Expain the theme "loyalty & betrayal" in the play Othello with characters related to this theme, explanation, and quotes.

In Act I of Othello, Iago is disloyal
to Othello as he exposes his secret marriage to Desdemona by summoning Brabantio.
 Brabantio is disloyal to Othello because he had liked him up until he married his
daughter.  The Duke is the only one loyal to Othello, as he makes him General to Cyprus
and even lets Desdemona accompany him.  Desdemona is disloyal to her father, as she
deceives him by eloping.  Iago is disloyal to Roderigo, as he openly says "I am not what
I am" and just uses him for money.  Othello is loyal to all, although Iago complains
that he was passed over by the Moor to be his lieutenant.  Disloyalty to women and
loyalty to male reputation, to me, are the primary tragic mistakes in the
play.

In Acts II-IV, Iago ensnares two prime victims:
Cassio and Desdemona who only APPEAR to be disloyal to Othello.  Othello puts too much
faith in the possession of the handkerchief, and nearly everyone has their hands one it:
Emilia, Iago, Cassio, and--worst--Biancha, a prostitute.  When Othello sees this, he
effectively divorces Desdemona and swears a blood oath to Iago to commit double murder
against the adulterers.

In Act V, as the previous editor
said, Desdemona is loyal to Othello to a fault.  Her foil is Emilia, who is disloyal to
Iago, which, of course, makes her loyal to the memory of Desdemona.  Both are killed by
their husbands.  Loyal or disloyal to husbands, either way, women are doomed in this
play.

Shakespeare would have us believe, then, that his
society was riddled with sexism, misogyny, and double standards in marriage that state
men can talk openly and have affairs openly, but women can do
neither.