Bianca is Cassio’s lover, who plays an essential role in the play’s tragic development. She participates in Iago’s scheme against her will, helping Othello believe that Desdemona is dishonest. In love with Cassio, Bianca is jealous of him, suspecting him of cheating.
In Scene 1 of Act 4, Iago and Cassio discuss sexual exploits with Bianca. They are berating her for her feelings and devotion, with Cassio refusing to marry her:
I marry her! What? A customer! Prithee, bear some
charity to my wit: do not think it so unwholesome.
(Act 4, Scene 1)
Othello overhears them, thinking that they are talking about Desdemona. He is overwhelmed with rage and jealousy, incapable of seeing reality.
Then Bianca enters the scene with Desdemona’s handkerchief. She throws it at Cassio’s feet, confirming Othello’s suspicions:
Let the devil and his dam haunt you! What did you
mean by that same handkerchief you gave me even now?
I was a fine fool to take it. I must take out the
work? A likely piece of work, that you should find
it in your chamber, and not know who left it there!
(Act 4, Scene 1)
This scene is the turning point in the plot development. Bianca works like a tool in Iago’s plan, which leads to an unfortunate result. It proves Othello’s suspicions and makes him desire to murder Desdemona and Cassio.
Bianca is portrayed as an archetypal vulnerable woman. Treated like a sexual object, she depends on men and is abused by them. She is a prostitute looking for love, which she foolishly thinks Cassio can give her. He promises to marry her but treats her without respect and keeps their relationship hidden. Besides, Cassio berates her behind her back.
Bianca is often compared with the characters of Desdemona and Emilia. Her sincere feelings towards Cassio can be compared with Desdemona. Yet Emilia’s cynical conformity to social norms is paralleled with Bianca. As the only unmarried woman in the play, she doesn’t officially belong to any man. Free to leave her lover at any moment, she is more liberated than any other female character. Despite her low social status and reputation, Bianca has more freedom.
Her unfounded jealousy mirrors Othello’s grudge. However, unlike him, Bianca has no power to take action and lacks wicked plans for revenge.