Marcos Eringrad Garcia is a sixteen-year-old Mexican immigrant from the cartel-dominated northern region of Gran Mexico. He was raised by his mother and knew very little about his father, aside from the fact that he was a gangster. At the age of six, he met Alex Kandley Stewart at his mother's former workplace, and later became close friends with Sheila Levitt. Plagued by poverty, Marcos held many part-time jobs but often skipped work shortly after payday. Together with Alex, he fled Mexico for the United States, hoping to find honest work and reunite with Sheila. Seeking a better life and American citizenship, he joined the Annex Project and underwent the M.O. Operation, receiving a genetic modification based on the brown huntsman spider. This transformation granted him immense strength, ferocity, and extraordinary speed that surpasses the Terraformars, allowing him to dodge and even catch bullets. His endurance is remarkably high, enabling him to fight without rest until his serum expires. In combat, he wields a staff he calls the Archnebuster Mk.II, which he uses to deflect ranged attacks and impale his enemies, though his friends often mock the name for sounding like it is meant to defeat spiders rather than cockroaches. Marcos tends to be calm and composed under pressure, acting as a mediator among his more hotheaded teammates. He is deeply loyal to his comrades and motivated by a fierce determination to protect them and never give up, a sentiment he extends to all the soldiers and non-combatants on Mars. Over the course of the story, he proves himself a reliable and capable fighter, maintaining a disciplined focus on the mission while valuing the well-being of those around him.