When Aioros was 14 years old, he, along with fellow gold saint Gemini Saga, were summoned to Pope Shion's throne room for an audience. There, the Grand Pope revealed that their goddess had once again reincarnated in the form of an infant, and so the Sanctuary must prepare itself for the imminent wars. As Shion himself was getting on in years, he decided that it was time to appoint one of the twelve Gold Saints as the successor to his seat. At the time, most of the Gold Saints were still too young; only Gemini Saga and Sagittarius Aioros were most qualified. The Pope eventually selected Aioros as the new Pope, and asked Saga to serve as an assistant to the Sagittarius Saint.

Saga, possessed by his evil side, became jealous at the fact that he was not chosen for the seat, especially since he believed that he was superior to Aioros in terms of power and wisdom. Saga confronted Shion regarding his decision and killed him. He disguised himself with the Grand Pope's garments, and left to kill the infant Athena. Inches before Saga could dig the golden dagger into the baby's belly, Aioros appeared and halted the blade from striking the death blow. The Sagittarius berated the man he assumed to be the Pope, but was quickly shoved aside. After a minute of struggle, Aioros sent Saga flying into the nearest wall, knocking off his headdress and mask. Upon seeing Saga's face and realizing that Saga had killed the Grand Pope, Aioros immediately snatched away the infant Athena and ran off from Sanctuary.

Saga, disguised as the Pope once more, sounded the alarm and sent guards to go after the saint. It is at this point that he officially branded Aioros as a "traitor." He was eventually found by Capricorn Shura and managed to flee, but was deadly injured.

As he was dying, he ran into Mitsumasa Kido, who was touring Greece at the time. Aioros begged the elder Kido to become Athena's new guardian, and explained to him the travesty that had taken place at the Sanctuary. Along with other secrets, Kido learned about the existence of Athena's Saints and their Cloths. Entrusting the elder Kido with Athena and his own Sagittarius Gold Cloth, Aioros succumbed to his injuries. It is unknown as to where exactly Aioros died and buried, as the whereabouts of the location is omitted in the series.

After his death, Aioros' spirit would provide assistance for Athena and her Saints. He has aided Seiya in battles by lending the young bronze saint the Sagittarius Gold Cloth time and time again, and even appeared once to his brother Aiolia during Aiolia's fight with Seiya, when he demanded proof of Saori's identity as the goddess Athena. When the bronze saints were in the Temple of Sagittarius, the Sagittarius Cloth moved on its own (or with Aioros' spirit), and fired its golden arrow into a nearby wall—revealing a final hidden message of the gold saint's last will: "To you young boys who have reached this temple, know that I entrust Athena's life in your hands. Aioros." It is likely that Aioros foresaw that one day, new Saints would go to his temple to fight for Athena.

When Athena's saints were once again fighting against Hades's spectres, all the Gold Saints, both dead and alive, gathered in Hades' room to break the Wailing Wall. Only with sunlight can the wall be destroyed, and because each individual gold cloth contained a bit of solar energy, gathering all twelve would provide enough of it to properly damage the wall. At this point, the spirit of Aioros appeared with the rest of the recently deceased Gold Saints to aid their comrades in accomplishing this task. Focusing on a single point of the Wailing Wall, Aioros guided all twelve gold saints' individual attacks into one, and struck the wall. Once the mission was completed, Aioros and the rest of the gold saints dissipated, leaving only the gold cloth behind.

Although Aioros' moves were not shown in the original manga, there are nevertheless two techniques that were attributed to him in other mediums: one in the anime adaptation, and another in Episode G.

They are:
- Atomic Thunderbolt (atomikku sandāboruto): Aioros shoots a massive amount of energy balls with some electric charge. This attack is from the anime, and was revealed during a flashback fight against Capricorn Shura.
- Infinity Break (infiniti bureiku): This technique allows Aioros to shoot an infinite number of light darts that pierce anything upon contact. With this attack, Aioros destroyed Horus' army in Saint Seiya: Episode G.

Aioros' cloth, Sagittarius Cloth, is armed with a bow and a golden arrow. This arrow is often depicted as the main weapon of the series and gives the final blow in four of the five movies of the series when is used by Pegasus Seiya. It was hinted on the original series and confirmed in Saint Seiya Episode G that the golden arrow can concentrate the Cosmos of those surrounding it if they wish.

Even though most fans recognize his given name as Aiolos, the true intention of Masami Kurumada was to name him Aioros, a Japanization the name of the Greek god of the winds Aiolos. This can be confirmed in vol.11 of Kurumada's manga, in Aioros' testament. Kurumada drew capitalized Greek letters spelling the character's name as Aioros: ΑἸΟῬΟΣ. He clearly used a "R" instead of an "L," in the spelling of the name. If he had wanted to spell it Aiolos, he would have drew them as: Αἴολος or ΑἸΟΛΟΣ. Some attribute the discrepancy to the fact that in Japanese, the letter "L" doesn't exist, and is replaced by the letter "R" in foreign words. The fandom in general is mostly familiarized with the more "Greek" spelling, Aiolos, though in some languages, such as in the Latin-American Spanish dub of the anime, the arguably more Kurumada-accurate "Aioros" is used.

As revealed by Masami Kurumada in vol.12 of his manga, Aioros became a Gold Saint at an early age. He had already been granted the Gold Saint status and the Sagittarius Gold Cloth before the time he was 14 years old.