Ezra Jennings is a tragic figure on the margins of the Victorian society depicted in The Moonstone. His strange appearance seems to define him for others and encourage their social rejection of him. He is tall and gaunt, with a wrinkled face that makes him seem older than he is and hair that is black on top and white on the sides. Jennings's character seems to relate to the larger theme of English interaction with colonial peoples, in that Jennings is of mixed parentage and was raised in a colony. Unlike Mr. Murthwaite, who poses as an Indian but is stolidly English inside, Jennings's truly possesses some of the more mystical and exotic characteristics of the Indians—Jennings's "dreamy eyes" are mentioned more than once. Jennings' opium addiction is related to his status as a part-colonial subject (opium having originated in the East).

Like Franklin Blake, his respectable Victorian counterpart, Jennings encompasses several contradictions. His capacity for dreaminess and imagination is countered by his status as a representative figure of objective science. Jennings is an aspiring doctor and researcher. He meticulously uses respected sources and experimental techniques to prove Franklin Blake's innocence. Jennings is related to Blake in that, earlier in his life, he has been accused of a crime he didn't commit but could not prove his innocence. He is thus a tragic figure, roaming around England to escape malicious gossip. In this sense, he represents what Franklin Blake might have become, if he could not clear his name. By the end of the novel, Jennings dies of the disease he has staved off using opium for years.