Ja'far is an average sized man with pale skin, short white hair and black eyes. He also has freckles around his nose. He wears a long drabe that covers his entire body, and a green Arabian keffiyeh on his head. He always carries around his red wires, which is his Household Vessel, Bararaq Sei. When enraged, his eyes change into eyes that resemble those of a snake and turn gray. When Ja'far's hair is shown, it is always wild, as has been like this since he was young.
In certain instances, Ja'far's legs can be seen to be marked with two large, almost stitch like scars, which were originally confused with the jagged seams of his young assassin trousers in their first appearance. Since, recent art of Ja'far has cleared the buzzing debate and confirmed the canonical nature of the lines on his legs as scars, not to be confused with his attire as a child.
Ja'far is a serious person, who gets angry easily. He is most often the voice of reason when Sinbad is doing something outrageous. He tends to scold Sinbad a lot, despite Sinbad being his King, older, and stronger than him.
When provoked or angered, Ja'far shows a whole different side to himself. He was easily willing to kill Cassim when the latter opposed Sinbad. Another time this happened was when Judar called Ja'far a "small fry" and told him to step aside, because he had some business with Sinbad. Enraged, Ja'far was going to use his Household Vessel, Bararaq Sei with his full strength, but was stopped by Sinbad before he could do so.
Ja'far killed both his parents at the age of six and at some point joined and became leader of Parthevia's undercover unit, the assassins Sham Lash.
After the dungeon of Baal was conquered by Sinbad, Parthevia's Emperor ordered his troupe to track down and capture Sinbad, and take out Drakon if he became troublesome. The Emperor did not want Sinbad dead, but sought out the troupe because they knew sensitive information that the soldiers did not, and were excellent at dealing with combat. Despite the Emperor's wishes, Ja'far tried to assassinate him for unknown reasons. He failed in the assassination and, for reasons that are yet unknown, decided to serve him as a vassal. Little is known about Ja'far's history, but it is evident that, from a young age, he was under intensely abusive treatment, which would have most likely warped his ethical reasoning and his physical body. It is even shown that he was forced to kill his own parents.
Since his assassin days, Ja'far has apparently become quite tame and serious. Sinbad remarked that Ja'far's eyes were always rogue when they'd first met. Over the course of their acquaintance, Ja'far has apparently grown very close to his King, to the point where he is the only character to have nicknamed Sinbad, calling him always by "Sin." There appears to be a respect between Sinbad and Ja'far, as Ja'far was entrusted with the care of the entire Kingdom of Sindria while Sinbad was away.