How does Othello's character change in the play 'Othello'?

Othello shows the rise and fall of a black hero who starts as a great man, a hero, good husband, great storyteller, a favorite among his men, but then becomes irrational, jealous, petulant, paranoid, and ultimately violent toward himself and others. He murders his own wife after he is convinced that she has been cheating on him and realizing his mistake, takes his own life.

As to the importance of his color, this was only a point to those that were looking for something to hold against him when nothing else would suffice. Desdemona's father was not above playing the race card when he said that "Othello must have "enchanted" Desdemona with "foul charms" and magic spells. Otherwise, he insists, Desdemona never would never have run "to the sooty bosom" of Othello (1.2.2)