[Her questioning of this strikes him, making him feel regretful about the decision and thankful for her insight. But he didn't know how to tiptoe around the issue, especially telling her that she had already approved of it.]

Honestly, Katara, no. It's... the last thing I wanted, especially at that time, after everything I went through to stop Ozai without... doing the same to him. But I think that at that time, you understood. He wouldn't want to live with himself if he became like that. And... as much as I hate to think about it... I remember everything about Roku and Sozin, and how much could have been avoided if Sozin was... you know, taken care of. I don't think I even thought that much when he asked me. With all of the celebrations going on, I didn't think that I'd... ever have to act on the promise.