I replay Book 2 incest route every year. Zuko is my favorite character of all time and Azula is ... well - Azula.
But the thing that catches me off-guard each and every time is not how abusive the sex is, nor how loving the relationship is if you abstract away Azula's obvious trauma and her lashing out at everyone in compensation. No, that's exactly what I'm here for. What catches me off-guard each and every time, is the humor.
You have to meet some shady guy in the alleyway. You see two mustle bound oafs chasing a hobo, and you decide to FUCKING DECK the hobo. The idiots ask you "Why tho?", "Eh, just because", "Respect bro!".
Or when azula wants to get you angry so that you can fire bend, and she asks:
"What makes you angry, brother?"
"Small tits!"
I nose fart every time.