William Shakespeare used letters as a dramatic device to reveal the characters' loyalty and betrayal in his play King Lear. The purpose of the letter is to develop the plot and reveal the characters' attributes. Three letters help to develop the plot and reveal the characters of Edmund, Gloucester, Goneril and Albany.
The first letter that appeared on the stage is Edmund's false letter. The letter talked about Edgar's plan to kill to his father, Gloucester. Edmund made up this letter to plan against his brother Edgar. Edmund lied to Gloucester about the letter. This letter developed the subplot in King Lear and it shows us that Edmund betrayed his brother. Edmund planned to destroy the love of Gloucester for Edgar, so Edmund can get what he wants. This false letter revealed that Edmund wasn't loyal to his family and he betrayed his brother.
Another important letter that appeared on the stage is talking about French invasion. This letter was written to Gloucester. Gloucester decided to help Lear after he read the letter. Gloucester worried about Lear and this revealed Gloucester 's loyalty to the old king. Gloucester told his decision to Edmund after Gloucester finished the letter. Edmund decided to tell Cornwall about Gloucester 's action. Edmund told Cornwall that his father was traitor who wanted to help France. Edmund did this to receive more power and get the credit from Duke of Cornwall. The action of Edmund displayed that he would do anything to get higher rank. He even betrayed his father who is horribly punished. Edmund becomes the Earl of Gloucester. Edmund had no loyalty to his father. In Act III, the letter was in Albany's hand. Albany chose to fight the French army and that showed his loyalty to England.
The last letter on the stage talked about the plan of murder Albany. It was written by Goneril to Edmund. Goneril didn't love her husband and planned to kill him. Goneril wanted Edmund to be her husband. The letter proved that Goneril was going to betray her husband, Albany. This also means she would betray their marriage.
In King Lear, letters developed the story and displayed the characters' loyalty or betrayal. Edmund's false letter showed the betrayal between brothers. Edmund used the letter about French invasion to get higher rank by betray his father, Gloucester. Gloucester decided to help Lear once he knew of the invasion. Albany would fight for England even he knew the army trying to rescue Lear. Goneril sent a letter about the betrayal of Albany, her husband. The actions and reactions of the characters had showed their loyalty and betrayal when there is a letter in King Lear.