Chronicles of Narnia 3
Edmand betrayed his family because of three reasons. One, he did not like being treated so cruelly by his siblings and the Witch had been so kind to him. (Then again his siblings treating him so cruelly were in result of his own spite and foolishness.) Two, as the book mentioned, once one has a taste of enchanted food, you will crave more; he simply wanted more Turkish Delight! Three, he was full of arrogance, conceit and revenge of being king and having his siblings be his servants. Edmand truly is a devious boy. When suffering the hardships of the cold, he pressed on with the idea of ruling his siblings and the wood and becoming a feared tyrant! As soon as Edmand had convinced himself that the Witch was good and had told her the information, her coldness told him that he had been used.
Instead of being tenderhearted as before, she was just as spiteful as him, and grew worse. She called him ‘the human creature’ instead of ‘Son of Adam’ or ‘Prince.’ Three main events show the Witch is evil. One, she turned the creatures to stone who had been visited by Father Christmas out of pure anger of defeat by Aslan. Two, she smote Edmand and forced him to suffer hardship. (in the sledge of bitter cold with no real food, and being driven like an animal on a rope when the sledge could no longer be driven) Three, she threatened the lives of Edmand and the dwarf for just saying Aslan’s name.