Saul is not an Elbaf giant despite being large in size. He was born outside of Elbaf and has experienced travel throughout the Grand Line, though little information about his adventures is known other than meeting Devil Fruit users. As a Marine, he eventually rose to the rank of Vice Admiral before the story began. Saul's personality is characterized as shy and timid, but also loyal to the Marines. He questioned orders at least twice, indicating that he followed moral justice over their code of absolute justice. Saul has an awkward laugh ("Dereshishishishi") which he finds somewhat embarrassing. He enjoys seeing others have fun and encouraged Robin to laugh as well.
Saul is one of the three people who influenced Nico Robin, and he wears a cowboy hat that Robin later adopts for herself. Saul's middle name explains how Robin knows about the Will of D, which she tells Luffy later on why he should fight. Saul had a good friendship with Vice Admiral Kuzan (later known as Admiral Aokiji) and shared their view on moral justice. The reason Kuzan allowed Robin to live was likely due to a final favor to Saul.