Brutus is different from Cassius for he is always calm, straight forward, and noble, but he is also very gullible.
Brutus came from noble birth, had a fatal flaw, suffered a great tragedy. Brutus also, makes statements on people without any exceptions. Iago is determined to destroy Othello and his loved ones. They both consider Caesar to be a danger, and perceive his aspiration to be the best and run totally finished Rome and Italy.
When plotting against Caesar at Brutus's home, Act II, scene two linesCassius wants to also kill Antony and anyone else who may cause trouble for them after Caesar's murder. Then there is Cassius who is a perceptive person and very manipulative. While some characters are not featured heavily in the main plot, they serve as a means by which the author can illuminate aspects of the main characters, which are important to the plot development and overall depth of the story.