The Lion, the Witch, and the Wardrobe
How we cite our quotes:
And now we come to one of the nastiest things in this story. Up to that moment Edmund had been feeling sick, and sulky, and annoyed with Lucy for being right, but he hadn't made up his mind what to do. When Peter suddenly asked him the question he decided all at once to do the meanest and most spiteful thing he could think of. He decided to let Lucy down. (5.4)
Edmund's first betrayal is a small but unpleasant one – he lies about his trip to Narnia in order to make himself look superior in the eyes of Peter and Susan. This small cruelty will pave the way for his greater treachery later on.
"The reason there's no use looking," said Mr. Beaver, "is that we know already where he's gone!" Everyone stared in amazement. "Don't you understand?" said Mr. Beaver. "He's gone to her, to the White Witch. He has betrayed us all." (8.53)
Mr. Beaver isn't prejudiced by a family relationship to Edmund, and he's able to recognize right away that Edmund's sudden disappearance means trouble and danger.
"I didn't like to mention it before (he being your brother and all) but the moment I set eyes on that brother of yours I said to myself 'Treacherous.' He had the look of one who has been with the Witch and eaten her food. You can always tell them if you've lived long in Narnia, something about their eyes." (8.61)
Like most people in Narnia, Edmund wears his heart on his sleeve. OK, well, nobody falls in love here, but you know what we mean – he wears his thoughts on his face. Appearances are rarely deceptive in this world, and if Peter, Susan, and Lucy had known what to look for, they might also have realized what was happening to Edmund.