Bianca (Othello) confirms his wife's infidelity. This "evidence" completes Iago's manufactured case against Desdemona, and thereafter Othello is determined to murder both her and Cassio. In 5.1, Bianca arrives just after Cassio has been stabbed by Iago. She reacts with horror and concern. Iago, pretending to have just entered the scene, accuses Bianca of having been part of the group that attacked Cassio. Iago claims her emotional reaction is due to her being caught rather than concern for Cassio and gets her to admit that Cassio ate at her home earlier that evening. Both Iago and Emilia call her a prostitute, but
Emilia (Othello) mention in the source of the ensign's wife being Desdemona's attendant. In Cinthio, the ensign's wife accompanies her husband to Cyprus. She is described as "a beautiful and virtuous young woman" who, "being of Italian birth...was much loved by the Moor's wife, who spent the greater part of the day with her." The ensign, "not heeding at all the vows he had made his wife", lusts after Desdemona who, very much in love with the Moor, is oblivious to the ensign's passion. In Cinthio, the ensign filches Desdemona's handkerchief when she visits his house and hugs his three-year-old daughter. It