Jerome has short black hair and appears to be in his early to mid thirties. He is of average height compared to the other knights.
Jerome, although being a member of the Holy Iron Chain Knights, was a fairly decent person and in private admitted to disliking his job. He was known to enjoy sex, and spent many of his breaks and much of his money on prostitutes, though he held a special place for Luca in his heart.
Though he enjoyed his life's comfort and was shocked and scared by the happenings at St. Albion, he resolved to defy the Knights in order to protect Luca.
He is one of the only four members of the Holy Iron Chain Knights to survive the arrival of Griffith into the material world (the other three being Farnese, Serpico and Azan).
Jerome is introduced alongside Luca, with whom he is seen having sex until the unfortunate arrival of "Elaine" (Casca) which scares him limp and ruins the moment. Following this, he makes known his attitude towards the heretic-hunting, pays Luca in full along with supplying her a pearl necklace, promises her a place in his future household as a mistress even though he is expected to marry a noble, and offers Luca's "sister" Elaine, apparently afflicted with syphilis, a safe place as well.
Later, he shares a moment with Serpico, where he addresses again his disgust with the Knights' executions and hears Serpico's story. Jerome later gets separated from the Knights along with Serpico and Farnese, and spends the rest of the arc alongside them as a bystander and occasional fighter.
After St. Albion, it is heard from Luca that Jerome married a noble woman, but that the prostitute did not take Jerome up on his offer due to feeling guilty about deceiving his wife, who she considered sweet but naive. It is unknown if Jerome left the Holy Iron Chain Knights or not at this point.