Marius was born in Many, Louisiana, to Booker T. and Zelda Palmer McFarland. His father was a teacher and principal, and then superintendent of child welfare and attendance for the school board in Pine Flat and Many. His mother was an elementary teacher. Marius enjoyed working with cattle on his family's 10-acre farm. A member of 4-H, he also showed livestock. Marius held down several jobs. He cut grass for a local landscaper, cooked and waited tables at Stark's Restaurant, and worked at convenience and grocery stores. A musician, Marius played saxophone and keyboard at several churches. He recalls his boyhood as part of a "pretty comfortable life. We had air conditioning. We had plumbing. And we had all the amenities," he says. Unfortunately, his father was paralyzed in a traffic accident in 1976. The next year Marius graduated in a high school that was about 85 per cent white. He went on to Louisiana Tech, but transferred to Northwestern State University in Natchitoches. There he successfully auditioned for a spot in the Northwestern Entertainers, a musical group that played campus events and toured high schools in recruiting for the university. Marius was accepted into the LSU School of Medicine as one of four African-Americans in his class of 100. After finishing his intern residency at LSU-Shreveport he remained to teach medical students and residents. Six years later he went into private practice at Summit Hospital, spent a year as chief medical director, then returned to LSU-Shreveport as director of the walk-in clinic for one year. He then opened his own clinic in 1996, and has served as coroner for Caddo Parish. On May 29, 1986 he married Regina Ellison. They have four children.