CORNWALL: Edmund, I hear that you have shown your father
A childlike office.
EDMUND: It was my dury, sir.

– William Shakespeare

King Lear, Act 2, Scene 1. Gloucester and others are completely taken in by Edmund’s vicious lies about Edgar. The Duke of Cornwall says that he has been told Edmund acted like a true son to his father Gloucester. Basking in his new popularity, Edmund replies that it was his duty, suggesting that it is a child’s duty to protect his father. The reality is that Edmund is not a good son, but an evil villain scheming to usurp Gloucester’s title and possessions from Edgar.