Lantern teammates. Despite her change of teams, Jordan was still impressed with Aa, and had not given up hope of bringing her back as a Green Lantern. .
Years later, following Hal Jordan's release from the control of Parallax, Aa would join the restored Green Lantern Corps. She and Lanterns old and new took part in the massive battle against Superboy-Prime.