Marcos is a brown and gray wolf with brown hair and blue eyes. He wears a blue and white bodysuit with gold and blue wristbands and, unlike most of the wolves, boots rather than sandals. In earlier appearances, his gray fur was much darker.
During the First Robotnik War, the wolves of the Great Unknown drew lots to decide who would fight and who would stay behind to protect the others; Marcos's mother Lupe Wolf left to form the Wolf Pack while his father Lobo stayed behind with Marcos and his sister Maria. Unfortunately, at some point all three were captured and roboticized. When Lupe's pack returned to the ruins of their city, a roboticized Sir Charles Hedgehog forced her to also submit to the process lest her family be dismantled.
Eventually, all Robians, Lupe's family included, had their free will restored, and so the roboticized Marcos accompanied his family to Knothole Village where Lupe forgave Charles for his uncontrolled actions. Later, the whole family was restored to their true forms by the Bem; after celebrating, they left to resume their journey. While in the woods they were nearly caught up in the spread of A.D.A.M.'s nanites; too small to run quickly enough, Marcos was carried by Canus. The group escaped and continued traveling.
Settling in a New Home
The scattered wolves were eventually resettled in the southern hemisphere, forming the new Wolf Pack Nation. Though hostilities arose between the wolves and the Felidae, who apparently kidnapped Marcos and his siblings before they came back home. When Sally Acorn and Sonic the Hedgehog arrived in response to an invitation to be inducted as members of the Pack, they witnessed Marcos running from his three sisters after taking their toy ball. When Maria demanded it back, Marcos insisted that Athena said he could have it; when Aerial pointed out that Athena, as Marcos should know, is mute, he tauntingly replied that she talks more than enough for her, causing the girls to lunge at him. Lupe dryly commented that the children were more difficult to govern than the nation itself. Not long afterwards, a scared Marcos and Aerial ran to their mother to warn of what seemed to be a Felidae warrior in their city.
Marcos comes off as somewhat vivacious and mischievous, often teasing or getting into squabbles with his sisters. Despite this, he truly loves his family, including his adopted sisters, caring greatly about them, their people, and their home, especially in regards to their coexistence with the Felidae.