Mark and Marcellian were brothers of noble Roman birth. Though they converted to Christianity as boys, their families remained pagan. They later they each married, but their wives and children remained pagan.
Under the persecutions of Emperor Diocletian they were arrested and put in prison. They were instructed to sacrifice to the Roman gods or parish. Friends intervened, obtaining a 30-day liberty for the men, confining them to house arrest.
Despite the pleas of family, they still refused to pay homage to the Roman gods. St. Sebastian, a Roman soldier, who later would be martyred for his faith, visited them several times to encourage them in maintaining their Christianity. In fact, their faith was so great that they converted their guards who, breaking orders, set them free. Ultimately, they were recaptured and put to death.
Adapted by A.J. Valentini from www.franciscanmedia.org