The play opens with a conversation between Iago and Roderigo. Roderigo is obviously upset with Iago, thinking that Iago knew about a certain incident occurring and didn't tell him. We don't know what event or incident Roderigo is referring to, so we listen further. As we listen like eavesdroppers, we hear Iago attempting to placate Roderigo, joining him in his anger, but redirecting Roderigo's anger against some else who has overlooked Iago for a promotion to the rank of Lieutenant. The audience now is beginning to put pieces of information together. This beginning in medias res provides suspense and confusion. We begin to realize that the one both men are angry with is Othello, and we see Othello in a very negative light. Iago calls him pompous, "horribly stuffed with epithets of war," and even somewhat stupid in choosing an unexperienced man like Cassio to be his lieutenant. Do we believe Iago here? And yet, we are also given a look into Iago's warped mentality with his declaration, "I am not what I am," as he boasts that he will undermine Othello by pretending to be his loyal servant.
Already we see characters pitted against each other, and we have probably as yet not chosen sides. We may even sympathize more with Iago here since we all know what it is like when a job goes to someone less qualified than ourselves. But then the next step the two take is to go rouse her father. More confusion is created for the audience as the two men race to wake up the sleeping Brabantio with horrible obscenities describing Brabantio's daughter's elopement to Othello. This coarse language is certainly attention-getting and also bewildering. Once again we are given negative images of Othello as a beast-like, sex-crazed black man. And, a third man, Brabantio, is now angered and desperate to stop the marriage. Another bit of information is now given to us--Roderigo had wanted to marry Desdemona, Brabantio's daughter.
Now,we are ready to read on to see what kind of man Othello is and how he will be able to handle those who feel they have been wronged by him: Roderigo who wanted to marry Desdemona, Brabantio whose daughter was stolen from him; and Iago who was denied a promotion. By beginning in the middle of a conversation followed by angry shouts and crude language, Shakespeare creates tension and confusion. We are given information bit by bit, and are anxious to see the showdown that must surely come.
The nighttime setting of the scene certainly allows Iago and Roderigo to rouse Brabantio from his sleep all while concealing his identity. Because Brabantio cannot see Roderigo clearly, at first he doesn't even know who has been so rude as to wake him. Additionally, when Roderigo is not stirring Brabantio into a rage over Desdemona as Iago had commanded him to do, Iago begins shouting out information to Brabantio, all while remaining out of sight.
If the audience puts itself in Brabantio's place, it is easy to see how a half-awake father would be confused and swayed by two "partyers" outside his house in the middle of the night. Also, Iago slips into speaking prose (rather than in the cultured verse style that he normally uses) so that he will appear to be a crude commoner--this helps to confuse the nobleman even more.
In regards to the tension in the scene, there are two primary examples. Iago and Roderigo are not on the best of terms at the beginning of the scene because Roderigo discovers that "his" Desdemona has just married another man, and his cause seems lost. Iago must persuade Roderigo that he has his best interest at heart and that he will help him "win back" Desdemona. The other example of tension is between Brabantio and Roderigo. When Brabantio discovers that the rowdy person outside his window is Roderigo, he reminds him that he told him not to come around his house anymore. However, both of these areas of tension are quickly eliminated because of Iago's art of persuasion and quick thinking.
In Act One, Scene One of the play Othello by William Shakespeare the playwright chooses to set the scene in a certain way in order to create an atmosphere of tension and confusion. He has Desdemona's father sleeping in his bed,presumably at night to add some danger and mystery, and disturbed by two nightime visitors. These visitors are Roderigo and Iago (respectively a gentleman in love with Brabantio's daughter Desdemona, and a soldier's "lieutenant" to Othello the famous military warrior.) They make Desdemona's leaving sound like a hysterical rebellion to rouse Brabantio's (and the audience's blood.) In emotive terms they emphasise Desdemona's "defiance" and add suspense and tension by describing the secretive nature of her marriage to Othello.