The Blood Brothers are large twin ape-like aliens called Roclites originally in the service of the mad Titan Thanos, acting as the guardians of his first base on Earth. When Iron Man receives a mental signal sent by an imprisoned Drax the Destroyer, he becomes a target for the Blood Brothers, who ambush him and take him to Thanos' base where Drax is being held. When the two heroes overpower the brothers, Thanos detonates a explosion, forcing the heroes to flee, leaving the Blood Brothers behind. When Thanos later obtains the Cosmic Cube, Iron Man returns to Thanos' base to search for him, and is taken by surprise by the Blood Brothers, who are still alive, and remain loyal to Thanos. They attempt to kill Iron Man, but he and the Thing, who saw Iron Man's flight overhead and followed him to the base, overpower the Blood Brothers. With the henchmen defeated a second time, Thanos teleports the Blood Brothers to an unrevealed location.