Chapter 31 has the letter from Monk Yuan-ti, and while everyone else is horrified to hear it, Aang shrugs it off like it's nothing:
"Several of our younger sisters, especially among the bearing, were most distressed to witness the Avatar's will. I counseled the elders to bring all back into harmonious accord, as while mercy and compassion are tender illusions, they yet cause the spirit to remain attached to things of this world, and must all be pruned away. Else as you know yourself, one will desire more of what can only pass away and be forgotten. And how, then, would we know the transcendent joy of teaching our pupils freedom, if those who bear them will not give them up..."
Chapter 56 touches on 'Quality Time with Daddy':
The princess had a satisfied smile on her face. "The records say Great-Grandmother loved this place."
Mai let her brows climb. "I've never heard much about Fire Lady Tejina."
"Oh, she was interesting.
" Azula stared at dancing flames. "She recorded just how close you can bring someone to lava before their hair starts burning off. Among other things."
...And maybe I don't want to hear much now.
"Where did you read that?"
"Oh, Father read it first. He told me the stories, every night. The executions, the interrogations... what?"
"These were..." Mai swallowed, somehow not surprised at all. "Bedtime stories?"
"They were mine." Azula looked stubborn. "Zuko had his time with Mother. Father spent time with me."
Chapter 89: Say Goodnight, Ozai:
Dark as blood, silk struck phosphorescent water-
Sokka's eyes widened, and he jerked his gaze away, wishing he could bury himself in Appa's fur. Wishing, for one desperate moment, he was as blind as Toph.
Dead hands in water. Empty eye sockets. Snapping teeth.
...I am never, ever telling Zuko.