Dominus, a massive, highly advanced sentient computer complex created by the alien race known as the Arcane, planted itself in the American Southwest in order to prepare the way for a complete takeover of Earth. Needing agents for its dark purpose, it created the aritificial lifeforms Butte, Cactus, and Gila, but maintained only one human agent-- Sunstroke. Sunstroke claims to have “created himself,” and his true nature and origin remain a mystery.
The Avengers stumbled across Dominus' minions and were ultimately confronted by Dominus itself, who tricked the Avengers into becoming trapped in the past via a malfunctioning time machine. The Avengers nevertheless managed to return and confront Sunstroke and an army of multiple lifeforms. The dozens of lifeforms were destroyed, and Dominus nearly succeeded in putting the Avengers under his thrall if it were not for the multiple personalities of Moon Knight. Dominus fled, launching itself into space, and Sunstroke disappeared.
Sunstroke was later seen among the villains attending a weapons expo hosted by A.I.M., briefly battling Captain America who had infiltrated in disguise. He later joined a new version of the Masters of Evil, organized by the Crimson Cowl. He was among their number when they attempted to blackmail the world with the threat of a weather-manipulating machine but were confronted by the Thunderbolts. Sunstroke was chosen to help the Crimson Cowl make her escape, along with Dragonfly and Moonstone, but he was quickly downed by Moonstone who showed her true alligience by turning on the Crimson Cowl. Sunstroke, with the others, was remanded to custody.