How did Edmund disappoint Lucy? Was this behavior typical of his personality?

Edmund disappoints Lucy when he lies to Susan and Peter, refusing to corroborate Lucy's story about Narnia. In doing so, an interesting irony arises: Lucy, the more truthful of the two, is thought to be a liar, while Edmund, who is actually lying, is believed to be telling the truth. This behavior is typical of Edmund.

Edmund disappointed Lucy by telling Susan and Peter that he hadn't been to Narnia and that he was just playing around with lucy. This behviour is typical of Edmund as he loves to tease and make fun of Lucy. He also hates to admit that he was wrong and that is the main reasn he lied.