Omega-Xis hails from Planet AM, escaping its annihilation to settle on Planet FM. Branded a traitor, he flees to Earth after stealing the Andromeda Key—a weapon of planetary devastation. Brash and headstrong, he initially focuses solely on self-preservation and personal objectives. He frequently teases others, especially about romantic inclinations, and enjoys nature alongside detective shows, quoting them in missions.

Pursued by FM-ians, he crash-lands on Earth and merges with Geo Stelar via EM Wave Change, forming Mega Man. Leveraging knowledge of Geo’s missing father, Kelvin Stelar, he secures Geo’s aid. Early on, he scoffs at Geo’s altruism, challenging the logic of aiding strangers in conflicts. His AM-ian heritage remains unknown until fellow AM-ians on Earth unveil it.

Across the original series, he shatters the Andromeda Key twice, destroying it completely the second time. His bond with Geo mellows his demeanor, teaching him empathy and cooperation as Geo gains confidence. During the Andromeda crisis, he confronts FM-ian King Cepheus, forgiving him upon learning Cepheus was manipulated into annihilating Planet AM.

In the *Tribe* arc, he accidentally ingests the "Sword of Berserker" OOPArt during a museum clash, enduring recurring pain as residual EM spirits struggle to retrieve it. He dismisses this agony, masking it behind toughness even when contrasting it with Geo’s minor ills. This OOPArt grants temporary access to enhanced combat forms, though he never wields others like the "Star of Shinobi" or "Rock of Dinosaur." He fosters a one-sided rivalry with Acid, seething when Acid acknowledges Geo but ignores him, and bristles at encountering his own clones during a WAZA assault.

His powers encompass EM Wave Change—fusing with Geo to become Mega Man—and Wave Conversion, transmuting humans into EM waves for survival. As a materialized Wizard, he unleashes physical strikes like Beast Swing and Area Eater. Like all EM beings, he resists hypnosis and external control.