Jack pretends to have a brother named Ernest because it allows him to live a double life. By creating this fictitious brother, Jack can escape his responsibilities and obligations in the country and indulge in a more exciting and carefree lifestyle in the city as "Ernest". This deception also allows Jack to keep his true identity a secret from his ward, Cecily, and the other characters in the play. Ultimately, Jack's creation of Ernest leads to a series of comedic misunderstandings and complications that drive the plot of the play.
