The Lion, the Witch, and the Wardrobe
How we cite our quotes:
You mustn't think that even now Edmund was quite so bad that he actually wanted his brother and sisters to be turned into stone. He did want Turkish Delight and to be a Prince (and later a King) and to pay Peter out for calling him a beast. As for what the Witch would do with the others, he didn't want her to be particularly nice to them – certainly not to put them on the same level as himself – but he managed to believe, or to pretend he believed, that she wouldn't do anything very bad to them (9.3)
The narrator is careful to explain that Edmund isn't a completely evil being. He's just allowed some of his more negative qualities, like selfishness, greed, and constantly feeling ill-treated by his brother and sisters, to affect his actions disproportionately. He lies to himself about the real consequences of his actions.
And Edmund stood in the shadow of the arch, afraid to go on and afraid to go back, with his knees knocking together. He stood there so long that his teeth would have been chattering with cold even if they had not been chattering with fear. How long this really lasted I don't know, but it seemed to Edmund to last for hours. (9.9)
It takes a great and awful effort for Edmund to take the last steps through the Witch's courtyard and deliver his siblings into her hands. Unfortunately, he goes through with it.
Edmund meanwhile had been having a most disappointing time. When the Dwarf had gone to get the sledge ready he expected that the Witch would start being nice to him, as she had been at their last meeting. But she said nothing at all. (11.1)
We really shouldn't be surprised that the Witch betrays her promises to Edmund almost as quickly as he betrays his family.