Kent is angry at Oswald primarily due to Oswald’s disrespectful behavior towards King Lear and his own loyalty to Lear. In Act 1, Scene 4, when Kent encounters Oswald, who is Goneril’s steward, he perceives Oswald as arrogant and unworthy. Oswald shows contempt for Kent, which provokes Kent’s anger. His frustration is further amplified by the fact that Oswald is facilitating Goneril’s mistreatment of Lear, displaying a lack of honor and respect for the king.
Kent’s anger highlights his fierce loyalty and sense of justice. He sees himself as a protector of Lear’s dignity and can’t tolerate anyone undermining the king, especially someone who serves Lear’s own daughters. Consequently, Kent’s outrage leads him to confront Oswald, which escalates the conflict between the characters. This moment sets the tone for the ongoing struggle against the themes of betrayal and loyalty that permeate the play.