Shakespeare makes adjustments to Cinthio's version:
-Adds Iago's ambiguity to portray himself as more evil than Cinthio's Ensign and gives him more time through his soliloquies
-Shakespeare adds Brabantio add to Othello's insecurities as he opposes his marriage to his daughter through his ethnicity - a potential reason why he succumbs to Iago's manipulations
-Roderigo is added to add more depth to Iago's character, another character to manipulate, giving the reader a greater impression of Iago's web of authority