He was the second husband of Julia Avita Mamaea and step-father of the future emperor Severus Alexander.
[1] Cassius Dio mentions a daughter that was married in 218 AD,[1] thus probably a child from a previous marriage than the one to Mamaea.
[2] Mamaea was the second daughter of the powerful Roman Syrian nobles Julia Maesa and Julius Avitus.
[2] The marriage of Marcianus and Mamaea may have strengthened Septimius Severus' power base in the Roman Eastern provinces.
[6] He was murdered on the orders of Roman emperor Macrinus in 218[1] in Emesa, Syria alongside an unnamed daughter and son-in-law.