Marcel Guilbeau and his brother Jereaux Guilbeau grew up in a mid-19th century plantation south of Baton Rouge Louisiana. He eventually grew to idolize his brother and when the US Civil War broke out he enlisted for the Confederacy, hoping to serve in the same unit with him. Instead, Marcel grew sick and Jereaux went to war without him in Tennessee. When he recovered, Marcel was sent east where he eventually joined Jeb Stuart's cavalry.
Marcel returned home first and worked to rebuild his family's plantation. When his brother finally came back, he had been embraced and brought with him a vampiric master. After a few days, Jereaux's sire Lothar Constantine embraced Marcel as well. Jereaux quickly began mentoring his brother, acting as a kind of surrogate sire and distancing both broodmates from Constantine. Eventually Jereaux would leave with his sire and return with a change of clothes. Constantine would never been seen or heard from again.
The brothers then moved to New Orleans where Jereaux posed as Marcel's sire and began making political connections. Jereaux ensured that Marcel became a member of Prince Doran's spy network and when Doran was mysteriously murdered, he encouraged his brother to make a bid for prince. Within a few nights, with the help of blackmail acquired through years in the former prince's spy network, Marcel became prince of New Orleans.
Jereaux then disappeared from Kindred society, instead becoming a silent mentor and guide for his brother's reign. Few major decisions are made without Marcel going back to the family farm and consulting with his brother/mentor. Whenever a major threat is uncovered through Marcel's spy network, Jereaux goes out and takes care of things himself, leaving the Prince's hands clean.