Marlon is a gang member in Turk's crew and Kelly Severide’s archenemy. He and the gang overran Firehouse 51 while ducking a drive-by crew out to off them. He was shown to be a ticking timebomb and lost his cool to some degree. When Ambulance 61 was about to return back, Matthew Casey waived them off to keep them from entering and Marlon shot him in the shoulder. He was later overwhelmed by Kelly Severide and Stella Kidd and later arrested by Chicago PD SWAT. He was a skilled fighter, as he was able to stand up to Severide in both their fights and would have killed him if Kidd had not caught him off guard.