Bio: Living in Santo Marco, Acero's brother Jorge was killed by The Weapon X Project's adamantium cyborgs they had developed in hopes of wiping out mutant kind. After the team of Weapon X investigated the death of Jorge, Warpath gave Acero his number in case he ever needed to reach them.
The President of Santo Marco, Emilio Duarte, a mutant hating dictator, soon after deployed his Nuke Platoon (soldiers amped up on Nuke Pills) to rid his country of all mutants and their allies. Acero called Warpath and Weapon X came to their aid.
After defeating the Nuke Platoon, Acero led the revolution against President Duarte, who was killed by the original Nuke (Frank Simpson) just as the revolution was reaching the Presidential Palace. Weapon X left Santo Marco in the hands of Acero, hoping that it could finally find peace.