When Miss Julie (played by Saffron Burrows) comes downstairs we see that she is taller than Jean. She is a bold woman who has learned how to handle men. She has come for some entertainment with the servants because she is bored with the rich.
Her fiance left her because she was too strong. She is angry - and rebounding, appearing to be interested in being reckless. She engages in an emotional duel with Jean, trying to engage and yet repel him. Each one seems to want to prove that they would never have the nerve to become intimate. This is because it would be forbidden due to the rules of society.
They really do not like each other, yet remain attracted. Their dislike seems to be an aphrodisiac. Therefore, they are willing to put themselves in danger. The situation creates a level of tension that is palpable. The verbal drama that ensues only seems to spark the fire more.
There is much sadomasochism in their involvement. At first, she attempts to make him grovel at her feet, given that she is taller than him. Ultimately, he takes the upper hand by letting her know the harsh and unflattering truth about herself. By the time they actually have sex, it is more like a coup than anything sensual. The game seems to be that they both are set upon destroying each other.