Jean is a valet who lets himself go during a night of Midsummer's eve carnival and bacchanal. He is a conflicted person who both dreams of rising up the class ladder and becoming an aristocrat but who, in his heart of hearts, has a servant's mentality and can't really conceive of changing his life.
During this night of freedom in which Miss Julie crosses class lines, including insisting that Jean dance with her, he confides in this upper-class woman, to whom he is usually subservient and pretends to be a kinder person than he really is. He tells her that he fell in love with her when they were children. He thought of her father's garden as a paradise and became ambitious to become an aristocrat. He informs her that he dreams of going to Romania, where it is possible for a person to buy an aristocratic title.
Although Jean sleeps with Miss Julie and talks of running away with her to Lake Como, he also despises her for having no money, crossing class lines, and sleeping with a person like him—even going as far as calling her a whore. He continues to put up with her volatile personality, however, and continues to do her bidding. For example, he decapitates her canary when she tells him to kill it. In the end, for all his talk and ambition, Jean still plans to marry a servant, and when Julie's father, the Count returns, Jean immediately resumes his servile role. He is a stronger person than Miss Julie and may have a chance to rise in the world, but at the same time he is hampered by his servant's training.