this was the best filler episode of all time.

the atla fillers were so good half the time i didn’t even realize they were fillers

I love Zuko’s reaction. Maybe because just then, it seems like he realized he could die, without EVER gaining his ‘Honor’ back. Remember, Zuko was obsessed with getting his honor back in the first season. And even then, he was driven in the sense that he could find a way to get his honor back. Defeat the Avatar? Join the Avatar. He was always convinced that he would succeed and get back his honor. 

This is him seeing the possibility that his sister Azula could kill him, and he may never achieve his goal. 

BUT MAYBE I’M READING THIS COMPLETELY THE WRONG WAY! Who knows?