What is Roderigo's function in Othello?
Roderigo functions as a pawn for Iago. As a rejected suitor of Desdemona, he is easily manipulated by Iago in Iago's quest for vengence against Othello. Roderigo believes everything Iago tells him and does everything Iago asks of him. As a result, we feel sorry for Roderigo in the end because he is so easily mislead by Iago and because Iago, in whom Roderigo had placed so much trust, eventually kills Roderigo.
Roderigo seems to appear like Iago's inner-self and gives the auidence a look into the perception of self-concept and self-esteem of Iago's demorlizing character.
One has to recall that Shakespeare's Othello is an adaptation of Giraldi Cintho's " The Moor of Venice". Shakespeare divided the Ensign character ( Iago) into Iago and Roderigo. In Shakespeare's version Iago has no human qualities for the remorse that he causes from his evil actions. Whereas, Roderigo shows a more human side of Iago.