Lear's world falls apart because he trusts himself too much; he thinks he can manipulate events, tell who loves him, and stay king even after setting his throne aside. He is proud and full of power at the start of the play, but he crumbles into doubt and, eventually, madness.
The entire play follows Lear down from the throne and into exile; from there, he weathers a storm, despair, and madness.
Lear dies at the end of the play.
Edmund schemes, first to displace his brother, Edgar, and then to betray his father. He lies and manipulates. He has affairs with both Regan and Goneril.
When he is charged with treason in Act 5, he fights an anonymous challenger who is seeking to prove Edmund's guilt through trial by combat. This unknown knight turns out to be his brother, Edgar, who kills Edmund.
Edgar starts the play quite naïve, and he is quickly taken in by his brother's schemes. Once he's banished, he disguises himself as Poor Tom, a crazy beggar, to stay in the kingdom. He cares for his father, showing his loyalty.
Edgar guides his father through a suicide attempt, lying to him as Gloucester leaps from what he thinks are the cliffs of Dover.
Edgar rises in stature throughout the play, killing the treacherous Goneril's servant Oswald and his own traitorous brother, Edmund.
In the play's final lines, Edgar is made joint ruler of the kingdom.
Earl of Gloucester
Gloucester is an older nobleman within Lear's kingdom. He is quite loyal to Lear and at times stands in for him. Gloucester has two sons: Edgar, his older and legitimate son, and Edmund, who is illegitimate.
Gloucester is deceived by Edmund's betrayal of Edgar, and he banishes his elder son. Gloucester remains loyal to Lear throughout, and the Duke of Cornwall punishes him for this loyalty by gouging his eyes out. Gloucester wants to kill himself due to his despair, and he asks someone he thinks is a poor beggar to guide him to the cliffs of Dover.
Gloucester dies at the end of the play.
When Lear divides his kingdom in Act 1, Scene 1, Cordelia refuses to play her assigned role and declare how much she loves her father. As a result, he strips her of her dowry. Only the King of France is willing to marry her without a dowry, a fact that shapes her fate and Britain's.
She is absent through most of the first three acts, then returns to Britain late in the play, bringing French forces with her. In the final battle, the rebel forces capture her. Edmund arranges for her to be put to death, and she's hanged in Act 5. Because of her steadfast loyalty to her father, she is a saintly figure throughout King Lear.
Goneril is a true villain. She shows this by lying to her father about how much she loves him and by acting to erode Lear's authority and position. She's married to the Duke of Albany, but as she rebels against her father and seeks power, her relationship with her husband deteriorates until the two of them actively loathe one another.
She begins an affair with Edmund. When he's killed, she poisons her sister Regan and stabs herself.
Like Goneril, Regan is a true villain. At the beginning of the play, she makes public declarations of intense love for her father, but she follows this by finding ways to undermine his authority. She and Goneril turn their father out to wander in a storm.
Regan suggests that her husband, the Duke of Cornwall, blind Gloucester for his treachery. When a servant tries to prevent this, she picks up a sword and kills him.
Like Goneril, she begins an affair with Edmund and dies after he's killed, when Goneril poisons her.