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.
[Green Lantern Vol. 3 #20-#21]
The Green Lanterns managed to escape from Flicker and his crew. Aa had captured a prisoner before Flicker's ship made its own escape into warp. Scanning the prisoner's mind, they learned Flicker had captured Star Sapphire, Hal Jordan's old love and now enemy. She had been sold to the Teban military as a weapon.
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.
[Green Lantern Vol. 3 #21]
Kworri and Aa were made temporary Green Lanterns, as Hal Jordan had to answer a distress call from Earth. With Brik, they had tracked a Teban battle-dhow to a skirmish with the Quahooga. Aa wished to engage in battle, Kworri and Brik believed they should wait until Jordan's return.
Jordan's arrival signaled the attack on the Tebans. Flicker had planted information leading Jordan to Star Sapphire, hoping to capture him once again. The Green Lanterns were at a stalemate with the mercenary. If Jordan did not surrender his ring, Flicker would kill Star Sapphire. Aa used her ring to distract Flicker, who misfired. Aa's rash action, though it endangered Sapphire, allowed Jordan to fight back against Flicker. With Teban reinforcements approaching, the four Green Lanterns escaped, bringing the imprisoned Star Sapphire with them.
Far from the Tebans, it was time to choose which of the recruits would the new Green Lantern. 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.
[Green Lantern Vol. 3 #22-#24]
Kilowog became Aa's trainer, the new Green Lanterns would learn tales of the Corps' past. She had been searching for answers from the seemingly superior races of the Corps, but instead found confusion.
[Green Lantern Corps Quarterly #1, #3]
On Oa, Aa witnessed Kreon and Boodikka fighting among themselves rather than the invading Weaponers of Qward. The Guardians of the Universe themselves were at risk from the Weaponers, as the Green Lantern Corps were on the verge of defeat. Surprisingly, the ex-Green Lantern Guy Gardner repelled the invading forces. Gardner had been working with the bounty hunter known as Lobo and had been responsible for bringing the Qwardians to Oa in the first place. Although the invasion was not Gardner's intent, he used the diversion to take Sinestro's yellow power ring.
[Guy Gardner Reborn #2-#3]
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.
[Green Lantern Vol. 3 #34-#35]
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.
[Green Lantern Vol. 3 #45]
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. Her opinion of Jordan's transformation to the being known as Parallax and her current activities are not known.
[Green Lantern Corps Vol. 3 #45, L.E.G.I.O.N. #58, Trinity #2]
As a Green Lantern Aa's principal weapon was the Green Lantern power ring she wore on the middle finger of her right hand.