King Lear is presented as a victim of deceit. He is deceived by his own daughters Goneril and Regan, who really care very little about him but express their love in the most extravagant terms when they are competing for portions of their father's kingdom. But the shock and pain occasioned by his realization of his daughters' deceitfulness make Lear conscious of the fact that people have been deceiving him all his life.
They flattered me like a dog; and told me I had white hairs in my beard ere the
black ones were there. To say ‘ay’ and ‘no’ to every thing that
I said!—‘Ay’ and ‘no’ too was no good divinity. When the
rain came to wet me once, and the wind to make me chatter;
when the thunder would not peace at my bidding; there I
found 'em, there I smelt 'em out. Go to, they are not men o'
their words: they told me I was every thing; 'tis a lie, I am
As a prince and heir apparent to the throne, Lear would have been surrouinded by flatterers who agreed with everything he said and laughed heartily at his jokes. And then as king he would have been made to feel that he was admirable and infallible. He has come to think of himself as a very wise and charming person, but Goneril and Regan know he is just a selfish and gullible old man who thinks he can buy love. He was a victim of all the courtiers because he never had the opportunity to see the wicked side of humaniity. It was not until he lost all his lands, income, and military power that he began to see the truth. His Fool has known the truth about human nature all his life because he was probably the village idiot whom Lear adopted on a whim and used for his entertainment. As a halfwit and a pauper the Fool would have been exposed all kinds of verbal and physical abuse. Only Kent, Cordelia, Gloucester and the Fool remain loyal to him, but these characters are mainly necessary to serve as contrast, or foils, to the cunning and evil ones.
As Lear says in Act 3, Scene 2, "I am a man / More sinned against than sinning." He has been victimized by many people besides his two daughters. His tragic flaw is that he has been too trusting, too gullible. People have made a fool of him, which is why his Fool calls him a fool.