Othello is a tragedy written by William Shakespeare, Poet and Playwright, in the 1600's. Iago is a major character pivotal to the story's outcome and development. He is the main antagonist of the play, but not pure evil; displaying multiple personality traits including villainous, jocular, and deceptive qualities amalgamating into an identity generally perceived to be wicked. His basic aim is to destroy the lives of Othello and to a certain extent, Cassio (any other lives that are also affected are a bonus). While that is his objective, it is not his motive, - not to suggest that he has any. Iago is a "motiveless malignancy", in the sense that, all his actions are caused by personal desires or reactions to circumstances. He doesn't have any motives, as he has nothing qualitative to gain from his actions. Love or emotion, true or not, serves an important part in his plan and Iago, himself is influenced by it.
He goes beyond the minimum requirements for certain objectives, i.e. to replace Cassio as Lieutenant, raising doubts as to whether he enjoys deceiving others, or is captured in his own web-trap of lies. Iago is a complicated man who commits crimes not out of motive, but for other objectives stemming from his personality, and surrounding circumstances.
Iago does not proactively perpetrate his plan; rather it is in retaliation for injustices that he believed were inflicted on him. He hates Othello for promoting Cassio, an accountant with no war experience whatsoever, to Lieutenancy, over himself. Iago decides to quietly respond, by destroying Othello's life. In the play, Iago only stated that he hated "The Moor", but never why he did so. It makes one wonder, why he hates his boss, even though Othello holds Iago in the highest esteem. "My friend, thy husband,