The glaring contrast and fierce struggle between the two worlds of Stanley Kowalski and Blanche DuBois are the main themes of Williams' play. These two worlds are so diametrically opposed that they can never meet. Thus, in order to bring these two together — to have these two encounter each other — Williams has created Stella. By simply having her married to Stanley and by having her be Blanche's sister, Williams then creates the perfect opportunity of bringing these two opposing worlds together under one roof.
Stella DuBois Kowalski is, then, a vital part in the struggle between these two worlds, and she is also the bridge between these two worlds. Both Blanche and Stanley are guilty of trying to involve Stella in their quarrel. Both attempt to win Stella over as an ally. Stella is the battlefield for those two warring factions, and both try to use her to accomplish their own ends. But Stella also seems to be the only answer to peace, for she is the only bridge between these two apparent opposites. She comes from Blanche's refined, educated, and sensitive world. She has, therefore, attained a mixture either consciously or unconsciously.
