Roderigo is paying Iago money to give him information about Desdemona, who he wishes to marry.
Brabantio has already rejected him as a suitor but this does not stop his pursuit of her.
Iago
Roderigo is often melancholic and full of self-pity, lamenting his own situation.
However, there is no room for his development and so he is killed.
Iago has played him for most of the play.
It is only when he faces mortality that he realises Iago’s true nature.
Love and tragedy
Roderigo believes that love can be bought and paid for, but he comes to understand that it cannot be.
His function in the tragic plot is to be duped by Iago, and this contributes to his death.
Brabantio
A ‘reverend signor’ Brabantio is an elderly man whose daughter is Desdemona.
Brabantio
Brabantio is a respected figure in Venetian society. He is distraught when he learns that Desdemona has married a Moor.
He views him as having stolen her (so she is his property) and that he has achieved this through witchcraft.
Racism
Brabantio offers much of the racist abuse in the play.
He orders Othello to appear before the Duke of Venice to justify himself in a kind of trial.
He is very forthright and opinionated.
Mirrored emotions
Brabantio's slide into despair is matched by Othello’s happiness at being married to Desdemona.
We learn of his death later in the play.
Love
Brabantio is an important character in terms of restricting love and not permitting marriage.
Tragedy
The play implies that is dissatisfaction with his daughter’s choice of husband throws him into such despair that he dies.
Interestingly, retrospectively the audience may see that his concerns over Desdemona and Othello’s pairing were right: he foresaw that tragedy and chaos might result from their union.