Shakespeare creates the character of Iago as the villain of the play. Iago is the driving force of the plot behind the scenes in Act 1 as he manipulates the other characters, particularly Roderigo, and formulates schemes throughout the first act. In the first scene of the play Iago is complaining about not having received the promotion to lieutenant that he felt he deserved. Therefore we immediately see that he is a negative character and Shakespeare portrays him as having a disagreeable persona. We also discover that Iago "hast had my (Roderigo's) purse", that Roderigo has given him free reign over his personal wealth and Iago has let Roderigo down as he has been hiding something from him. However, we have been placed in medias res and are unaware of what "this" is that Iago has been hiding. Thus begins the development of the idea that Iago is untrustworthy and a schemer.
Another piece of information that we learn is the social status that Iago claims to hold. He asserts that he is in favour of the "three great ones of the city". Moreover it too becomes clear that he is the right-hand man to Othello, having the especially personal position of being a standard-bearer. This leads you to believe that he is a member of a reasonably upper-class family, which is further emphasised by his use of complex sentences and high register and figurative language. Shakespeare demonstrates Iago's wide range of vocabulary by using words such as 'epithets' and 'knee-crooking knave' as well as the use of plosive syllables and words such as 'prattle without practice' and 'bombast'. This also shows that he is his an articulate character when he so wishes. .
A different component of Iago's character is the manipulative ways in which he tries to get what he desires. One way in which he manipulates Roderigo is by trying to legitimise his arguments and plans by presenting Othello in an uncomplimentary manner.